JP2005191711A - Imaging system and method therefor, regeneration system and program thereof, and imaging regeneration system and program thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging system or the like, capable of handling output signals obtained by a plurality of gray level conversion characteristics, using a smaller memory capacity and at a high speed. <P>SOLUTION: In the imaging system or the like, when a video signal obtained by imaging is processed, on the basis of the plurality of gray level conversion characteristics and recorded in a memory card or the like; a video signal (A) by a reference gray level conversion curve is separated into a luminance signal Y<SB>1</SB>(B), a color-difference signal Cb<SB>1</SB>(C), and a color-difference signal Cr<SB>1</SB>(D). Similarly, a luminance signal Y<SB>2</SB>(F) is separated from a video signal (E) by a gray level conversion curve which is out of the reference. Furthermore, a difference signal Y<SB>1</SB>-Y<SB>2</SB>(I) is calculated, and after irreversible compression of the luminance signal Y<SB>1</SB>and the color-difference signals Cb<SB>1</SB>, Cr<SB>1</SB>are performed, reversible compression of the difference signal Y<SB>1</SB>-Y<SB>2</SB>is performed, and after that they are recorded respectively. When the video signal by the gray level conversion curve which is out of reference is regenerated, the luminance signal Y<SB>2</SB>is restored from the difference signal Y<SB>1</SB>-Y<SB>2</SB>, and is used along with the color difference signals Cb<SB>1</SB>, Cr<SB>1</SB>. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an imaging system, a reproduction system, an imaging reproduction system, an imaging reproduction program, an imaging method, and a reproduction program for performing at least one of imaging and reproduction on a video signal corresponding to one or more gradation conversion characteristics. About.

  Digital still cameras and video cameras that are currently available on the market, in the input system and processing system rather than the final output signal gradation width (usually 8 bits), in order to prevent image quality degradation due to digit signal processing loss. In general, the signal has a wide gradation width (about 10 to 12 bits).

  In such a configuration, when a signal processed in the processing system is sent to the output system, it is necessary to perform gradation conversion so as to match the gradation width of the output system. This gradation conversion has been conventionally performed based on a fixed gradation conversion characteristic adapted to a standard shooting scene.

  On the other hand, a technique has been proposed in which a plurality of images with different exposure amounts are combined to generate a wide dynamic range signal with a wider gradation width.

  Even in such a configuration, as described above, when the obtained wide dynamic range signal is sent to the output system, it is necessary to perform gradation conversion so as to match the gradation width of the output system.

  For example, Japanese Patent Laid-Open No. 2001-238128 describes a technique for generating image data with a wide dynamic range as described above. The gradation conversion in this publication is performed by estimating the shooting situation, and thereby the main subject. It is an adaptive conversion that places emphasis on.

  In addition, there is a technique for storing raw raw data from the image sensor and separately performing post-processing in order to perform a plurality of gradation conversions different from the standard gradation conversion characteristics.

Further, for example, in Japanese Patent Laid-Open No. 10-285541, the entire process of signal processing is stored separately, and the processed signal is reverse-processed to return to a signal at an appropriate stage, and then another process is performed. The technology to make is described.
JP 2001-238128 A Japanese Patent Laid-Open No. 10-285541

  Since the gradation conversion based on the fixed gradation conversion characteristics as described above is adapted to a standard shooting scene, an appropriate video signal may not always be obtained in a non-standard shooting scene such as backlight. Can not.

  Further, in the technique described in Japanese Patent Laid-Open No. 2001-238128, the gradation conversion based on the estimation result of the shooting situation may not conform to the photographer's intention. For example, there are cases where many gradations are assigned to the main subject by automatic processing, but the photographer wants to assign gradations to the background or the like. Thus, the technique described in the publication does not always provide a preferable output signal for the photographer.

  On the other hand, when storing unprocessed raw data, there are problems such as an increase in the amount of memory for storage and an increase in cost, as well as troublesome signal processing.

  Furthermore, in the technique described in Japanese Patent Laid-Open No. 10-285541, a part of the gradation information is lost even if the gradation width of the output signal (8 bits) is inversely converted to the gradation width at the time of input (10 to 12 bits). Therefore, when tone conversion with different characteristics is performed on the inversely converted signal, there is a problem in image quality such as discontinuity in tone.

  The present invention has been made in view of the above circumstances, and an imaging system, a playback system, an imaging playback system, an imaging playback program, an imaging method, which can handle output signals based on a plurality of gradation conversion characteristics at high speed in a memory-saving manner, The purpose is to provide a playback program.

  In order to achieve the above object, an imaging system according to a first aspect of the present invention provides an output system based on a gradation conversion curve serving as a predetermined reference for a video signal having a gradation width of Mbit (M is a natural number) from the imaging system. Nbit (N is a natural number, and a number satisfying M ≧ N) is converted to a video signal having a gradation width and, if necessary, a gradation conversion curve outside the reference different from the reference gradation conversion curve A gradation converting means for converting to an image signal having an Nbit gradation width of an output system based on the above, a separating means for separating the video signal converted by the gradation converting means into a luminance signal and a color difference signal, and the reference Compression means for compressing a luminance signal and a color difference signal obtained based on the gradation conversion curve to be and a luminance related signal related to the luminance signal obtained based on the non-reference gradation conversion curve, if necessary. Equipped A.

  The image pickup system according to the second aspect of the invention is a separation means for separating a video signal having a gradation width of Mbit (M is a natural number) from the image pickup system into a luminance signal and a color difference signal, and the Mbit separated by the separation means. Is converted to a luminance signal having a gradation width of N bits (N is a natural number and satisfies M ≧ N) on the basis of a gradation conversion curve serving as a predetermined reference, and as necessary. A gradation converting means for converting to a luminance signal having the Nbit gradation width based on a gradation conversion curve that is different from the reference gradation conversion curve, and an Mbit level separated by the separating means. A color difference signal having a tone width is converted into a color difference signal having a tone width of N bits, and the luminance signal separated by the separating means and the reference tone converting curve by the tone converting means. Color difference correction means for correcting using the luminance signal converted on the basis of the luminance signal obtained based on the reference gradation conversion curve and the corrected color difference signal, and if necessary, Compression means for compressing the luminance related signal related to the luminance signal obtained based on the tone conversion curve.

  Furthermore, in the imaging system according to a third aspect of the present invention, in the imaging system according to the first or second aspect, the luminance-related signal is a luminance signal itself obtained based on a gradation conversion curve that is out of the reference.

  An imaging system according to a fourth invention is the imaging system according to the first or second invention, wherein the luminance-related signal includes a luminance signal obtained based on the reference gradation conversion curve, and a floor other than the reference. This is a difference signal that is a difference from the luminance signal obtained based on the tone conversion curve, and further includes a luminance difference calculation means for calculating the difference signal as necessary.

  An imaging system according to a fifth invention is the imaging system according to any of the first to fourth inventions, wherein kbit (k is a natural number and M ≧ k) obtained by imaging the same subject under different exposure conditions. The image processing apparatus further includes combining means for generating the video signal having the Mbit gradation width by combining at least two images composed of the video signals having the gradation width of the number to be satisfied.

  An imaging system according to a sixth invention is the imaging system according to any one of the first to fifth inventions, wherein the gradation converting means has recording means for recording a reference gradation conversion curve. is there.

  An imaging system according to a seventh aspect is the imaging system according to the sixth aspect, wherein the gradation converting means calculates the non-reference gradation conversion curve based on the reference gradation conversion curve. The apparatus further includes a conversion curve calculation unit.

  An imaging system according to an eighth invention is the imaging system according to the seventh invention, further comprising estimation means for estimating a shooting situation, wherein the gradation conversion curve calculation means is adapted to the shooting situation estimated by the estimation means. Accordingly, the calculated gradation conversion curve outside the reference is made different.

  An imaging system according to a ninth invention is the imaging system according to the seventh invention, wherein the gradation converting means calculates a feature quantity with respect to the video signal or the luminance signal, and based on the feature quantity. A histogram generation means for generating a histogram, a gradation conversion curve calculation means for calculating a gradation conversion curve based on the histogram, and a level calculated by the gradation conversion curve calculation means based on the reference gradation conversion curve. Limiting means for calculating a non-standard gradation conversion curve by imposing a restriction on the tone conversion curve.

  An imaging system according to a tenth aspect of the invention is the imaging system according to any of the first to fifth aspects of the invention, obtained based on the luminance signal obtained based on the reference gradation conversion curve and the gradation conversion curve outside the reference. Header information generating means for generating header information so as to include the identification information generated by generating identification information for identifying the luminance related signal related to the luminance signal, the compressed luminance signal and the compressed Output means for outputting at least one of the luminance related signals, the compressed color difference signal, and the header information as one file.

  An image pickup system according to an eleventh aspect of the invention is the image pickup system according to any of the first to fifth aspects, further comprising thumbnail generation means for generating a thumbnail image of a predetermined size based on the video signal subjected to gradation conversion. is there.

  An image pickup system according to a twelfth aspect of the present invention is the image pickup system according to the eleventh aspect of the present invention, wherein the luminance signal obtained based on the reference gradation conversion curve and the luminance signal obtained based on the non-reference gradation conversion curve are used. Header information generating means for generating header information so as to include the identification information and the thumbnail image generated by generating identification information for identifying the luminance related signal according to the above, the compressed luminance signal and the above The apparatus further comprises output means for outputting at least one of the compressed luminance-related signals, the compressed color difference signal, and the header information as one file.

  An image pickup system according to a thirteenth aspect of the present invention is the image pickup system according to the eleventh aspect of the present invention, further comprising display means for displaying the thumbnail image.

  An imaging system according to a fourteenth invention is the imaging system according to the thirteenth invention, further comprising thumbnail selection means for selecting the thumbnail image displayed on the display means.

  An imaging system according to a fifteenth aspect is the imaging system according to the fourteenth aspect, wherein at least one of a compressed luminance signal and a compressed luminance related signal related to a thumbnail image selected by the thumbnail selection means, and the reference Output means for outputting the compressed color difference signal corresponding to the tone conversion curve as one file.

  An imaging system according to a sixteenth aspect is the imaging system according to the fourteenth aspect, wherein a luminance signal and / or a luminance-related signal other than the luminance signal and / or the luminance-related signal related to the thumbnail image selected by the thumbnail selection means. Is further provided with an erasing means for erasing.

  An image pickup system according to a seventeenth aspect is the image pickup system according to the sixteenth aspect, wherein the erasing unit further deletes a thumbnail image other than the thumbnail image selected by the thumbnail selection unit. is there.

  An imaging system according to an eighteenth aspect of the invention is the imaging system according to the tenth or twelfth aspect of the invention, wherein luminance related information related to a luminance signal obtained based on the gradation conversion curve outside the reference is added to the header information. The apparatus further includes output control means for controlling the output means so as to output.

  A reproduction system according to a nineteenth aspect of the present invention includes a luminance signal obtained on the basis of a reference gradation conversion characteristic and compressed, a compressed color difference signal, and header information. A reproduction system that decompresses and outputs a compressed signal portion of a signal that further includes a compressed luminance-related signal related to a luminance signal obtained based on a gradation conversion curve that is different from the gradation conversion curve and different from the gradation conversion curve. A luminance signal selection means for selecting at least one of the compressed luminance signal and the compressed luminance-related signal based on the header information, the luminance signal selected by the luminance signal selection means, and / or Alternatively, the expansion means for expanding the luminance related signal and the color difference signal, and the video signal based on the luminance signal and / or the luminance related signal and the color difference signal expanded by the expansion means. A synthesizing means for synthesizing, in which comprises a.

  A reproduction system according to a twentieth aspect of the present invention is the reproduction system according to the nineteenth aspect of the invention, wherein the luminance signal selection means includes priority means for preferentially selecting a compressed luminance signal corresponding to a reference gradation conversion characteristic. It is configured to have.

  A playback system according to a twenty-first invention is the playback system according to the nineteenth invention, wherein the header information includes a thumbnail image, and the luminance signal selecting means includes a thumbnail image included in the header information. Reading means, display means for displaying the thumbnail image read by the reading means, thumbnail selecting means for selecting the thumbnail image displayed on the display means, and the thumbnail selecting means Priority means for preferentially selecting a compressed luminance signal and / or luminance related signal corresponding to a thumbnail image.

  A reproduction system according to a twenty-second invention is the reproduction system according to the twenty-first invention, wherein the luminance signal selecting means has a luminance other than a luminance signal and / or a luminance related signal related to the thumbnail image selected by the thumbnail selecting means. It further comprises an erasing means for erasing the signal and / or the luminance related signal.

  A playback system according to a twenty-third aspect is the playback system according to the twenty-second aspect, wherein the erasing means further deletes a thumbnail image other than the thumbnail image selected by the thumbnail selection means. is there.

  The reproduction system according to a twenty-fourth aspect of the invention is the reproduction system according to the nineteenth aspect of the invention, wherein the synthesizing means selects the luminance-related signal corresponding to the gradation conversion characteristic outside the reference by the luminance signal selection means. The apparatus has color difference correction means for correcting the color difference signal expanded by the expansion means.

  A reproduction system according to a twenty-fifth aspect of the present invention is the reproduction system according to the nineteenth aspect of the present invention, based on the luminance signal obtained based on the gradation conversion curve based on which the luminance related signal is the reference and the gradation conversion curve other than the reference. A difference signal that is a difference from the obtained luminance signal, and the synthesis unit, when the luminance related signal is selected by the luminance signal selection unit, to the luminance related signal expanded by the expansion unit, Luminance calculation means for calculating a luminance signal obtained based on the non-standard gradation conversion curve by adding the luminance signals obtained based on the reference gradation conversion curve expanded by the expansion means. It is configured to have.

  An image pickup method according to a twenty-sixth aspect of the present invention relates to a video signal having an Mbit (M is a natural number) gradation width from an image pickup system based on a gradation conversion curve serving as a predetermined reference, and Nbit (N is a natural number) of an output system. , A number satisfying M ≧ N) and, if necessary, the Nbit level of the output system based on a non-standard gradation conversion curve different from the standard gradation conversion curve. A gradation conversion procedure for converting to a video signal having an adjustment width, a separation procedure for separating the video signal converted by the gradation conversion procedure into a luminance signal and a color difference signal, and a reference gradation conversion curve. A compression procedure for compressing the luminance signal and the color difference signal obtained and, if necessary, a luminance related signal related to the luminance signal obtained based on the non-standard gradation conversion curve.

  An image pickup method according to a twenty-seventh aspect of the invention is a separation procedure for separating a video signal having a gradation width of Mbit (M is a natural number) from the image pickup system into a luminance signal and a color difference signal, and the Mbit levels separated by the separation procedure. A luminance signal having an adjustment width is converted to a luminance signal having a gradation width of N bits (N is a natural number and satisfies a number M ≧ N) based on a gradation conversion curve serving as a predetermined reference, and the above-described is performed as necessary. A gradation conversion procedure for converting to a luminance signal having the gradation width of Nbit based on a gradation conversion curve other than the reference gradation conversion curve that is different from the reference gradation conversion curve, and a gradation width of Mbit separated by the separation procedure described above The chrominance signal having the Nbit gradation width is converted into the chrominance signal having the Nbit gradation width and the luminance signal separated by the separation procedure and the reference gradation conversion curve by the gradation conversion procedure. Color difference correction procedure for correction using the converted luminance signal, the luminance signal obtained based on the reference gradation conversion curve, the corrected color difference signal, and, if necessary, gradation conversion outside the reference A compression procedure for compressing a luminance related signal related to the luminance signal obtained based on the curve.

  A reproduction program according to a twenty-eighth aspect of the invention includes a compressed luminance signal, a compressed color difference signal, and header information obtained based on a reference gradation conversion characteristic, and the reference gradation conversion curve as necessary. A reproduction program for decompressing and outputting a compressed signal portion of a signal that further includes a compressed luminance related signal related to a luminance signal obtained based on a gradation conversion curve outside the standard different from The computer selects a luminance signal selection procedure for selecting at least one of the compressed luminance signal and the compressed luminance related signal based on the header information, the luminance signal selected by the luminance signal selection procedure, and / or Alternatively, an expansion procedure for expanding the luminance related signal and the color difference signal, a luminance signal expanded by the expansion procedure and / or a luminance related signal and the color difference signal, and Is a program for executing the synthesis procedure, to synthesize the video signal on the basis of.

  A playback program according to a twenty-ninth invention is the playback program according to the twenty-eighth invention, wherein the header information includes a thumbnail image, and the luminance signal selection procedure includes a thumbnail image included in the header information. Read procedure, display procedure for displaying the thumbnail image read by the read procedure, thumbnail selection procedure for selecting the thumbnail image displayed by the display procedure, and the thumbnail image selected by the thumbnail selection procedure A priority procedure that preferentially selects a corresponding compressed luminance signal and / or luminance related signal.

  A reproduction program according to a thirtieth aspect of the invention is the reproduction program according to the twenty-eighth aspect of the invention, wherein the synthesis procedure is performed when a luminance related signal corresponding to a gradation conversion characteristic other than the reference is selected by the luminance signal selection procedure. This is a procedure including a color difference correction procedure for correcting the color difference signal expanded by the expansion procedure.

  According to a thirty-first aspect of the present invention, an image reproduction system having an Mbit (M is a natural number) gradation width from an image pickup system outputs Nbit (N is a natural number) of an output system based on a gradation conversion curve serving as a predetermined reference. Nbit of the output system based on a non-standard gradation conversion curve different from the reference gradation conversion curve as necessary. Based on gradation conversion means for converting to a video signal having a gradation width, separation means for separating the video signal converted by the gradation conversion means into a luminance signal and a color difference signal, and the reference gradation conversion curve Compression means for compressing the obtained luminance signal and color difference signal and, if necessary, a luminance-related signal related to the luminance signal obtained based on the non-standard gradation conversion curve, and the reference gradation conversion curve; Gain based Header information is generated so as to include the identification information generated by generating the identification information for identifying the luminance signal and the luminance-related signal related to the luminance signal obtained based on the non-standard gradation conversion curve An imaging system comprising: a header information generating means; a luminance signal selecting means for selecting at least one of the compressed luminance signal and the compressed luminance related signal based on the header information; and the luminance An expansion unit that expands the luminance signal and / or luminance-related signal selected by the signal selection unit and the color difference signal, and an image based on the luminance signal and / or the luminance-related signal and the color difference signal expanded by the expansion unit And a reproducing system including a synthesizing unit for synthesizing signals.

  An image reproduction system according to a thirty-second aspect of the present invention is a separation means for separating a video signal having a gradation width of Mbit (M is a natural number) from the imaging system into a luminance signal and a color difference signal, and the Mbit of the Mbit separated by the separation means A luminance signal having a gradation width is converted into a luminance signal having a gradation width of N bits (N is a natural number and satisfies M ≧ N) based on a gradation conversion curve serving as a predetermined reference, and if necessary. Tone conversion means for converting to a luminance signal having the Nbit gradation width based on a gradation conversion curve outside the reference different from the reference gradation conversion curve, and the Mbit gradation width separated by the separation means Is converted into a color difference signal having the N-bit gradation width and the luminance signal separated by the separation means and the reference gradation conversion curve by the gradation conversion means. Color difference correction means for correcting using the luminance signal converted on the basis of the luminance signal obtained based on the reference gradation conversion curve and the corrected color difference signal, and if necessary, Compression means for compressing the luminance related signal related to the luminance signal obtained based on the tone conversion curve, the luminance signal obtained based on the reference gradation conversion curve, and the gradation conversion curve other than the reference. An imaging system comprising: header information generating means for generating header information so as to include the identification information generated by generating identification information for identifying the luminance-related signal related to the luminance signal, and the header Luminance signal selection means for selecting at least one of the compressed luminance signal and the compressed luminance related signal based on the information, and the luminance signal selected by the luminance signal selection means And / or expansion means for expanding the luminance related signal and the color difference signal, and combining means for combining the luminance signal expanded by the expansion means and / or the video signal based on the luminance related signal and the color difference signal. And a playback system provided.

  According to a thirty-third aspect of the present invention, there is provided a program for reproducing an image signal having an Mbit (M is a natural number) gradation width from an imaging system based on a gradation conversion curve serving as a predetermined reference. An output system based on a non-standard gradation conversion curve that is different from the reference gradation conversion curve, if necessary, and converted to a video signal having a gradation width of a natural number satisfying M ≧ N) Gradation conversion procedure for converting to a video signal having an N-bit gradation width, a separation procedure for separating the video signal converted by the gradation conversion procedure into a luminance signal and a color difference signal, and a reference gradation conversion curve A compression procedure for compressing a luminance signal and a color difference signal obtained based on the luminance-related signal related to the luminance signal obtained based on the non-standard gradation conversion curve, if necessary, and the reference gradation conversion music A header including the identification information generated by generating identification information for identifying a luminance signal obtained based on the luminance signal and a luminance related signal related to the luminance signal obtained based on the non-standard gradation conversion curve A header information generation procedure for generating information, a luminance signal selection procedure for selecting at least one of the compressed luminance signal and the compressed luminance related signal based on the header information, and the luminance signal selection procedure. An expansion procedure for expanding the luminance signal and / or the luminance related signal and the color difference signal, and a combining procedure for combining the video signal based on the luminance signal and / or the luminance related signal and the color difference signal expanded by the expansion procedure, Is a program for executing

  According to a thirty-fourth aspect of the present invention, an image reproduction program is separated by a computer by a separation procedure for separating a video signal having Mbit (M is a natural number) gradation width from an imaging system into a luminance signal and a color difference signal, and the separation procedure described above. A luminance signal having an Mbit gradation width is converted into a luminance signal having a gradation width of Nbit (N is a natural number and a number satisfying M ≧ N) based on a gradation conversion curve serving as a predetermined reference and necessary. Accordingly, a gradation conversion procedure for converting to a luminance signal having the gradation width of Nbit based on a gradation conversion curve other than the reference gradation conversion curve different from the reference gradation conversion curve, and the Mbit levels separated by the separation procedure. A chrominance signal having a tone width is converted into a chrominance signal having a gradation width of N bits, the luminance signal separated by the separation procedure, and the reference by the gradation conversion procedure. The color difference correction procedure for correcting using the luminance signal converted based on the gradation conversion curve, the luminance signal obtained based on the reference gradation conversion curve, and the corrected color difference signal and the above as necessary. A compression procedure for compressing a luminance-related signal related to a luminance signal obtained based on a non-standard gradation conversion curve, a luminance signal obtained based on the reference gradation conversion curve, and the non-standard gradation conversion curve Header information generation procedure for generating header information so as to include the identification information generated by generating the identification information for identifying the luminance related signal related to the luminance signal obtained based on the above, and the compression based on the header information Luminance signal selection procedure for selecting at least one of the generated luminance signal and the compressed luminance related signal, the luminance signal selected by the luminance signal selection procedure and / or the luminance A program for executing a decompression procedure for decompressing a continuous signal and the color difference signal, and a synthesis procedure for synthesizing a video signal based on the luminance signal and / or the luminance related signal and the color difference signal decompressed by the decompression procedure. is there.

  According to the imaging system, the playback system, the imaging playback system, the imaging playback program, the imaging method, and the playback program of the present invention, it is possible to generate an output signal with a plurality of gradation conversion characteristics at high speed with less memory.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIGS. 1 to 5 show Embodiment 1 of the present invention. FIG. 1 is a block diagram showing the configuration of an imaging system, FIG. 2 is a diagram showing a plurality of gradation conversion curves, and FIG. FIG. 4 is a diagram illustrating a procedure for generating an output file based on image data generated by a tone conversion curve, FIG. 4 is a diagram illustrating a configuration example of an external I / F unit, and FIG. 5 illustrates processing performed by an imaging program in a computer. It is a flowchart.

  As shown in FIG. 1, the imaging system includes a lens system 1 for forming a subject image, and a diaphragm that is disposed in the lens system 1 and defines a light beam passage range in the lens system 1. 2, a low-pass filter 3 for removing unnecessary high-frequency components from the imaging light flux by the lens system 1, and an optical subject image formed through the low-pass filter 3 by photoelectric conversion to be electrically An image signal is output, for example, a CCD 4 that is an image pickup device such as a single-plate CCD having a primary color filter disposed on the front surface, and an analog image signal output from the CCD 4 is converted into a digital signal. The D converter 5 and one of the digital image data output from the A / D converter 5 in the pre-imaging mode or two digital image data in the main shooting are temporarily stored. A first image buffer 6 to be stored, and a second image buffer to temporarily store the other one of the two digital image data output from the A / D converter 5 at the time of main photographing. 7, a photometric evaluation unit 8 that performs photometric evaluation on the subject based on the image data stored in the first image buffer 6 and controls the diaphragm 2 and the CCD 4 based on the evaluation result, and the first image buffer 6 is included in the lens system 1 under the control of the in-focus detection unit 9 that detects AF point 10 based on the detection result and drives an AF motor 10 to be described later based on the detection result. AF motor 10 for driving the focus lens, etc., a single-plate image signal stored in the first image buffer 6 and a single-plate state stored in the second image buffer 7 An interpolating unit 11 that sequentially reads image signals and performs known interpolation processing, white balance processing, enhancement processing, and the like, and generates a three-plate video signal, and a short time of the three-plate state transferred from the interpolating unit 11 A synthesizing unit 12 as a synthesizing unit that generates one wide dynamic range image by synthesizing the exposure image and the long-time exposure image, and an operation for temporarily storing the wide dynamic range image generated by the synthesizing unit 12 The shooting situation is estimated based on the buffer 13, the reference curve ROM 14 serving as a recording means for storing a reference gradation conversion curve, and shooting information such as photometric information and in-focus information transferred from the control unit 25 described later. The shooting situation estimation unit 15 serving as estimation means, the reference gradation conversion curve read from the reference curve ROM 14, and the shooting situation estimation unit 15 A conversion curve calculation unit 16 serving as a gradation conversion curve calculation unit that calculates a gradation conversion curve based on the estimated shooting situation, and a video signal having a wide dynamic range is read from the work buffer 13 and the conversion curve calculation unit is read out. The tone conversion unit 17 serving as a tone conversion unit for converting into a video signal having a tone width of the output system (for example, an 8-bit tone width) based on the tone conversion curve calculated by 16, and the image from the tone conversion unit 17 A Y / C separation unit 18 as separation means for separating a signal into a luminance signal and a color difference signal, and a luminance signal and a color difference signal relating to a reference gradation conversion curve output from the Y / C separation unit 18 and out of the reference An output buffer 19 that temporarily stores the luminance signal related to the tone conversion curve of the image, and the luminance signal related to the reference tone conversion curve stored in the output buffer 19 and the tone conversion curve outside the reference A luminance difference calculation unit 20 serving as a luminance difference calculation unit that calculates a difference between the luminance signal and the luminance signal and a color difference signal relating to a gradation conversion curve serving as a reference from the output buffer 19, and the luminance difference A compression unit 21 as compression means for reversibly compressing the difference signal from the calculation unit 20 and a thumbnail creation unit 23 as thumbnail generation means for generating a thumbnail image for each gradation conversion curve based on the video signal from the gradation conversion unit 17. And the lossy-compressed luminance signal and the color difference signal relating to the reference tone conversion curve from the compression unit 21 as a main body of the image and the losslessly-compressed difference signal from the compression unit 21 and the thumbnail The thumbnail image from the creating unit 23 and information for identifying the luminance signal are stored in the header, and a predetermined file format (for example, JPEG) is stored. An output unit 22 as output means for generating an image file of a reduced file format and outputting it for recording on, for example, a memory card, etc., and a liquid crystal panel or a power switch for displaying the thumbnail image generated by the thumbnail generation unit 23 In addition to acquiring the external I / F unit 24 having a mode switch and the like for switching the shutter button, the shooting mode, and the like, the photometric information from the photometric evaluation unit 8 and the in-focus information from the in-focus detection unit 9 are acquired. The interpolation unit 11, the shooting situation estimation unit 15, the conversion curve calculation unit 16, the gradation conversion unit 17, the Y / C separation unit 18, the compression unit 21, the output unit 22, the thumbnail creation unit 23, the external I / F unit 24, It is a control means consisting of a microcomputer etc. that is connected in both directions and comprehensively controls this imaging system including these, and generates header information And a control unit 25 that also serves as an erasing unit and an output control unit.

  Next, a signal flow in the imaging system as shown in FIG. 1 will be described.

  This imaging system enters a pre-imaging mode by half-pressing a shutter button consisting of a two-stage push button switch.

  A video signal photographed and output by the primary color single-plate CCD 4 through the lens system 1, aperture 2 and low-pass filter 3 is converted into a digital signal by the A / D converter 5, and the first image buffer 6 Transferred to and stored. In the present embodiment, it is assumed that the gradation width of the signal digitized by the A / D converter 5 is, for example, 12 bits.

  The video signal in the pre-imaging mode stored in the first image buffer 6 is transferred to the photometric evaluation unit 8 and the in-focus detection unit 9, respectively.

  The photometric evaluation unit 8 obtains the luminance level in the video signal and controls the aperture value by the aperture 2, the electronic shutter speed of the CCD 4 and the like so as to achieve proper exposure.

  The focus detection unit 9 detects the edge intensity of the video signal, and controls the AF motor 10 so that the edge intensity is maximized to obtain a focused image.

  The photometric information from the photometric evaluation unit 8 and the in-focus information from the in-focus detection unit 9 are also transferred to the control unit 25.

  When the preparation for the main photographing is completed by performing the operation in the pre-imaging mode, the main photographing is performed when it is detected that the shutter button is fully pressed.

  When the actual photographing operation is started, the first video signal is obtained under an exposure condition such that the exposure ratio obtained by the photometric evaluation unit 8 is a predetermined exposure ratio, for example, an exposure ratio of 1/8. (Short exposure image) is taken. The short-time exposure image is converted into a digital signal by the A / D converter 5 and then transferred to the second image buffer 7 and stored therein.

  Subsequently, the second image (long-time exposure image) is taken under the exposure condition obtained by the photometric evaluation unit 8 and converted into a digital signal by the A / D converter 5, and then the first image buffer. 6 to be stored.

  Based on the control of the control unit 25, the interpolation unit 11 performs the single-panel video signal stored in the first image buffer 6 and the single-panel video stored in the second image buffer 7. The signals are sequentially read, and known interpolation processing, white balance processing, enhancement processing, and the like are performed to generate a three-plate video signal, which is transferred to the combining unit 12.

  As described in Japanese Patent Application Laid-Open No. 2001-238128, the combining unit 12 combines a proper exposure area for a short-time exposure image and a proper exposure area for a long-time exposure image, so that one wide dynamic range is obtained. Video signal is generated.

  The wide dynamic range video signal generated by the synthesizer 12 is transferred to the work buffer 13 and stored therein.

  As described above, in this embodiment, the gradation width of the digitized signal is 12 bits, and the exposure ratio between the short-time exposure image and the long-time exposure image is 1: 8 (that is, a shift of 3 bits). The gradation width of the synthesized video signal is 15 bits.

  After the transfer of the wide dynamic range video signal to the work buffer 13, the control unit 25 controls the photographing state estimation unit 15 and the conversion curve calculation unit 16 to execute processing.

  First, as described in Japanese Patent Laid-Open No. 2001-238128, the shooting situation estimation unit 15 determines whether a shooting scene is landscape shooting based on photometric information and focus information acquired via the control unit 25. In addition to these, it is estimated whether the image is a person image or a close-up image, and in addition, whether or not the image is backlit.

  Next, the conversion curve calculation unit 16 reads a reference gradation conversion curve from the reference curve ROM 14 and also reads information at the time of shooting estimated by the shooting state estimation unit 15 as described above.

  Then, the conversion curve calculation unit 16 first transfers the reference gradation conversion curve read from the reference curve ROM 14 to the gradation conversion unit 17 without change.

  Next, the conversion curve calculation unit 16 generates one or more different gradation conversion curves by multiplying the reference gradation conversion curve by a predetermined coefficient, and transfers it to the gradation conversion unit 17. To do.

  The gradation conversion curve calculated by the conversion curve calculation unit 16 will be described with reference to FIG.

  In the example shown in FIG. 2, one or more different gradation conversion curves are generated by multiplying a reference gradation conversion curve TC0 as indicated by a solid line by one or more types of coefficients. Yes. For example, the gradation conversion curve TC + corrected in the positive direction is calculated by multiplying the gradation conversion curve TC0 by 1.2 as a coefficient. Further, the gradation conversion curve TC− corrected in the minus direction is calculated by multiplying the gradation conversion curve TC0 by 0.8 as a coefficient.

  In this way, in this embodiment, a total of three types of tone conversion curves including the reference tone conversion curve are generated.

  The coefficient for multiplying the reference gradation conversion curve as described above is not fixed to 1.2 or 0.8, but based on the shooting situation estimated by the shooting situation estimation unit 15. The conversion curve calculation unit 16 can adaptively change the conversion curve.

  For example, when the shooting scene is a landscape or the like, it is assumed that the dynamic range of the video signal is wide. Therefore, in such a case, it is conceivable to generate and use a gradation conversion curve corrected in the negative direction. On the other hand, when the shooting scene is a person or the like, since the dynamic range of the video signal is assumed to be narrow, it is preferable to generate and use a gradation conversion curve corrected in the positive direction. Furthermore, when it is estimated that the photographic scene is in the backlight state, it may be possible to generate a gradation conversion curve that is corrected to a larger positive direction. By generating such an adaptive tone conversion curve, a higher quality video signal can be obtained.

  Further, a coefficient for multiplying a reference gradation conversion curve may be arbitrarily set manually by the photographer via the external I / F unit 24. Furthermore, the gradation conversion curve is not limited to being generated by multiplying by a coefficient, but can be set so that a photographer manually has a desired curve shape.

  As described above, the gradation conversion curve generated or passed by the conversion curve calculation unit 16 is transferred to the gradation conversion unit 17 at a predetermined timing based on the control of the control unit 25.

  The gradation conversion unit 17 reads the gradation conversion curve transferred from the conversion curve calculation unit 16 based on the control of the control unit 25 and stores, for example, the 15-bit wide dynamic range stored in the work buffer 13. The video signal is converted into a video signal having a gradation width of an output system, for example, an 8-bit gradation width.

  The video signal converted by the gradation conversion unit 17 is transferred to the Y / C separation unit 18 and the thumbnail creation unit 23, respectively.

  In addition, the control unit 25 acquires identification information when the gradation conversion curve is generated from the conversion curve calculation unit 16. For example, in the example shown in FIG. 2, the identification information includes the tone conversion curve obtained by multiplying the reference tone conversion curve by the factor 1.2, the tone conversion curve corrected by the coefficient 1.2, and the coefficient. This is information including a gradation conversion curve that has been multiplied by 0.8 and corrected in the negative direction, which is based on which video signal is generated, its coefficient value, and the like. Then, the control unit 25 transfers this identification information to the output unit 22.

  Note that the conversion curve first used in the gradation conversion unit 17 is set to be a reference gradation conversion curve.

Next, based on the control of the control unit 25, the Y / C separation unit 18 converts the video signal after gradation conversion transferred from the gradation conversion unit 17 into a luminance signal Y as shown in the following Equation 1. And color difference signals Cb and Cr.
[Equation 1]
Y = 0.29900R + 0.58700G + 0.11400B
Cb = −0.16874R−0.33126G + 0.50000B
Cr = 0.50000R-0.41869G-0.0811B

  Then, the Y / C separation unit 18 converts both the luminance signal Y and the color difference signals Cb and Cr with respect to the video signal converted by the reference gradation conversion curve, and the non-reference gradation conversion curve. Only the luminance signal Y is transferred to and stored in the output buffer 19 for the video signal converted by the above.

  The luminance difference calculation unit 20 reads the luminance signal corresponding to the reference gradation conversion curve and the luminance signal corresponding to the non-reference gradation conversion curve from the output buffer 19 and takes the difference between them. As a result, a difference signal is generated as a luminance related signal and transferred to the compression unit 21.

  Under the control of the control unit 25, the compression unit 21 reads out the luminance signal and the color difference signal corresponding to the reference gradation conversion curve from the output buffer 19, and uses a known compression method such as JPEG (Joint Photographic Experts). Compressed using lossy compression such as (Group), and transferred to the output unit 22.

  Next, the compression unit 21 compresses the difference signal transferred from the luminance difference calculation unit 20 using a known compression method, for example, lossless compression such as a Huffman code, and transfers the compressed signal to the output unit 22. By using such a lossless compression, the difference signal in the original uncompressed state can be reliably restored without losing information. In addition, since the luminance signal corresponding to the reference gradation conversion curve and the luminance signal corresponding to the non-reference gradation conversion curve are highly correlated, even if reversible compression is used, the compression is relatively high. The rate can be expected.

  Here, a signal flow based on the above-described processing will be described with reference to FIG.

  FIG. 3A shows a state of a video signal generated by the gradation conversion unit 17 using a reference gradation conversion curve transferred via the conversion curve calculation unit 16.

3B, 3C, and 3D show the luminance signal Y ₁ and the color difference signal generated by the Y / C separation unit 18 from the video signal as shown in FIG. 3A. The states of Cb ₁ and color difference signal Cr ₁ are shown.

  On the other hand, FIG. 3E shows a case where the gradation conversion unit 17 uses a non-standard gradation conversion curve (here, a gradation conversion curve corrected in the plus direction) generated by the conversion curve calculation unit 16. The state of the generated video signal is shown.

FIG. 3F shows the state of the luminance signal Y ₂ generated by the Y / C separation unit 18 from the video signal as shown in FIG. 3 (G) and 3 (H) show the color difference signals when it is assumed that the Y / C separation unit 18 has generated the image signal as shown in FIG. 3 (E). The states of Cb ₂ and color difference signal Cr ₂ are shown. The color difference signals Cb ₂ and Cr ₂ shown in FIGS. 3G and 3H are not actually calculated in this embodiment, but are shown here for easy understanding.

On the other hand, FIG. 3 (I) is calculated by the luminance difference calculation unit 20 based on the luminance signal Y ₁ as shown in FIG. 3 (B) and the luminance signal Y ₂ as shown in FIG. 3 (F). The state of the difference signal is shown.

FIG. 3J shows the luminance signal Y ₁ as shown in FIG. 3B, the color difference signal Cb ₁ as shown in FIG. The color difference signal Cr ₁ as shown in (D) is irreversibly compressed, and the difference signal Y ₁ -Y ₂ as shown in FIG. 3 (I) is reversibly compressed.

  In addition, FIG. 3K shows that the video signal from the compression unit 21 is output as a file by the output unit 22.

  On the other hand, the thumbnail creating unit 23 creates a thumbnail image by reducing the video signal transferred from the gradation converting unit 17 to a predetermined size. This thumbnail image is created for each gradation conversion curve, outputted to the output unit 22, and transferred to the external I / F unit 24 as necessary.

  Under the control of the control unit 25, the output unit 22 uses a predetermined file format (in this embodiment, assuming JPEG compression) for the compressed luminance signal and color difference signal corresponding to the reference gradation conversion curve. Therefore, the file is saved in the JPEG compression file format) as described above.

  Further, the output unit 22 outputs a luminance related signal corresponding to a non-reference gradation conversion curve (that is, a luminance signal from a reference gradation conversion curve, a luminance signal corresponding to a non-reference gradation conversion curve, and The difference signal is further reversibly compressed as described above), the identification information for identifying the luminance signal, and the thumbnail image are stored in a format to be added to the header portion.

  In the above description, the luminance signal obtained based on the reference gradation conversion curve is saved, and the difference signal between the luminance signal and the luminance signal obtained based on the non-reference gradation conversion curve is saved. However, the present invention is not limited to this. For example, the luminance signal itself obtained based on a non-standard gradation conversion curve can be stored as luminance related information.

  Alternatively, when the photographer selects one thumbnail image from among these thumbnail images by displaying thumbnail images corresponding to various gradation conversion curves after shooting, the corresponding thumbnail image is selected. It is also possible to store only the luminance signal and the luminance related signal.

  Such processing will be described with reference to an example of the configuration of the external I / F unit 24 as shown in FIG.

  The external I / F unit 24 shown in FIG. 4 is a display means that can display the thumbnail image created by the thumbnail creation unit 23 and can also display various information related to the imaging system. Liquid crystal panel 31, liquid crystal on / off switch 32 for switching between display and non-display of the liquid crystal panel 31, and a coefficient for generating a non-reference gradation conversion curve based on, for example, a reference gradation conversion curve And the like, a selection key 34 as thumbnail selection means used when selecting one of a plurality of thumbnail images displayed side by side on the liquid crystal panel 31, and the selection key 34. And a confirmation switch 35 as thumbnail selection means for confirming the thumbnail image selected by the above as a selection target.

  Next, processing using such an external I / F unit 24 is as follows.

  After shooting, when a list of shot files is displayed on the liquid crystal panel 31 or the like and one file is selected from the displayed list, various levels stored in the header portion of the file are displayed. A plurality of thumbnail images corresponding to the tone conversion curve are displayed on the liquid crystal panel 31.

  For example, in the example shown in FIG. 4, the thumbnail image related to the reference gradation conversion curve is in the center, the thumbnail image related to the reference gradation conversion curve that has been positively corrected by the coefficient 1.2 is on the right, and the coefficient 0. Thumbnail images related to the reference gradation conversion curve subjected to minus correction by 8 are displayed side by side on the left side.

  In this state, when the photographer operates the selection key 34, a red frame or the like for indicating the selected thumbnail image moves. Thus, after the red frame is moved to the position of the desired thumbnail image, the selection of the thumbnail image surrounded by the red frame is determined by operating the confirmation switch 35.

  Here, for example, it is assumed that a thumbnail image related to the reference gradation conversion curve subjected to plus correction is selected. Then, the information of the selected thumbnail image is transferred from the external I / F unit 24 to the control unit 25.

  The control unit 25 controls the output unit 22 to delete the unselected thumbnail image and delete the difference signal and identification information related to the non-selected gradation conversion curve that is not selected. That is, in this example, the thumbnail image related to the reference gradation conversion curve for which minus correction has been performed and its identification information are deleted.

  As a result, the information recorded on the recording medium or the like remains as the luminance signal and color difference signal related to the reference gradation conversion curve, the selected thumbnail image, and the difference signal and identification related to the selected thumbnail image. Become information. Note that when the selected thumbnail image is related to the reference gradation conversion curve, the difference signal and the identification information are not particularly recorded.

  By performing such processing, it is possible to increase the efficiency of the recording capacity of the recording medium, that is, to save memory. In addition, since an image can be selected while observing an image with a thumbnail image, the imaging system has excellent operability and usability.

  In the above description, it is assumed that processing is performed by hardware. However, the present invention is not limited to this, and processing by software is also possible.

  With reference to FIG. 5, the process performed by the imaging program in the computer will be described. This processing includes, for example, a notebook personal computer having a camera unit for electronic imaging, a desktop personal computer to which a camera for electronic imaging is connected, or a similar camera unit. It can be widely executed in various devices including mobile phones and portable information terminals.

  When the process is started, first, an image obtained by pre-imaging is acquired (step S1).

  Based on the acquired image data obtained by pre-imaging, photographing conditions such as AE (photometry information) and AF (focusing information) in the main photographing are determined (step S2).

  The first image (short-time exposure image) is acquired under a shooting condition set to a predetermined exposure ratio, for example, an exposure ratio of 1/8 with respect to the shooting condition set in step S2 (step S3). ).

  Next, a second image (long exposure image) is acquired based on the photographing condition set in step S2 (step S4).

  Then, the short-time exposure image acquired in step S3 and the long-time exposure image acquired in step S4 are subjected to known interpolation processing, white balance processing, enhancement processing, and the like to generate a three-plate video signal. Further, by combining the proper exposure area of the short-time exposure image after processing and the proper exposure area of the long-time exposure image after processing, a single video signal having a wide dynamic range is generated (step S5). .

  On the other hand, based on the photometry information and the in-focus information acquired in step S2, whether the shooting scene is landscape shooting, portrait shooting, close-up shooting, or the like, and whether the shooting scene is backlit. An estimation of whether or not is made (step S6).

  Then, a reference gradation conversion curve is acquired (step S7), and based on the acquired reference gradation conversion curve and the shooting situation estimated in step S6, as shown in FIG. A plurality of gradation conversion curves including the reference gradation conversion curve are calculated (step S8). Further, the identification information when the gradation conversion curve is generated in step S8 is used in the process of step S17 described later.

  Based on the gradation conversion curve calculated in step S8, the wide dynamic range video signal synthesized in step S5 is subjected to gradation conversion processing to generate an output-system gradation width video signal (step S9). . In the process of step S9, the process using the reference gradation conversion curve is first performed prior to the process using the non-reference gradation conversion curve.

  Next, the generated video signal is separated into a luminance signal and a color difference signal (step S10), and a thumbnail image is created based on the video signal (step S11).

  Subsequently, it is determined whether or not the currently processed video signal is a video signal based on the conversion based on the reference gradation conversion curve (step S12).

  Here, in the case of the video signal related to the reference gradation conversion curve, the luminance signal and the color difference signal separated in step S10 are irreversibly compressed, for example, JPEG compression (step S13).

  In step S12, if the video signal is related to a non-standard gradation conversion curve, the luminance signal based on the non-standard gradation conversion curve separated in step S10 is obtained prior to this. A difference signal from the luminance signal based on the gradation conversion curve serving as a reference is calculated (step S14).

  Then, the calculated difference signal is compressed by lossless compression, such as Huffman code (step S15).

  When the process of step S13 or step S15 is completed, it is determined whether or not a predetermined number of gradation conversions have been performed (step S16). If not yet performed, the process proceeds to step S9 and other steps are performed. The above-described processing is performed based on the gradation conversion curve.

  Thus, if it is determined in step S16 that the prescribed number of gradation conversions has been performed, the luminance signal and color difference signal based on the reference gradation conversion curve that has been irreversibly compressed by the processing in step S13, and the above step The difference signal related to the luminance signal based on the non-standard gradation conversion curve reversibly compressed by the processes of S14 and S15, the thumbnail image created by the process of Step S11, and the gradation conversion by the process of Step S8. Each information including the identification information when the curve is generated is integrated into one file (step S17).

  Then, the generated file is output (step S18), and this series of processing ends.

  In the above description, difference information is calculated for a luminance signal obtained based on a non-standard gradation conversion curve, and is output after being reversibly compressed. However, the present invention is not limited to this. For example, irreversible compression such as JPEG compression can be performed. In this case, although the image quality is lowered, there is an advantage that the size of the output file can be further reduced.

  Further, as described above, not only the difference information is calculated, but it is also possible to perform the same compression process as that of a normal luminance signal such as JPEG compression without changing the luminance signal. In this case, the configuration of the luminance difference calculation unit 20 can be omitted. Further, when performing the reproduction process, there is an advantage that the reproduction can be performed in the same processing time by the same processing circuit as the normal reproduction process only by selecting the compressed luminance signal. Furthermore, when performing the processing for storing the luminance signal other than the reference gradation conversion curve as the difference information as described above, it is necessary to leave the luminance signal corresponding to the reference gradation conversion curve. If the luminance signal is stored instead, the luminance signal corresponding to the reference gradation conversion curve can also be deleted. Thus, the recording medium can be used more efficiently.

  According to the first embodiment, it is possible to generate an output file including luminance information based on a plurality of gradation conversion curves. At this time, since only the luminance signal is stored for the video signal obtained based on the gradation conversion curve outside the reference, it is possible to reduce the size of the output file and save memory. Further, since the difference signal between the luminance signal related to the non-reference gradation conversion curve and the luminance signal related to the reference gradation conversion curve is generated and compressed, the size of the output file is reduced. It can be made smaller.

  Since each stored luminance signal is generated from the gradation width at the time of input, gradation discontinuity occurs regardless of which of the plurality of gradation conversion curves is selected. No high-quality video signal can be obtained.

  In addition, since the gradation conversion is directly performed on the original signal, the processing system can be simplified, and the imaging system can be configured at low cost.

  In addition, since a plurality of images with different exposures are combined to generate a video signal with a wide dynamic range, a wide dynamic range that exceeds the gradation width of an image obtained by a single image pickup with a normal image sensor. An image can be obtained.

  In addition, since the reference gradation conversion curve is recorded on the ROM, setting is easy and high-speed processing is possible.

  In addition, since the non-reference gradation conversion curve is calculated from the reference gradation conversion curve, various gradation conversion curves can be generated quickly and easily.

  On the other hand, when the tone conversion curve is calculated for each image by estimating the situation at the time of shooting, it is possible to generate a high-quality video signal more suitable for each image.

  Furthermore, since the information for identifying the luminance signal and the thumbnail image corresponding to each gradation conversion curve are stored in one file, the operability at the time of identifying and selecting the image is excellent. A system can be configured.

  Since the luminance signal and color difference signal corresponding to the reference gradation conversion curve are recorded in the file in accordance with a predetermined compression file format, compatibility with conventional image files is maintained, and high versatility is achieved. It will have.

  6 to 10 show a second embodiment of the present invention, FIG. 6 is a block diagram showing the configuration of the imaging system, FIG. 7 is a block diagram showing the configuration of the limit setting unit, and FIG. 8 is a limit setting unit. FIG. 9 is a diagram for explaining correction of the saturation signal in the YCbCr color space, and FIG. 10 is a block diagram showing the configuration of the color difference correction unit.

  In the second embodiment, the same parts as those of the first embodiment are denoted by the same reference numerals and the description thereof is omitted, and only different points will be mainly described.

  As shown in FIG. 6, the imaging system according to the second embodiment includes an image buffer 41 instead of the first image buffer 6 and the second image buffer 7 according to the first embodiment described above. The composition unit 12, the shooting state estimation unit 15, the thumbnail creation unit 23, and the external I / F unit 24 are deleted, and an edge extraction unit 42, a histogram creation unit 43, a limit setting unit 44, and a color difference correction unit 45 are added. It has become.

  The image buffer 41 temporarily stores the digitized video signal from the A / D converter 5, and depends on whether the video signal is obtained by pre-imaging or main imaging. As described above, the data is appropriately output to the photometric evaluation unit 8, the in-focus detection unit 9, and the interpolation unit 11.

  The video signal interpolated by the interpolation unit 11 is transferred to the Y / C separation unit 18 via the work buffer 13.

  The edge extraction unit 42 is a feature amount calculation unit, and extracts an edge component as a feature amount based on the luminance signal separated by the Y / C separation unit 18.

  The histogram creation unit 43 is a histogram creation unit, creates a histogram based on the edge component extracted by the edge extraction unit 42 and the luminance signal separated by the Y / C separation unit 18, and This is output to the conversion curve calculation unit 16.

  The restriction setting unit 44 is a restriction unit, and corrects the conversion curve calculated by the conversion curve calculation unit 16 based on a reference gradation conversion curve read from the reference curve ROM 14.

  The gradation conversion unit 17 performs gradation conversion on the luminance signal separated by the Y / C separation unit 18 based on the reference gradation conversion curve transferred from the reference curve ROM 14 via the restriction setting unit 44. At the same time, gradation conversion is performed based on the gradation conversion curve corrected by the restriction setting unit 44 and output to the output buffer 19. In addition, the luminance signal subjected to gradation conversion by the reference gradation conversion curve is also output to the color difference correction unit 45.

  The color difference correction unit 45 is a color difference correction unit, and the color difference signal separated by the Y / C separation unit 18 is subjected to gradation correction based on a reference gradation conversion curve from the gradation correction unit 17. The luminance signal is corrected and output to the output buffer 19.

  The control unit 25 is also bidirectionally connected to the edge extraction unit 42, the histogram creation unit 43, the restriction setting unit 44, and the color difference correction unit 45, and controls them.

  Next, in the imaging system as shown in FIG. 6, the signal flow different from that of the imaging system as shown in FIG. 1 is almost as follows.

  The analog video signal output from the CCD 4 is converted into a digital signal by the A / D converter 5 and transferred to and stored in the image buffer 41. Also in this embodiment, it is assumed that the gradation width of the signal digitized by the A / D converter 5 is, for example, 12 bits.

  Based on the control of the control unit 25, the interpolation unit 11 reads a single-panel video signal stored in the image buffer 41, performs known interpolation processing, white balance processing, enhancement processing, etc. The video signal is generated and transferred to the work buffer 13.

  Based on the control of the control unit 25, the Y / C separation unit 18 separates the video signal transferred from the work buffer 13 into the luminance signal Y and the color difference signals Cb and Cr according to the above formula 1.

  Based on the control of the control unit 25, the edge extraction unit 42 extracts edge components by performing edge extraction processing such as known Laplacian processing on the luminance signal Y transferred from the Y / C separation unit 18. The obtained edge component is transferred to the histogram creation unit 43.

  The histogram creation unit 43 reads the edge information from the edge extraction unit 42 and the luminance signal Y from the Y / C separation unit 18 based on the control of the control unit 25, and accumulates the pixels with a predetermined edge strength or higher. A histogram is calculated, and the calculated cumulative histogram is transferred to the conversion curve calculation unit 16.

  Based on the control of the control unit 25, the conversion curve calculation unit 16 generates an adaptive gradation conversion curve by normalizing the cumulative histogram from the histogram creation unit 43, and limits the generated gradation conversion curve. Transfer to the setting unit 44.

  The gradation conversion curve generated here has a gradation conversion characteristic that maintains the gradation width of the video signal at the time of input. That is, in this embodiment, as described above, the level of the video signal at the time of input is set. Since it is assumed that the adjustment width is 12 bits, the gradation conversion characteristics have a 12-bit gradation width after conversion.

  The restriction setting unit 44 reads a reference gradation conversion curve from the reference curve ROM 14 and also reads an adaptive gradation conversion curve from the conversion curve calculation unit 16 to become a reference to the adaptive gradation conversion curve. Impose restrictions based on tone conversion curves.

  Then, the restriction-adapted gradation conversion curve (non-reference gradation conversion curve) and the reference gradation conversion curve from the reference curve ROM 14 are sent from the restriction setting unit 44 to the gradation conversion unit 17. Forwarded to

  Based on the control of the control unit 25, the gradation conversion unit 17 first performs gradation conversion processing on the luminance signal Y from the Y / C separation unit 18 using a reference gradation conversion curve, and then the restriction is applied. The luminance signal Y from the Y / C separation unit 18 is subjected to gradation conversion processing using the imposed adaptive gradation conversion curve, and each processed luminance signal is transferred to the output buffer 19 and a reference floor is obtained. The luminance signal Y subjected to gradation conversion based on the tone conversion curve is also transferred to the color difference correction unit 45.

  Based on the control of the control unit 25, the color difference correction unit 45 performs a correction process on the color difference signal when the reference gradation conversion curve is used in the gradation conversion unit 17.

This correction processing includes a luminance signal after gradation conversion (hereinafter referred to as Y _tra ) based on a reference gradation conversion curve from the gradation conversion unit 17 and luminance at the time of input from the Y / C separation unit 18. Based on the signal (hereinafter referred to as Y _org ), a correction coefficient for the color difference signal is calculated, and this correction coefficient is converted into a color difference signal (hereinafter referred to as Cb and Cr corresponding to Cb and Cr) from the Y / C separation unit 18. _org , Cr _org ).

The corrected color difference signals (hereinafter referred to as Cb _tra and Cr _tra ) are transferred to the output buffer 19 while maintaining the gradation width of the video signal at the time of input (that is, 12 bits in this embodiment as described above). The

  After the processing as described above is performed in this way, the output buffer 19 receives the luminance signal corresponding to the reference gradation conversion curve from the gradation conversion unit 17 and the restriction from the gradation conversion unit 17. A luminance signal corresponding to the imposed adaptive gradation conversion curve (non-reference gradation conversion curve) and a corrected color difference signal corresponding to the reference gradation conversion curve from the color difference correction unit 45; Will exist.

  The luminance difference calculation unit 20 reads out from the output buffer 19 the luminance signal corresponding to the reference gradation conversion curve and the luminance signal corresponding to the non-reference gradation conversion curve, and these difference signals. Is calculated as difference information.

  Based on the control of the control unit 25, the compression unit 21 has a luminance signal and a color difference signal corresponding to a reference gradation conversion curve stored in the output buffer 19, a difference signal from the luminance difference calculation unit 20, and Is converted into a signal having a gradation width of the output system (for example, a gradation width of 8 bits). This conversion is performed by a simple division process. In this embodiment, the conversion is performed by shifting 12 bits to 8 bits by 4 bits.

  Next, the compression unit 21 compresses the luminance signal and the color difference signal corresponding to the reference gradation conversion curve obtained by converting the gradation width by a known compression method (for example, JPEG) and transfers the compressed signal to the output unit 22. .

  Further, the compression unit 21 compresses the difference signal (luminance related information) from the luminance difference calculation unit 20 stored in the output buffer 19 by a known compression method (for example, a lossless compression method such as a Huffman code). , And transfer to the output unit 22.

  Under the control of the control unit 25, the output unit 22 uses a normal file format (assuming JPEG compression also in this embodiment) for the compressed luminance signal and color difference signal corresponding to the reference gradation conversion curve. Therefore, the file is saved in the JPEG compression file format).

  Furthermore, the compressed difference signal related to the luminance signal corresponding to the non-reference gradation conversion curve and the identification information for identifying the luminance signal are stored in a format to be added to the header part.

  Next, an example of the configuration of the restriction setting unit 44 will be described with reference to FIG.

  The limit setting unit 44 includes a distance calculation unit 51 that calculates a distance between an adaptive gradation conversion curve from the conversion curve calculation unit 16 and a reference gradation conversion curve from the reference curve ROM 14, and the distance. Based on the distance information calculated by the calculation unit 51, the adaptive tone conversion curve from the conversion curve calculation unit 16 is corrected so that the distance is within a predetermined range, and the corrected adaptive level is corrected. A distance correction unit 52 that outputs the tone conversion curve and the reference gradation conversion curve transferred from the distance calculation unit 51 to the gradation conversion unit 17 is provided.

  The control unit 25 is connected bidirectionally to the distance calculation unit 51 and the distance correction unit 52 and controls them.

  The processing flow of the restriction setting unit 44 as shown in FIG. 7 is as follows.

  The distance calculation unit 51 reads an adaptive tone conversion curve from the conversion curve calculation unit 16, and also reads a reference tone conversion curve from the reference curve ROM 14, and adaptively calculates the reference tone conversion curve from the reference tone conversion curve. The distance l of the gradation conversion curve is calculated. The calculation of the distance l is sequentially performed along the input axis, and the adaptive gradation conversion curve is corrected based on the calculated distance l.

Assuming that the adaptive gradation conversion curve from the conversion curve calculation unit 16 is T and the reference gradation conversion curve from the reference curve ROM 14 is T ₀ , the distance l is as shown in Equation 2 below. Is calculated as follows.
[Equation 2]
l = Max (when l> Max)
l = 1 (when l <1)
l = | T−T ₀ | (Otherwise)
Here, “Max” is a predetermined constant term (for example, 128 when the gradation width is 12 bits).

Further, the gradation conversion curve T ′ corrected by the distance correcting unit 52 is calculated as shown in the following Equation 3.
[Equation 3]
T ′ = T ₀ + (T−T ₀ ) {1 + 1 (k−1) / Max}
Here, k is a predetermined constant term (a constant that satisfies 0 <k <1 and is, for example, 0.4).

FIG. 8 shows an example when correction by such processing is performed, and an adaptive tone conversion curve T from the conversion curve calculation unit 16 as indicated by a thin line is indicated by a dotted line. It can be seen that the tone conversion curve T ′ is corrected so as to be closer to the reference tone conversion curve T ₀ and becomes a corrected tone conversion curve T ′ as indicated by a thick line.

  The tone conversion curve corrected by the limit setting unit 44 is transferred to the tone conversion unit 17.

  Since the correction method as described above is continuously performed based on the distance from the reference gradation conversion curve, there is an advantage that the discontinuity of the gradation change due to the correction does not occur.

  Next, the concept of the color difference signal correction method in the color difference correction unit 45 will be described with reference to FIG.

First, the luminance signal V, the hue signal H, and the saturation signal C are calculated based on the luminance signal Y and the color difference signals Cb and Cr as shown in the following Expression 4.
[Equation 4]
V = Y
H = tan ⁻¹ (Cb / Cr)
C = (Cb · Cb + Cr · Cr) ^1/2

  Since the luminance signal V in Equation 4 is the same as the luminance signal Y calculated by Equation 1, the symbol “Y” is hereinafter used for the luminance signal.

Now, the luminance signal at the time of input from the Y / C separation unit 18 is represented by Y _org , and the color difference signal at the time of input from the Y / C separation unit 18 is represented by Cb _org and Cr _org , and the corresponding hue signal is represented by H _org , a saturation signal is represented by C _org , and a luminance signal subjected to gradation conversion based on a gradation conversion curve serving as a reference by the gradation conversion unit 17 is represented by Y _tra . Further, the theoretical limit characteristic of color reproduction in the YCbCr color space as shown in FIG. 9, that is, a function indicating the maximum saturation is represented by maxC.

  To obtain a visually unnatural color when the luminance signal changes, it is necessary to correct the saturation signal so that the hue signal is constant and the ratio to the maximum saturation is maintained. There is.

Therefore, first, the maximum saturation for the luminance signal Y _org at the time of input is determined as maxC _org, and then the maximum saturation for the converted luminance signal Y _tra is determined as maxC _tra .

Then, the correction coefficient k _C for _obtaining the saturation signal C _tra corresponding to the converted luminance signal Y _tra is calculated as shown in Equation 5 below.
[Equation 5]
k _C = maxC _tra / maxC _org

By multiplying the saturation signal C _org by such a correction coefficient k _C , a corrected saturation signal C _tra can be obtained.

The corrected color difference signals Cb _tra and Cr _tra can be obtained based on the following Equation 6 using the saturation signal C _tra corrected by performing such an operation and the hue H _org. .
[Equation 6]
Cb _tra = C _tra · sin (H _org )
Cr _tra = C _tra · cos (H _org )

The corrected color difference signals Cb _tra and Cr _tra calculated in this way are transferred to the output buffer 19.

  An example of the configuration of the color difference correction unit 45 for performing the processing as described above will be described with reference to FIG.

The color difference correction unit 45 is based on the function recording ROM 62 in which the function maxC indicating the maximum saturation is recorded and the color difference signals Cb _org and Cr _org from the Y / C separation unit 18 as shown in the above formula 4. a hue signal H _org and the hue saturation calculating unit 63 for calculating a chroma signal C _org, the luminance signal Y from the hue signal H _org and the Y / C separation unit 18 calculated by the hue saturation calculating portion 63 _The maximum saturation maxC _org is calculated by referring to the function recording ROM 62 corresponding to _org, and the hue signal H _org and the luminance signal Y _tra after gradation conversion from the gradation conversion unit 17 are calculated. a maximum color saturation calculation unit 61 that calculates a maximum chroma maxC _tra by referring to the function number recording ROM62 correspondingly, the maximum saturation maxC _org calculated by the maximum color saturation calculation unit 61, based on maxC _tra Z Chroma signal C _org from the ratio calculation unit 64 and, the hue saturation calculating unit 63 the correction coefficient k _C calculated by the ratio calculation unit 64 for calculating a correction coefficient k _C as shown in Equation 5 Te It said on the basis of a multiplication unit 65 for calculating the corrected chroma signal C _tra by multiplying the hue signal H _org from the chroma signal C _tra and the hue saturation calculating unit 63 from the multiplication unit 65 to the A color difference calculation unit 66 that calculates the color difference signals Cb _tra and Cr _tra corrected by the mathematical formula 6 and outputs them to the output buffer 19.

  The control unit 25 is bidirectionally connected to the maximum saturation calculation unit 61, the hue saturation calculation unit 63, the ratio calculation unit 64, the multiplication unit 65, and the color difference calculation unit 66, and controls them. It is supposed to be.

  The Y / C separator 18 is also connected to the multiplier 65.

  The processing flow of the color difference correction unit 45 as shown in FIG. 10 is as follows.

The hue saturation calculation unit 63 reads the color difference signals Cb _org and Cr _org corresponding to the input signal from the Y / C separation unit 18 based on the control of the control unit 25, and uses the above Equation 4 to calculate the hue signal H _org. The saturation signal C _org is calculated, the calculated hue signal H _org is transferred to the maximum saturation calculation unit 61 and the color difference calculation unit 66, and the calculated saturation signal C _org is transferred to the multiplication unit 65. .

Based on the control of the control unit 25, the maximum saturation calculation unit 61 converts the luminance signal Y _org at the time of input from the Y / C separation unit 18 to the gradation based on the reference gradation conversion curve from the gradation conversion unit 17. The converted luminance signal Y _tra is read from the hue saturation calculation unit 63 as the hue signal H _org . Next, the maximum saturation calculation unit 61 reads the function maxC indicating the maximum saturation as shown in FIG. 9 from the function recording ROM 62, and when the hue signal is H _org and the luminance signal is Y _org. determine the maximum saturation maxC _org corresponding. Further, the maximum saturation calculation unit 61 obtains the maximum saturation maxC _tra corresponding to the case where the hue signal is H _org and the luminance signal is Y _tra based on the function maxC read from the function recording ROM 62. Then, the maximum saturation calculation unit 61 transfers the obtained maximum saturations maxC _org and maxC _tra to the ratio calculation unit 64.

Based on the control of the control unit 25, the ratio calculation unit 64 uses the maximum saturation maxC _org and maxC _tra transferred from the maximum saturation calculation unit 61 to calculate the correction coefficient k _{C according} to the above equation 5, and calculates the calculated correction The coefficient k _C is transferred to the multiplication unit 65.

The multiplication unit 65 multiplies C _org from the hue saturation calculation unit 63 by the correction coefficient k _C from the ratio calculation unit 64 to generate a corrected saturation signal C _tra, thereby generating a color difference calculation unit 66. Forward to.

The color difference calculation unit 66 reads the corrected saturation signal C _tra from the multiplication unit 65, and also reads the hue signal H _org from the hue saturation calculation unit 63, and corrects the corrected color difference signal Cb _tra based on Equation 6 above. , Cr _tra are obtained, and the obtained color difference signals Cb _tra , Cr _tra are transferred to the output buffer 19.

  In the above description, the compression unit 21 converts a 12-bit signal into an 8-bit signal. However, the present invention is not limited to this. For example, it is possible to perform a compression process with 12 bits. In this case, the versatility of the compressed file is reduced, but higher-speed processing can be performed.

Furthermore, in the above description, the gradation conversion unit 17 performs gradation conversion that maintains the gradation width (specifically, gradation conversion from 12 bits to 12 bits), but is not limited thereto. . For example, the gradation conversion may be performed using a gradation conversion curve that simultaneously converts the gradation width from 12 bits to 8 bits. In this case, the color difference correction unit 45 performs processing after shifting the 12-bit luminance signal Y _org at the time of input from the Y / C separation unit 18 by 4 bits to convert it into an 8-bit luminance signal. As a result, maxC _org is calculated based on the 8-bit luminance signal Y _org , and maxC _tra is calculated based on the 8-bit luminance signal Y _tra . In this case, although the accuracy of saturation correction is slightly lowered, the accuracy of the function recorded in the function recording ROM 62 is 8 bits, so that the ROM capacity can be saved. As for the color difference signal, the color difference signals Cb _org and Cr _org input from the Y / C separation unit 18 are converted into an 8-bit color difference signal by shifting, for example, 4 bits or converting the bit width linearly. Can be converted. By using such an 8-bit color difference signal, the saturation signal C _org and the hue signal H _org may be calculated in 8 bits. As a result, the subsequent processing in the color difference correction unit 45 can be performed in 8 bits together with the luminance signal Y _org converted into 8 bits as described above.

  As described above, the conversion of the gradation width can be performed by the gradation conversion unit 17 and the color difference correction unit 45, or may be performed by the compression unit 21, or may be performed by both of them, or other circuits. It is also possible to carry out in part, and is not particularly limited.

  According to the second embodiment, it is possible to generate an output file including luminance information based on a plurality of gradation conversion curves. At this time, since only the luminance signal is stored for the video signal obtained based on the gradation conversion curve outside the reference, it is possible to reduce the size of the output file and save memory. Further, since the difference signal between the luminance signal related to the non-reference gradation conversion curve and the luminance signal related to the reference gradation conversion curve is generated and compressed, the size of the output file is reduced. It can be made smaller.

  Since each stored luminance signal is generated from the gradation width at the time of input, gradation discontinuity occurs regardless of which of the plurality of gradation conversion curves is selected. No high-quality video signal can be obtained.

  In addition, since the gradation conversion is performed only on the luminance signal, the processing for the luminance signal and the processing for the color difference signal can be separated, and an imaging system capable of obtaining a high-quality video signal can be configured. It becomes possible.

  At this time, since the color difference signal is corrected using the original luminance signal and the gradation-converted luminance signal, a high-quality color can be maintained.

  Further, since the reference gradation conversion curve is recorded on the ROM, the setting is easy and high-speed processing is possible.

  In addition, since the non-standard gradation conversion curve is adaptively generated for each image based on the histogram, it is possible to generate a higher-quality video signal suitable for each image.

  In addition, when generating a non-standard gradation conversion curve, a restriction is imposed based on the reference gradation conversion curve, so that the image does not break down and a stable image quality is more reliably obtained. Can get to.

  In addition, since the information for identifying the luminance signal is stored in one file, it is possible to configure a system that is excellent in operability when identifying or selecting an image.

  Furthermore, since the luminance signal and color difference signal corresponding to the reference gradation conversion curve are recorded in the file in accordance with a predetermined compression file format, compatibility with conventional image files is maintained, and high versatility is achieved. It will have.

  FIGS. 11 and 12 show a third embodiment of the present invention. FIG. 11 is a block diagram showing the configuration of a playback system. FIG. 12 is a flowchart showing processing performed by a playback program in a computer.

  In the third embodiment, the description of the same parts as in the first and second embodiments will be omitted, and only different points will be mainly described.

  The reproduction system of the present embodiment is used, for example, when reproducing an image file imaged by the imaging system of the first embodiment described above.

  This playback system includes an input unit 71 for inputting an image file as described above from a recording medium such as a memory card, and all the thumbnail images included in the header portion of the image file via the input unit 71. The identification information for identifying the luminance signal is read out and output to a monitor or the like of the output unit 79 to be described later for display, etc., and the external I / O to be described later with reference to the monitor display and the like. Controls and reads data read from the input unit 71 according to the thumbnail image selected by the user via the F unit 80, and inputs information other than the information related to the selected thumbnail image as necessary. A selection / erasure unit 72 serving as an erasure unit and a luminance signal selection unit for controlling the input unit 71 that can be erased. A decompression unit 74 as decompression means for decompressing the compressed data input from the input unit 71 via the erasure unit 72, an output buffer 75 for temporarily storing the image data decompressed by the decompression unit 74, and the output When the luminance signal read from the buffer 75 is a difference signal (luminance related signal) based on a gradation conversion curve other than the reference, a luminance calculation unit 76 that is a luminance calculation unit that calculates an original luminance signal, and the output buffer 75 Color difference correction means for correcting the color difference signal read from the output buffer 75 using the luminance signal calculated by the luminance calculation section 76 when the read luminance signal corresponds to a non-reference gradation conversion curve. The color difference correction unit 77 and the luminance signal calculation unit 76 read the luminance signal and read the color difference signal from the color difference correction unit 77 to obtain an RGB image. A Y / C synthesis unit 78 as a synthesis unit for generating a signal, an output unit 79 as a display unit including a monitor or the like for displaying the RGB video signal generated by the Y / C synthesis unit 78, and a user Is an interface including, for example, a mouse and a keyboard for performing operation input, and is an external I / F unit 80 as a thumbnail selection means bidirectionally connected to the output unit 79, the input unit 71, the selection erasing unit 72, This reproduction system includes a thumbnail reading unit 73, an expansion unit 74, a luminance calculation unit 76, a color difference correction unit 77, a Y / C synthesis unit 78, an output unit 79, and an external I / F unit 80 that are bidirectionally connected. And a control unit 81 which is a control means and a priority means including a microcomputer or the like for controlling the above in an integrated manner.

  Next, the signal flow in the reproduction system as shown in FIG. 11 will be described.

  By attaching a recording medium such as a memory card to an input unit 71 having a reading unit such as a memory card reader, the recording medium is recognized by the control unit 81 and recorded in the recording medium. The read image file can be read out.

  In the image file, as shown in the first embodiment, the luminance signal and the color difference signal obtained based on the reference gradation conversion curve are recorded as the main body of the image, and if necessary, the image file is out of the standard. The difference signal corresponding to the tone conversion curve is recorded in the header part. Further, in the header part, the thumbnail image corresponding to the video signal generated by each tone conversion curve and the luminance signal are stored. Identification information for identification is recorded.

  At this time, the luminance signal and the color difference signal obtained based on the reference gradation conversion curve are recorded in a predetermined compression format, which is a format based on JPEG compression, which is lossy compression in this embodiment.

  Furthermore, the difference signal corresponding to the non-standard gradation conversion curve is recorded in a compressed state using a known compression method, for example, lossless compression such as a Huffman code.

  The thumbnail reading unit 73 reads all thumbnail images included in the header unit and identification information for identifying all luminance signals based on the control of the control unit 81, and monitors the output unit 79. Forward to.

  At this time, the output unit 79 corrects from the thumbnail image related to the reference gradation conversion curve subjected to minus correction to the thumbnail image related to the reference gradation conversion curve subjected to plus correction based on the identification information. Are arranged in the order of the coefficients used in the above, and are displayed on the monitor. Thereby, a plurality of thumbnail images are displayed on the monitor, for example, in the same manner as that shown in FIG. 4 of the first embodiment described above.

  A user who sees the display on such a monitor selects one of the thumbnail images via the external I / F unit 80 such as a mouse or a keyboard.

  The control unit 81 detects an operation in the external I / F unit 80 and transfers information related to the selected thumbnail image to the selection erasing unit 72.

  When the selected thumbnail image is a thumbnail image corresponding to an image obtained based on the reference gradation conversion curve, the selection / erasure unit 72 corresponds to the reference gradation conversion curve from the input unit 71. Read the compressed luminance signal and color difference signal.

  On the other hand, if the selected thumbnail image is a thumbnail image corresponding to an image obtained based on a non-standard gradation conversion curve, the selection / erasure unit 72 receives a reference gradation conversion curve from the input unit 71. And a compressed luminance signal and color difference signal corresponding to the above and a reversibly compressed difference signal (luminance related signal) for the selected thumbnail image are read.

  Thus, the signal read from the input unit 71 by the selective erasure unit 72 is transferred to the decompression unit 74.

  Under the control of the control unit 81, the decompression unit 74 performs predetermined decompression processing, in this embodiment JPEG decompression processing, on the luminance signal and color difference signal corresponding to the reference gradation conversion curve, The expanded signal is transferred to the output buffer 75.

  Further, when a thumbnail image obtained based on a non-standard gradation conversion curve is selected, the expansion unit 74 performs JPEG expansion on the luminance signal and the color difference signal related to the reference gradation conversion curve as described above. In addition to the processing, a predetermined decompression process for the reversibly compressed difference signal (luminance-related signal), in this embodiment, a decompression process for the Huffman code is also performed, and the decompressed difference signal is also sent to the output buffer 75. Forward.

  Based on the control of the control unit 81, the luminance calculation unit 76, when the luminance signal stored in the output buffer 75 is a luminance signal corresponding to the reference gradation conversion curve, If the luminance signal stored in the output buffer 75 is a difference signal corresponding to a non-reference gradation conversion curve, the luminance signal corresponding to the reference gradation conversion curve is added. Thus, a normal luminance signal is calculated and transferred to the Y / C synthesis unit 78.

  On the other hand, the color difference correction unit 77 reads the color difference signal stored in the output buffer 75 based on the control of the control unit 81, and the luminance signal stored in the output buffer corresponding to the color difference signal is the reference value. Y / C after correcting the chrominance signal as it is when it corresponds to the tone conversion curve, and after correcting the chrominance signal when it corresponds to the non-reference tone conversion curve. Transfer to the combining unit 78.

The correction of the color difference signal by the color difference correction unit 77 is to obtain corrected color difference signals Cb _tra and Cr _tra in the same manner as described with reference to FIGS. 9 and 10 in the second embodiment. . However, in the processing of the color difference correction unit 77, the luminance signal corresponding to the reference gradation conversion curve is Y _org , the color difference signal corresponding to the reference gradation conversion curve is Cb _org , Cr _org , The luminance signal corresponding to the non-standard gradation conversion curve is Y _tra .

Based on the luminance signal Y from the luminance calculation unit 76 and the color difference signals Cb and Cr from the color difference correction unit 77, the Y / C synthesis unit 78 converts the primary color system video signals R, G, and B into the following formulas. Synthesis is performed as shown in FIG.
[Equation 7]
R = Y + 1.40200Cr
G = Y−0.34414Cb−0.71414Cr
B = Y + 1.77200 Cb

  The video signal synthesized by the Y / C synthesis unit 78 is transferred to the output unit 79 and displayed on the monitor.

  In addition, by deleting unnecessary information other than the image related to the selected thumbnail image, it is also possible to organize the storage contents of a recording medium such as a memory card attached to the input unit 71.

  Such erasure processing is performed by the selective erasure unit 72 based on the control of the control unit 81.

  That is, the selection erasure unit 72 acquires information related to the selected thumbnail image from the control unit 81. Then, the selection erasure unit 72 erases thumbnail images other than the selected thumbnail image, unnecessary luminance information, and information for identifying the luminance signal.

  Here, the unnecessary luminance information or the like excludes the luminance information corresponding to the reference gradation conversion curve and the difference signal corresponding to the selected thumbnail image when the luminance related information is a difference signal. It is a difference signal other than that. Therefore, when a thumbnail image corresponding to a non-reference gradation conversion curve is selected, all the difference signals relating to the thumbnail images that are not selected are erased, and a thumbnail image corresponding to the reference gradation conversion curve is displayed. When selected, all difference signals are erased.

  In addition, as described in the first embodiment, in the case where the luminance related information is the luminance signal itself, it becomes a reference when a thumbnail image corresponding to a non-reference gradation conversion curve is selected. The luminance signal corresponding to the gradation conversion curve is also deleted.

  As a result, unnecessary information can be erased from the recording medium, so that the recording medium can be used efficiently (memory saving).

  In the above description, it is assumed that processing is performed by hardware. However, the present invention is not limited to this, and processing by software is also possible.

  With reference to FIG. 12, the process performed by the reproduction program in the computer will be described. This processing can be executed by, for example, a general personal computer having a display device such as a monitor, and can also be widely executed by computers having other display functions and arithmetic processing functions. is there.

  When the processing is started, first, the luminance signal and color difference signal obtained based on the reference gradation conversion curve and compressed, the thumbnail image recorded in the header portion, and the reference recorded in the header portion are excluded. Various types of information including a difference signal of the reversibly compressed luminance signal obtained based on the gradation conversion curve and identification information for identifying the luminance signal recorded in the header portion are read (step S21). .

  Next, all thumbnail images are extracted from the read information (step S22), and the extracted thumbnail images are displayed on the monitor (step S23).

  When the user who sees the monitor display selects one of the thumbnail images using a mouse, a keyboard, or the like (step S24), first, a compressed luminance signal obtained based on a reference gradation conversion curve is obtained. Then, the color difference signal is extracted (step S25), and the extracted luminance signal and color difference signal are expanded (step S26).

  Subsequently, it is determined whether or not the thumbnail image selected in step S24 corresponds to a non-reference gradation conversion curve (step S27).

  Here, if it is determined that it corresponds to a non-standard gradation conversion curve, a luminance related signal consisting of a reversibly compressed difference signal corresponding to the selected thumbnail image is extracted (step S28). ), The difference signal compressed in a lossless manner is expanded to calculate a difference signal (difference luminance signal) in an uncompressed state (step S29).

  Then, a luminance signal corresponding to the selected thumbnail image is calculated using the difference signal calculated in step S29 and the luminance signal obtained based on the reference gradation conversion curve (step S30). .

  Next, using the luminance signal obtained based on the reference gradation conversion curve and the luminance signal corresponding to the selected thumbnail image, the color difference signal obtained based on the reference gradation conversion curve is obtained. In the second embodiment described above, correction is performed in substantially the same manner as that described with reference to FIGS. 9 and 10 (step S31).

  When the process of step S31 ends or when it is determined that the thumbnail image selected in step S27 corresponds to the reference gradation conversion curve, the following process is performed.

  First, when the thumbnail image selected in step S24 corresponds to the reference gradation conversion curve, the video signal is generated by synthesizing the luminance signal and the color difference signal expanded in step S26. . On the other hand, if the thumbnail image selected in step S24 corresponds to a non-standard gradation conversion curve, the luminance signal calculated in step S30 and the color difference signal corrected in step S31 are used. The synthesized video signal is generated (step S32).

  Thereafter, the video signal generated in this way is output (step S33), and this series of processing ends.

  In the above description, first, all thumbnail images are displayed on a monitor or the like, and after the thumbnail image is selected by the user who sees the monitor display, the reproduction processing of the image related to the selected thumbnail image is performed. However, it is not limited to such processing. For example, without performing an operation such as selection, first, the control unit 81 may preferentially set the video signal corresponding to the reference gradation conversion curve as the standard condition and automatically perform the reproduction process. good. Thereby, since the process is automated, it is possible to efficiently perform the confirmation work.

  According to the third embodiment, for example, data is read from a recording medium on which an image file as shown in the first embodiment is recorded, and one of luminance signals corresponding to a plurality of gradation conversion characteristics is selected. The selected luminance signal and color difference signal can be expanded to generate and reproduce a video signal.

  At this time, since the color difference signal is common and only the luminance signal needs to be switched to perform the reproduction process, it is possible to reproduce the processing results for a plurality of gradation conversion characteristics easily and at high speed.

  In addition, since the luminance signal can be selected while viewing the displayed thumbnail image, it is possible to easily select the processing result based on the different gradation conversion curves while observing it visually. An excellent playback system can be constructed.

  Furthermore, when a luminance signal corresponding to a gradation conversion curve other than the reference is selected, the color difference signal is corrected and used, so that a high-quality video signal with natural color reproduction can be obtained.

  In each of the above-described embodiments, the imaging system, the imaging program, the playback system, and the playback program are described. However, the imaging method to which the processing by the imaging system and the imaging program is applied, or the processing by the playback system and the playback program is applied. The playback method may be used.

  Furthermore, the imaging reproduction system may be configured by combining the imaging system and the reproduction system as described above, or the imaging reproduction program is configured by combining the imaging program and the reproduction program as described above. Alternatively, it is also possible to combine the imaging method and the reproduction method as described above to obtain an imaging reproduction method.

  For example, in the case of an imaging / reproducing system, an example in which an imaging / reproducing system in which image data is acquired by the imaging system of the first embodiment and reproduced by the reproducing system of the third embodiment described above can be considered. Alternatively, it is also possible to configure the imaging / reproducing system by a combination in which image data is acquired by the imaging system of the second embodiment described above and reproduced by a reproducing system that reproduces the image data in substantially the same manner. .

  Similarly, it is also possible to configure an imaging reproduction program in which image data is acquired by the imaging program of the first embodiment described above and is reproduced by the reproduction program of the third embodiment described above. An imaging reproduction program or an imaging reproduction method almost corresponding to Example 3 is also possible.

  In addition, this invention is not limited to the Example mentioned above, Of course, a various deformation | transformation and application are possible within the range which does not deviate from the main point of invention.

  The present invention can be widely applied when imaging, reproducing, processing, etc., video signals related to a plurality of gradation conversion characteristics.

1 is a block diagram showing a configuration of an imaging system in Embodiment 1 of the present invention. FIG. 6 is a diagram showing a plurality of gradation conversion curves in the first embodiment. FIG. 6 is a diagram showing a procedure for generating an output file based on image data generated by different gradation conversion curves in the first embodiment. FIG. 3 is a diagram illustrating a configuration example of an external I / F unit in the first embodiment. 5 is a flowchart illustrating processing performed by an imaging program in the computer according to the first embodiment. The block diagram which shows the structure of the imaging system in Example 2 of this invention. The block diagram which shows the structure of the restriction | limiting setting part in the said Example 2. FIG. The diagram which shows a mode that a gradation conversion curve is corrected by the restriction | limiting setting part of the said Example 2. FIG. In the said Example 2, the figure for demonstrating correction | amendment of the saturation signal in YCbCr color space. FIG. 5 is a block diagram illustrating a configuration of a color difference correction unit in the second embodiment. The block diagram which shows the structure of the reproduction | regeneration system in Example 3 of this invention. 10 is a flowchart illustrating processing performed by a reproduction program in the computer according to the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Lens system 2 ... Aperture 3 ... Low pass filter 4 ... CCD (image sensor)
DESCRIPTION OF SYMBOLS 5 ... A / D converter 6 ... 1st image buffer 7 ... 2nd image buffer 8 ... Photometry evaluation part 9 ... In-focus detection part 10 ... AF motor 11 ... Interpolation part 12 ... Synthesis | combination part (synthesis | combination means)
13 ... Working buffer 14 ... Reference curve ROM (recording means)
15 ... Shooting condition estimation unit (estimating means)
16: Conversion curve calculation unit (tone conversion curve calculation means)
17 ... gradation conversion section (gradation conversion means)
18 ... Y / C separation part (separation means)
19 ... output buffer 20 ... luminance difference calculation unit (luminance difference calculation means)
21: Compression unit (compression means)
22: Output unit (output means)
23 ... Thumbnail creation unit (thumbnail generation means)
24 ... External I / F unit 25 ... Control unit (header information generating unit, erasing unit, output control unit)
31 ... Liquid crystal panel (display means)
32 ... LCD ON / OFF switch 33 ... Numeric key 34 ... Select key (thumbnail selection means)
35 ... Confirm switch (thumbnail selection means)
41 ... Image buffer 42 ... Edge extraction unit (feature amount calculation means)
43 ... Histogram creation unit (histogram creation means)
44 ... Limit setting unit (limit means)
45. Color difference correction unit (color difference correction means)
DESCRIPTION OF SYMBOLS 51 ... Distance calculation part 52 ... Distance correction part 61 ... Maximum saturation calculation part 62 ... ROM for function recording
63 ... Hue / Saturation Calculation Unit 64 ... Ratio Calculation Unit 65 ... Multiplication Unit 66 ... Color Difference Calculation Unit 71 ... Input Unit 72 ... Selection Erase Unit (Erase Unit, Luminance Signal Select Unit)
73 ... Thumbnail reading section (reading means)
74 ... Extension part (extension means)
75: Output buffer 76: Luminance calculation unit (luminance calculation means)
77 ... Color difference correction unit (color difference correction means)
78 ... Y / C synthesis section (synthesis means)
79... Output section (display means)
80 ... External I / F section (thumbnail selection means)
81 ... Control unit (priority means)
Agent Patent Attorney Susumu Ito

Claims (34)

A video signal having Mbit (M is a natural number) gradation width from the imaging system is output based on a gradation conversion curve as a predetermined reference, and Nbit of the output system (N is a natural number and satisfies M ≧ N). To a video signal having an N-bit gradation width of the output system based on a gradation conversion curve outside the reference different from the reference gradation conversion curve. Gradation conversion means for conversion;
Separating means for separating the video signal converted by the gradation converting means into a luminance signal and a color difference signal;
Compression that compresses the luminance signal and color difference signal obtained based on the reference gradation conversion curve and the luminance-related signal related to the luminance signal obtained based on the non-reference gradation conversion curve, if necessary. Means,
An imaging system comprising: Separating means for separating a video signal having a gradation width of Mbit (M is a natural number) from the imaging system into a luminance signal and a color difference signal;
The luminance signal having the Mbit gradation width separated by the separating means has a gradation width of Nbit (N is a natural number and satisfies M ≧ N) based on a predetermined reference gradation conversion curve. Gradation conversion means for converting to a luminance signal and, if necessary, converting to a luminance signal having a gradation width of Nbit based on a gradation conversion curve other than the reference, which is different from the reference gradation conversion curve. ,
The color difference signal having the Mbit gradation width separated by the separation means is converted into the color difference signal having the Nbit gradation width, and the luminance signal separated by the separation means and the reference by the gradation conversion means. A luminance difference converted based on the tone conversion curve to be corrected using,
A luminance signal obtained based on the reference gradation conversion curve and the corrected color difference signal, and, if necessary, a luminance related signal related to the luminance signal obtained based on the non-reference gradation conversion curve; Compression means for compressing
An imaging system comprising:   The imaging system according to claim 1, wherein the luminance-related signal is a luminance signal itself obtained based on a gradation conversion curve that is out of a reference. The luminance-related signal is a difference signal that is a difference between a luminance signal obtained based on the reference gradation conversion curve and a luminance signal obtained based on the non-reference gradation conversion curve,
The imaging system according to claim 1, further comprising a luminance difference calculation unit for calculating the difference signal as necessary.   By synthesizing at least two images composed of video signals having a gradation width of kbit (k is a natural number and satisfying M ≧ k) obtained by imaging the same subject under different exposure conditions 5. The imaging system according to claim 1, further comprising a synthesizing unit that generates a video signal having the Mbit gradation width.   The imaging system according to any one of claims 1 to 5, wherein the gradation converting means includes recording means for recording a reference gradation conversion curve. .   The gradation conversion means further comprises gradation conversion curve calculation means for calculating the non-reference gradation conversion curve based on the reference gradation conversion curve. The imaging system according to claim 6. Further comprising an estimation means for estimating the shooting situation,
The imaging according to claim 7, wherein the gradation conversion curve calculation unit is configured to vary the non-reference gradation conversion curve to be calculated in accordance with a shooting situation estimated by the estimation unit. system. The gradation converting means is
A feature amount calculating means for calculating a feature amount with respect to the video signal or the luminance signal;
A histogram creating means for creating a histogram based on the feature amount;
A gradation conversion curve calculating means for calculating a gradation conversion curve based on the histogram;
Limiting means for calculating a non-standard gradation conversion curve by imposing a restriction on the gradation conversion curve calculated by the gradation conversion curve calculating means based on the reference gradation conversion curve;
The imaging system according to claim 7, further comprising: Generating identification information for identifying a luminance signal obtained based on the reference gradation conversion curve and a luminance related signal related to the luminance signal obtained based on the non-reference gradation conversion curve; Header information generating means for generating header information so as to include the generated identification information;
Output means for outputting at least one of the compressed luminance signal and the compressed luminance-related signal, the compressed color difference signal, and the header information as one file;
The imaging system according to any one of claims 1 to 5, further comprising:   The imaging system according to any one of claims 1 to 5, further comprising thumbnail generation means for generating a thumbnail image of a predetermined size based on the video signal subjected to gradation conversion. Generating identification information for identifying a luminance signal obtained based on the reference gradation conversion curve and a luminance related signal related to the luminance signal obtained based on the non-reference gradation conversion curve; Header information generating means for generating header information so as to include the generated identification information and the thumbnail image;
Output means for outputting at least one of the compressed luminance signal and the compressed luminance-related signal, the compressed color difference signal, and the header information as one file;
The imaging system according to claim 11, further comprising:   The imaging system according to claim 11, further comprising display means for displaying the thumbnail image.   14. The imaging system according to claim 13, further comprising thumbnail selection means for selecting the thumbnail image displayed on the display means.   At least one of a compressed luminance signal and a compressed luminance related signal related to the thumbnail image selected by the thumbnail selection means, and a compressed color difference signal corresponding to the reference gradation conversion curve. The imaging system according to claim 14, further comprising output means for outputting as one file.   15. The apparatus according to claim 14, further comprising an erasing unit for erasing a luminance signal and / or luminance related signal other than the luminance signal and / or luminance related signal related to the thumbnail image selected by the thumbnail selection unit. The imaging system described in 1.   17. The imaging system according to claim 16, wherein the erasing unit is further configured to erase thumbnail images other than the thumbnail image selected by the thumbnail selecting unit.   It further comprises output control means for controlling the output means so that luminance related information relating to the luminance signal obtained based on the non-standard gradation conversion curve is added to the header information and output. The imaging system according to claim 10 or 12. It includes a luminance signal obtained and compressed based on the reference gradation conversion characteristics, a compressed color difference signal, and header information, and is different from the reference gradation conversion curve if necessary. A reproduction system that decompresses and outputs a compressed signal portion of a signal that further includes a compressed luminance related signal related to the luminance signal obtained based on the gradation conversion curve of:
A luminance signal selecting means for selecting at least one of the compressed luminance signal and the compressed luminance related signal based on the header information;
Expansion means for expanding the luminance signal and / or the luminance related signal selected by the luminance signal selection means, and the color difference signal;
Synthesizing means for synthesizing a video signal based on the luminance signal and / or luminance related signal and color difference signal expanded by the expansion means;
A playback system comprising:   20. The luminance signal selecting means comprises priority means for preferentially selecting a compressed luminance signal corresponding to a reference gradation conversion characteristic. Playback system. The header information is configured to include a thumbnail image,
The luminance signal selection means includes
Reading means for reading a thumbnail image included in the header information;
Display means for displaying the thumbnail images read by the reading means;
Thumbnail selection means for selecting a thumbnail image displayed on the display means;
Priority means for preferentially selecting a compressed luminance signal and / or luminance related signal corresponding to the thumbnail image selected by the thumbnail selection means;
The playback system according to claim 19, wherein the playback system is configured to include:   The luminance signal selecting unit further includes an erasing unit for erasing a luminance signal and / or luminance related signal other than the luminance signal and / or luminance related signal related to the thumbnail image selected by the thumbnail selecting unit. The playback system according to claim 21, wherein the playback system is configured.   23. The playback system according to claim 22, wherein the erasing unit is further configured to erase thumbnail images other than the thumbnail image selected by the thumbnail selection unit.   The synthesizing means includes color difference correction means for correcting the color difference signal expanded by the expansion means when a luminance related signal corresponding to a gradation conversion characteristic other than the reference is selected by the luminance signal selection means. The playback system according to claim 19, wherein the playback system is configured as described above. The luminance-related signal is a difference signal that is a difference between a luminance signal obtained based on the reference gradation conversion curve and a luminance signal obtained based on the non-reference gradation conversion curve,
When the luminance-related signal is selected by the luminance signal selection unit, the synthesizing unit converts the luminance-related signal expanded by the expansion unit into the reference gradation conversion curve expanded by the expansion unit. A luminance calculation means for calculating a luminance signal obtained on the basis of the non-standard gradation conversion curve by adding the luminance signals obtained on the basis of the above is provided. Item 20. The playback system according to Item 19. A video signal having Mbit (M is a natural number) gradation width from the imaging system is output based on a gradation conversion curve as a predetermined reference, and Nbit of the output system (N is a natural number and satisfies M ≧ N). To a video signal having an N-bit gradation width of the output system based on a gradation conversion curve outside the reference different from the reference gradation conversion curve. Tone conversion procedure to convert,
A separation procedure for separating the video signal converted by the gradation conversion procedure into a luminance signal and a color difference signal;
Compression that compresses the luminance signal and color difference signal obtained based on the reference gradation conversion curve and the luminance-related signal related to the luminance signal obtained based on the non-reference gradation conversion curve, if necessary. Procedure and
An imaging method comprising: A separation procedure for separating a video signal having a gradation width of Mbit (M is a natural number) from the imaging system into a luminance signal and a color difference signal;
The luminance signal having the Mbit gradation width separated by the separation procedure has a gradation width of Nbit (N is a natural number and satisfies M ≧ N) based on a predetermined reference gradation conversion curve. A gradation conversion procedure for converting into a luminance signal and, if necessary, converting into a luminance signal having a gradation width of the Nbit based on a gradation conversion curve other than the reference, which is different from the reference gradation conversion curve. ,
The color difference signal having the Mbit gradation width separated by the separation procedure is converted into the color difference signal having the Nbit gradation width, the luminance signal separated by the separation procedure, and the reference by the gradation conversion procedure. A luminance signal converted based on the gradation conversion curve to be corrected using a color difference correction procedure;
A luminance signal obtained based on the reference gradation conversion curve and the corrected color difference signal, and, if necessary, a luminance related signal related to the luminance signal obtained based on the non-reference gradation conversion curve; Compression procedure to compress
An imaging method comprising: It includes a luminance signal obtained and compressed based on the reference gradation conversion characteristics, a compressed color difference signal, and header information, and is different from the reference gradation conversion curve if necessary. A reproduction program for expanding and outputting a compressed signal portion of a signal further including a compressed luminance related signal related to a luminance signal obtained based on the gradation conversion curve of
On the computer,
A luminance signal selection procedure for selecting at least one of the compressed luminance signal and the compressed luminance related signal based on the header information;
A decompression procedure for decompressing the luminance signal and / or the luminance related signal selected by the luminance signal selection procedure and the color difference signal;
A synthesis procedure for synthesizing a video signal based on the luminance signal and / or the luminance-related signal and the color difference signal expanded by the expansion procedure;
A playback program for running. The header information is configured to include a thumbnail image,
The luminance signal selection procedure is as follows:
A reading procedure for reading a thumbnail image included in the header information;
A display procedure for displaying the thumbnail image read by the reading procedure;
A thumbnail selection procedure for selecting a thumbnail image displayed by the above display procedure;
A priority procedure for preferentially selecting a compressed luminance signal and / or luminance related signal corresponding to the thumbnail image selected by the thumbnail selection procedure;
The reproduction program according to claim 28, comprising:   The synthesis procedure includes a color difference correction procedure for correcting the color difference signal expanded by the expansion procedure when a luminance related signal corresponding to a gradation conversion characteristic other than the reference is selected by the luminance signal selection procedure. The reproduction program according to claim 28, characterized in that: A video signal having Mbit (M is a natural number) gradation width from the imaging system is output based on a gradation conversion curve as a predetermined reference, and Nbit of the output system (N is a natural number and satisfies M ≧ N). To a video signal having an N-bit gradation width of the output system based on a gradation conversion curve outside the reference different from the reference gradation conversion curve. Gradation conversion means for conversion;
Separating means for separating the video signal converted by the gradation converting means into a luminance signal and a color difference signal;
Compression that compresses the luminance signal and color difference signal obtained based on the reference gradation conversion curve and the luminance-related signal related to the luminance signal obtained based on the non-reference gradation conversion curve, if necessary. Means,
Generating identification information for identifying a luminance signal obtained based on the reference gradation conversion curve and a luminance related signal related to the luminance signal obtained based on the non-reference gradation conversion curve; Header information generating means for generating header information so as to include the generated identification information;
An imaging system comprising:
A luminance signal selecting means for selecting at least one of the compressed luminance signal and the compressed luminance related signal based on the header information;
Expansion means for expanding the luminance signal and / or the luminance related signal selected by the luminance signal selection means, and the color difference signal;
Synthesizing means for synthesizing a video signal based on the luminance signal and / or luminance related signal and color difference signal expanded by the expansion means;
A playback system with
An imaging reproduction system comprising: Separating means for separating a video signal having a gradation width of Mbit (M is a natural number) from the imaging system into a luminance signal and a color difference signal;
The luminance signal having the Mbit gradation width separated by the separating means has a gradation width of Nbit (N is a natural number and satisfies M ≧ N) based on a predetermined reference gradation conversion curve. Gradation conversion means for converting to a luminance signal and, if necessary, converting to a luminance signal having a gradation width of Nbit based on a gradation conversion curve other than the reference, which is different from the reference gradation conversion curve. ,
The color difference signal having the Mbit gradation width separated by the separation means is converted into the color difference signal having the Nbit gradation width, and the luminance signal separated by the separation means and the reference by the gradation conversion means. A luminance difference converted based on the tone conversion curve to be corrected using,
A luminance signal obtained based on the reference gradation conversion curve and the corrected color difference signal, and, if necessary, a luminance related signal related to the luminance signal obtained based on the non-reference gradation conversion curve; Compression means for compressing
Generating identification information for identifying a luminance signal obtained based on the reference gradation conversion curve and a luminance related signal related to the luminance signal obtained based on the non-reference gradation conversion curve; Header information generating means for generating header information so as to include the generated identification information;
An imaging system comprising:
A luminance signal selecting means for selecting at least one of the compressed luminance signal and the compressed luminance related signal based on the header information;
Expansion means for expanding the luminance signal and / or the luminance related signal selected by the luminance signal selection means, and the color difference signal;
Synthesizing means for synthesizing a video signal based on the luminance signal and / or luminance related signal and color difference signal expanded by the expansion means;
A playback system with
An imaging reproduction system comprising: On the computer,
A video signal having Mbit (M is a natural number) gradation width from the imaging system is output based on a gradation conversion curve as a predetermined reference, and Nbit of the output system (N is a natural number and satisfies M ≧ N). To a video signal having an N-bit gradation width of the output system based on a gradation conversion curve outside the reference different from the reference gradation conversion curve. Tone conversion procedure to convert,
A separation procedure for separating the video signal converted by the gradation conversion procedure into a luminance signal and a color difference signal;
Compression that compresses the luminance signal and color difference signal obtained based on the reference gradation conversion curve and the luminance-related signal related to the luminance signal obtained based on the non-reference gradation conversion curve, if necessary. procedure,
Generating identification information for identifying a luminance signal obtained based on the reference gradation conversion curve and a luminance related signal related to the luminance signal obtained based on the non-reference gradation conversion curve; Header information generation procedure for generating header information to include the generated identification information,
A luminance signal selection procedure for selecting at least one of the compressed luminance signal and the compressed luminance related signal based on the header information;
A decompression procedure for decompressing the luminance signal and / or the luminance related signal selected by the luminance signal selection procedure and the color difference signal;
A synthesis procedure for synthesizing a video signal based on the luminance signal and / or the luminance-related signal and the color difference signal expanded by the expansion procedure;
An imaging reproduction program for executing On the computer,
A separation procedure for separating a video signal having a gradation width of Mbit (M is a natural number) from the imaging system into a luminance signal and a color difference signal;
The luminance signal having the Mbit gradation width separated by the separation procedure has a gradation width of Nbit (N is a natural number and satisfies M ≧ N) based on a predetermined reference gradation conversion curve. A gradation conversion procedure for converting into a luminance signal and, if necessary, converting into a luminance signal having the Nbit gradation width based on a gradation conversion curve other than the reference, which is different from the reference gradation conversion curve.
The color difference signal having the Mbit gradation width separated by the separation procedure is converted into the color difference signal having the Nbit gradation width, the luminance signal separated by the separation procedure, and the reference by the gradation conversion procedure. A color difference correction procedure for correcting using a luminance signal converted based on a tone conversion curve,
A luminance signal obtained based on the reference gradation conversion curve and the corrected color difference signal, and a luminance related signal related to the luminance signal obtained based on the non-reference gradation conversion curve, if necessary; Compression procedure to compress,
Generating identification information for identifying a luminance signal obtained based on the reference gradation conversion curve and a luminance related signal related to the luminance signal obtained based on the non-reference gradation conversion curve; Header information generation procedure for generating header information to include the generated identification information,
A luminance signal selection procedure for selecting at least one of the compressed luminance signal and the compressed luminance related signal based on the header information;
A decompression procedure for decompressing the luminance signal and / or the luminance related signal selected by the luminance signal selection procedure and the color difference signal;
A synthesis procedure for synthesizing a video signal based on the luminance signal and / or the luminance-related signal and the color difference signal expanded by the expansion procedure;
An imaging reproduction program for executing

Images