JPH11191871A - Image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably prepare the print of high picture quality reproducing an image close to an impression at the time of watching an original scene by performing the compressing processing of the dynamic range of an image corresponding to the compressing conditions of the set dynamic range. SOLUTION: At a processor 10, out-of-focus image data processed by the dynamic range compressing table of a second look-up table(LUT) 82 are added to main image data processed by a first matrix computing element (MTX) 76. Thus, overlaid printing processing is performed while non-linearly compressing the dynamic range of image data, the dynamic range of output image data and the gradation or density of light/dark parts are made proper, and an output image is provided as the print reproducing the image of high picture quality for a person to get the same impression as the time of watching the original (photographed) scene. The dynamic range compressing table of the second LUT 82 is a table for providing processing image data for appropriately compressing the dynamic range or the like of out-of-focus image data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technical field of an image processing apparatus used for a digital photo printer or the like which photoelectrically reads an image photographed on a film and obtains a print (photograph) in which the image is reproduced. Belong.

[0002]

2. Description of the Related Art At present, an image photographed on a photographic film (hereinafter referred to as a film) such as a negative film or a reversal film is printed on a photosensitive material (photographic paper) by projecting an image of the film onto the photosensitive material. Surface-exposing the photosensitive material,
So-called direct exposure (analog exposure) is the mainstream.

On the other hand, in recent years, a printing apparatus using digital exposure, that is, an image recorded on a film is photoelectrically read, the read image is converted into a digital signal, and then various image processing is performed. 2. Description of the Related Art Digital photo printers have been put to practical use, in which image data (latent images) are recorded by scanning and exposing a photosensitive material with recording light modulated in accordance with the image data, and the resulting images are printed.

In a digital photo printer, exposure conditions at the time of printing can be determined by image data processing using an image as digital image data, so that image skipping and blurring caused by backlight, strobe photography, and the like can be corrected, and sharpness can be reduced. Properly perform (sharpening) processing, correction of color feria and density feria, correction of underexposure and overexposure, correction of insufficient peripheral light quantity, etc. to obtain high-quality prints that could not be obtained by conventional direct exposure Can be. In addition, synthesis of a plurality of images, image division, and synthesis of characters can be performed by image data processing, and prints that have been freely edited / processed according to the intended use can be output.
Moreover, according to the digital photo printer, not only can the image be output as a print (photo), but also the image data can be supplied to a computer or the like or stored on a recording medium such as a floppy disk. Can be used for various purposes other than photography.

Such a digital photo printer basically includes a scanner (image reading device) that photoelectrically reads an image recorded on a film, image processing of the read image, and recording image data (exposure conditions). And a printer (image recording apparatus) that scans and exposes the photosensitive material in accordance with the image data, performs development processing, and prints.

In a scanner, reading light emitted from a light source is incident on a film to obtain projection light carrying an image photographed on the film, and the projection light is transmitted to an image sensor such as a CCD sensor by an imaging lens. The image is read by forming an image and performing photoelectric conversion, and after performing various types of image processing as necessary, the image is sent to the image processing apparatus as image data (image data signal) of the film. The image processing apparatus sets image processing conditions from image data read by a scanner, performs image processing according to the set conditions on the image data, and outputs the image data to a printer as output image data (exposure conditions) for image recording. send. In the printer, for example, if the device uses light beam scanning exposure, the light beam is modulated according to the image data sent from the image processing device,
The photosensitive material is two-dimensionally scanned and exposed (printed) to form a latent image, and then subjected to a predetermined developing process and the like, so that an image photographed on the film is reproduced (printed).

[0007]

By the way, the photographing conditions of an image photographed on a film are not constant, and when there is a large difference between light and dark (density) such as a strobe photograph or a backlight scene, that is, the dynamic range of the image is very large. There are many cases where it is wide. When a print is created by exposing such a film image by a normal method, an image in either a bright portion (highlight) or a dark portion (shadow) may be lost. For example, when a person is photographed in backlight, if a person is exposed to obtain a suitable image, a bright portion such as the sky will fly white, and conversely, the exposure will be performed so that the sky will be a suitable image. If you do, the person will be crushed black.

Therefore, when exposing a photosensitive material using a film image having a large brightness as an original image, so-called dodging is performed. Dodging means that normal exposure is applied to parts of intermediate density, bright areas where the image is likely to fly increase the exposure, and dark areas where the image is likely to collapse reduce the exposure on the film. This is a technique for correcting a large brightness of a photographed image and obtaining a print in which an appropriate image is reproduced over the entire screen so as to approximate an impression when a human looks at an original scene.

In a conventional apparatus using direct exposure, a method of performing exposure by inserting a light-shielding plate or an ND filter in an exposure optical path, a method of partially changing the amount of light of an exposure light source, and the method of adjusting the brightness of an image photographed on a film. For example, dodging is performed by partially changing the exposure amount in accordance with an image photographed on a film by, for example, a method in which a monochrome film is formed by reversing the above method, and the exposure is performed by overlapping the monochrome film. On the other hand, in the digital photo printer, the direct exposure is performed by compressing the dynamic range of an image by image data processing so as to appropriately reproduce a bright portion and / or a dark portion (hereinafter referred to as dodging process). It is possible to reproduce an image close to the impression when a human sees the original scene with a higher degree of freedom than dodging in the above-mentioned method. 18704, 9-130609, etc.).

Generally, in digital image data processing, an image photographed on a film is photoelectrically read, and
The obtained image data is analyzed, image processing conditions such as dodging processing are set, and image data processing is performed. However, depending on the scene type of the original image, the luminance of the original scene, and the state of the light rays, an image photographed on a film (an image reproduced from the film) often differs from the impression that a human saw the original scene. For this reason, even if the optimal dodging conditions are set in accordance with the image data, there is a limit to how close the output image can be to the impression when a person views the original scene.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to process image data or the like obtained from an image photographed on a film into image data for output as described above. An image processing apparatus suitably used for a photo printer, which includes a scene type, luminance,
It is possible to set an optimal image processing condition in accordance with the state of light rays at the time of photographing and to perform a compression process of an image dynamic range that gives a dodging effect in direct exposure (dodging process). Regardless, it is an object of the present invention to provide an image processing apparatus capable of stably reproducing an image close to an impression when a human looks at an original scene.

[0012]

According to an aspect of the present invention, there is provided an image processing apparatus for performing predetermined image processing on image data of an image obtained by photographing to obtain output image data. Means for acquiring shooting information of the image, setting means for setting a compression condition of a dynamic range of the image from the image data and the shooting information acquired by the acquiring means, and a dynamic range set by the setting means. Processing means for compressing the dynamic range of the image according to compression conditions.

[0013] Preferably, the setting means sets a compression condition of a dynamic range using an image feature amount calculated from the image data.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image processing apparatus according to the present invention will be described in detail based on a preferred embodiment shown in the accompanying drawings.

FIG. 1 is a block diagram showing an example of a digital photo printer using the image processing apparatus of the present invention. The digital photo printer (hereinafter, referred to as a photo printer 10) shown in FIG. 1 basically includes a scanner (image reading device) 12 that photoelectrically reads an image captured on a film F, and read image data ( An image processing unit 14 that performs image processing of image information), operation and control of the entire photo printer 10, and the like, and imagewise exposes the photosensitive material A with a light beam modulated according to image data output from the image processing unit 14. And a printer 16 for developing and outputting as a (finished) print. Also,
The image processing apparatus 14 includes an operation system 18 having a keyboard 18a and a mouse 18b for inputting (setting) various conditions, selecting and instructing processing, and instructions for color / density correction, and the like. A display 20 for displaying a read image, various operation instructions, a setting / registration screen for various conditions, and the like is connected.

The scanner 12 is a device that photoelectrically reads an image photographed on a film F or the like one frame at a time.
And a variable aperture 24 and R, G and B for separating the image into three primary colors of R (red), G (green) and B (blue).
A color filter plate 26 having a plurality of color filters and rotating to apply an arbitrary color filter to an optical path; a diffusion box 28 for making reading light incident on the film F uniform in a surface direction of the film F; A lens unit 32 and a CCD sensor 3 serving as an area sensor for reading one frame image of the film;
4 and an amplifier (amplifier) 36.

In the illustrated example of the photo printer 10,
Depending on the type and size of the film, such as a new photo system (Advanced Photo System) or 135 size negative (or reversal) film, the form of the film such as strips and slides, etc. The carrier 30 is prepared, and by exchanging the carrier 30, it is possible to cope with various films and processes. An image (frame) photographed on a film and provided for print creation is conveyed and held at a predetermined reading position by the carrier 30. Further, as is well known, a magnetic recording medium is formed on the film of the new photographic system, and a cartridge ID, a film type, and the like are recorded. Various data such as the presence or absence of strobe light emission, imaging magnification, shooting scene ID, information on the position of the main part, and the type of developing machine can be recorded. New photo system film (cartridge)
The magnetic information reading means is arranged on the carrier 30 corresponding to the image processing apparatus 1 and reads the magnetic information when the film is transported to the reading position.
4

In such a scanner 12, the reading light emitted from the light source 22, the amount of light is adjusted by the variable aperture 24, the color is adjusted by passing through the color filter plate 26, and diffused by the diffusion box 28 is transmitted to the carrier 30. As a result, the light enters one frame of the film F held at a predetermined reading position and is transmitted therethrough, thereby obtaining projection light carrying an image of the frame photographed on the film F. The projection light of the film F is formed into an image on the light receiving surface of the CCD sensor 34 by the imaging lens unit 32, is read photoelectrically by the CCD sensor 34, and its output signal is amplified by the amplifier 36 and transmitted to the image processing device 14. Sent. CCD sensor 34
Is, for example, an area CCD sensor having 1380 × 920 pixels.

In the scanner 12, such an image reading is performed three times by sequentially inserting the respective color filters of the color filter plate 26, so that one frame of image is read out by R, G and B.
And read out. Here, in the photo printer 10, a pre-scan for reading an image at a low resolution is performed in order to determine image processing conditions and the like, before reading an image for printing a print (main scan). Therefore, a total of six image readings are performed in one frame.

The scanner 12 uses an area CCD sensor and adjusts reading light with a color filter plate 26 to separate an original image (projection light of the film F) into three primary colors and read the image. As scanners for supplying image data to the image processing apparatus of the present invention, R, G
An image is read by so-called slit scanning, in which three line CCD sensors corresponding to reading of the three primary colors of B and B are used to scan and convey the film F with a carrier while reading an image with slit-shaped reading light (projection light). An image reading device for reading may be used.

The illustrated photo printer 10 uses a scanner 12 that photoelectrically reads an image photographed on a film such as a negative or a reversal as an image data supply source of the image processing device 14. The image data supply source that supplies the image data includes an image pickup device such as a digital camera and a digital video camera, an image reading device that reads an image of a reflection document, and an LA in addition to the scanner 12.
Communication means such as N (Local Area Network) and computer communication network; various image reading means and imaging means such as a memory card and a medium (recording medium) such as MO (magneto-optical recording medium); storage means for image data; Can be used in various ways.

As described above, the output signal (image data) from the scanner 12 is output to the image processing device 14 (hereinafter, referred to as the processing device 14). FIG. 2 shows a block diagram of the processing device 14. The processing device 14 is related to the image processing device of the present invention, and includes a data processing unit 38, a prescan (frame) memory 40, a main scan (frame) memory 42, a condition setting unit 44, a display image processing unit 46, It has a main scan image processing unit 48. FIG. 2 mainly shows parts related to image processing. The processing device 14 includes a CP that controls and manages the entire photo printer 10 including the processing device 14.
U, a memory for storing information necessary for operation of the photo printer 10, etc .;
Means for determining the storage time of the CD sensor 34 and the like are arranged. The operation system 18 and the display 20
It is connected to each part via U etc. (CPU bus).

The R, G, and B output signals output from the scanner 12 are subjected to A / D (analog / digital) conversion, Log conversion, DC offset correction, dark time correction, shading correction, and the like. The pre-scan (image) data is stored in the pre-scan memory 40 in the main scan (image).
The data is stored (stored) in the main scan memory 42, respectively. The pre-scan data and the main scan data are basically the same data except that the resolution (pixel density) and the signal level are different.

The image information stored in the pre-scan memory 40 is read out to the display image processing unit 46 and the condition setting unit 44, and the image information stored in the main scan memory 42 is read out to the main scan image processing unit 48.

The condition setting section 44 has a setup (processing condition setting) section 50, a key correction section 52, and a parameter integration section 54. The setup unit 50 is a part for setting the basic image processing conditions.
From the image data stored in 0, create a density histogram, highlight (highest density), shadow (lowest density),
Image characteristics such as average density and LATD (large area transmission density) are calculated, and image processing conditions are set, specifically, gray balance (color balance) adjustment, image dynamic range compression processing (hereinafter, dodging) For example, a look-up table (LUT) for performing various types of image processing, such as processing, is calculated, and a correction coefficient (processing coefficient) is calculated. here,
In the processing device 14 according to the present invention, the processing conditions of the dodging processing are set in consideration of the acquired photographing information in addition to the image feature amount. These image processing conditions will be described later in detail.

The key correction section 52 calculates the correction amount of the image processing condition in accordance with the instruction (input) of the operator using the adjustment key 56 or the like set on the keyboard 18a shown in FIG. With the adjustment key 56 in the illustrated example, as an example,
Overall density (D), cyan (C) density, magenta density (M), yellow (Y) density, gradation (γ), bright part (highlight α light), and dark part (shadow α dar)
k) can be adjusted individually, and the operator performs the test while viewing the image displayed on the display 20 described later, and presses the (+) key and (-) key of each parameter as necessary. Adjust the image to the desired state,
That is, the image processing conditions are adjusted.

The parameter integration unit 54 is configured to store the image processing conditions set by the setup unit 50 and the key correction unit 5
And the correction amount obtained in Step 2 is integrated to obtain the finally set image processing condition. Therefore, when there is no input from the adjustment key 56, the image processing conditions of the main scan data (output image) are the image processing conditions set by the setup unit 50. When the parameter integration unit 54 integrates and sets the image processing conditions, the parameter integration unit 54 sets the image processing conditions in predetermined portions (hardware) of the display image processing unit 46 and the main scan image processing unit 48, and each image data is set according to the image processing conditions. Process. Therefore, when an input is made from the adjustment key 56 and the image processing condition previously set by the parameter integration unit 54 is changed, the image on the display 20 changes accordingly.

The display image processing section 46 reads out the pre-scan data stored in the pre-scan memory 40, performs image processing in accordance with the image processing conditions set by the condition setting section 44, and outputs image data for display on the display 20. The first LUT 58 and the first matrix computing unit (MT
X) 60, second MTX 62, low-pass filter (LP)
F) 64, a second LUT 66, a third LUT 68, a signal converter 70, and an adder 72. on the other hand,
The main scan image processing unit 48 reads the main scan data stored in the main scan memory 42 and
The first LUT 74, the first MTX 76, the first LUT 74, the first MTX 76, which perform predetermined image processing according to the image processing conditions set in step 4 and output the image data by the printer 16.
Second MTX 78, LPF 80, second LUT 82, third L
It has a UT 84 and an adder 86. Note that the main scan image processing unit 48 may further include a sharpness processing unit that performs a sharpness (sharpening) process.

As apparent from the above description, the two image processing units have almost the same configuration, and basically the same processing conditions are set except that the number of pixels (resolution) is different. Done. Hereinafter, both image processing units will be described using the main scan image processing unit 48 as a representative example.

The first LUT 74 (first LUT 58) reads out image data stored in the main scan memory 42 (pre-scan memory 40), adjusts the gray balance,
It performs brightness (density) correction and gradation correction, and is configured by cascading LUTs for performing respective corrections and adjustments. Each LUT of the first LUT 74 is
It is created and set by the condition setting unit 44 described above.

FIG. 4 shows an example of a table set in the first LUT 74. FIG. 4A shows a gray balance adjustment table. The setup unit 50 creates this adjustment table by taking a gray balance from highlights and shadows by a known method. When an input is made from the adjustment key 56, the correction amount is calculated by the key correction unit 52, and the correction amount and the adjustment table created by the setup unit 50 are integrated by the parameter integration unit 54, and the adjustment table is adjusted. Of the R, G, and B tables change.
FIG. 4B shows a correction table for brightness correction. The setup unit 50 uses a known setup algorithm based on a density histogram, highlights and shadows.
This correction table is created. Also, this correction table is obtained by inputting the density (D) key of the adjustment key 56 as shown in FIG.
Is adjusted as shown in FIG. 4C shows a gradation correction table. The setup unit 50 creates this correction table from a density histogram, highlights and shadows using a known setup algorithm.
Also, this correction table is adjusted as shown in FIG. 4C by inputting the gradation (γ) key of the above-mentioned adjustment key 56, similarly to the gray balance adjustment table.

The first MTX 76 (first MTX 60) corrects the saturation of the image data processed by the first LUT 74. The first MTX 76 (first MTX 60) adjusts the spectral characteristics of the film F so that the obtained output image (information) is finished in an appropriate color. Photosensitive material (photographic paper)
A matrix operation set in accordance with the spectral characteristics of the image data, the characteristics of the development processing, and the like is performed to perform saturation correction.

The image information processed by the first MTX 76 is
An adder 86 (adder 72) and a second MTX 78 (2M) for generating image data for performing dodging processing
TX62). When the dodging process is not performed, the first MTX 76 and a third LUT 84 described later are used.
(The first MTX 60 and the third LUT 68) are connected by bypass, and image information for dodging processing is not generated. The presence or absence of these processes may be determined by a mode selection based on an operator's input, a method of judging from a calculation result in the condition setting unit 44, or the like.

The second MTX 78 (second MTX 62) generates bright / dark image data of the read image from the R, G, and B image data sent from the first MTX 76. Examples of the method of generating bright and dark image data include a method of taking one-third of the average value of the R, G, and B image data, and a method of converting color image data into bright and dark image data using the YIQ rule. . As a method of obtaining bright and dark image data using the YIQ rule, for example, a method of calculating only the Y component of the YIQ rule from the R, G, and B image data by the following equation is exemplified. Y = 0.3R + 0.59G + 0.11B

The LPF 80 (LPF 64) is a second MTX
The light and dark image data generated in 78 is processed by the LPF,
By extracting the low-frequency component, the light and dark image is two-dimensionally blurred to obtain blurred image data of the read image. As the LPF used for the LPF 80,
FIR (Finite Impulse) commonly used for blurred image generation
A Respones (LP) type LPF may be used, but an IIR (Infinite Impulse Responses) type LPF is preferably used because blurred image data in which a large image is blurred can be generated by a small circuit. Further, a median filter (MF) may be used instead of the LPF 80. Use of the MF is preferable in that blurred image data in which noise (high-frequency components) in a flat portion is cut can be obtained while preserving edges. In addition, it is particularly advantageous to use the MF and the LPF together and to weight and add the images obtained by using the MF and the LPF in that the blurred image data in which the image is largely blurred can be generated while taking advantage of the advantage of the MF. preferable.

Here, as described above, since the resolution of the image is different between the pre-scan image data and the main scan image data, if the processing is performed using the same LPF, the image displayed on the display 20 and the print will not be printed. The reproduced image will be different. Therefore, it is necessary to change the frequency characteristics of the LPF 64 for processing the pre-scan image data and the LPF 80 for processing the main scan image data according to the resolution. Specifically, the blur amount of the blurred image data used for the display on the display 20 may be reduced by the resolution ratio, and the resolution ratio is set to m, LP
Assuming that the cutoff frequency of F64 is fc (p) and the cutoff frequency of LPF 80 is fc (f), the LPF may be designed so that fc (p) (mfc (f).

The blurred image data generated by the LPF 64 is sent to the second LUT 82 (second LUT 66) and processed by the dynamic range compression table.

The density range of an image that can be photographed on the film F is generally wider than the reproduction range in printing. For example, in a backlight scene or flash photography, the density range (minimum density) greatly exceeds the reproduction range of printing. In some cases, an image having a difference between the maximum density and the maximum density (dynamic range) is captured. In this case, the entire image data (pixels) cannot be reproduced on the print, and the high-density portion of the film (reading signal intensity is weak) exceeding the reproduction range, that is, the bright portion of the subject jumps white on the print, and conversely. The low-density portion of the film exceeding the reproduction range, that is, the dark portion of the subject is blackened on the print. Therefore, in order to obtain an image in which all the image data is reproduced, it is necessary to compress the dynamic range of the image data to correspond to the reproduction range of the print. In other words, the image data is adjusted so that the dynamic range is compressed by adjusting the density of the light and dark areas without changing the gradation of the intermediate density area so as to provide the same effect as dodging by conventional direct exposure. Must be processed (dodging).

In the illustrated processing apparatus 10, the first MTX7
The second LUT is added to the main image data processed in step 6.
By adding the blurred image data processed by the dynamic range compression table 82, the dynamic range of the image data is non-linearly compressed to perform a dodging process, and the dynamic range and bright /
It is assumed that the gradation and the density of the dark portion are appropriate, and the image data is output image data which gives the same impression as when the person views the original scene (shooting scene) and which can obtain a print in which a high-quality image is reproduced. That is, the dynamic range compression table of the second LUT 82 is a table for performing image processing of the blurred image data and obtaining processing image data for appropriately compressing the dynamic range and the like of main image data.

The dynamic range compression table (hereinafter, referred to as a compression table) is also created by the setup unit 50. Here, in the conventional apparatus, the compression table is created using only the pre-scan data, but in the present invention, the compression table is created with reference to the shooting information in addition to the pre-scan data. In the present invention, by having such a configuration, it is possible to more stably output a high-quality image (image data) which gives the same impression as when a person views an original scene (shooting scene). Making it possible.

In the illustrated example, this compression table is
It is created as follows. First, an overall (dynamic range) compression rate α is calculated, and a compression function f (α) using this is set. For example, a function as shown in FIG. 5 is set in the setup unit 50, and the dynamic range (D
R), the compression ratio α is calculated. In this function, when the dynamic range is smaller than the threshold DRth, the compression ratio α is 0, and in the case of an image having a small dynamic range, the compression processing of the dynamic range is not performed. This is because, when compression processing is performed on an image having a small dynamic range, the contrast of the image is reduced, and conversely, the image quality is reduced. Further, according to the study of the present inventors, it is better to skip the image of the brightest spot like a light such as an electric light existing in the image to the lowest density on the print than to output the gradation by the dynamic range compression processing. It has been found that images can be obtained. Therefore, in the function shown in FIG. 5, even if the dynamic range is larger than the threshold DRmax, the compression rate α
Is set so as not to become smaller than the lower limit value αmax.

Using the compression ratio α, an overall compression function f (α) is created. This compression function f (α) is calculated as shown in FIG.
As shown in (a), the signal is a simple decreasing function in which the slope is the compression ratio α with a certain signal value as the intersection with the reference value Y _0, that is, the horizontal axis (output 0). The reference value Y ₀ is a reference density, and may be set as appropriate according to the density at the center of an image of a main subject or the like. For example, when a person is the main subject, a print density that is substantially the same as the skin color is 0.5%.
０．７0.7 is exemplified, and preferably about 0.6.

Further, the setup section 50 has a bright section
(Dynamic range) Compression rate α_{li ght}, And in the dark
(Dynamic range) Compression rate α_darkAnd set
Compression function f_light(α_light) And compression
Number f_dark(Α_dark). Bright part compression function f
_light(α_light) Is, as shown in FIG.
The reference value Y₀From the horizontal axis (output 0) on the brighter side
Is also a decreasing function that goes downward (minus side),
Compression rate α of bright part_lightThe reference value Y ₀
The output on the darker side is 0. This compression ratio α
_lightAre image features such as density histograms and highlights
Bright part image obtained by dodging according to the amount
Make sure that the data is the image data for the image reproduction area of the print.
Is set to On the other hand, the compression function f_dark(Α_dark)
Is the reference value Y as shown in FIG.₀Than
A decreasing function above the horizontal axis on the dark side, and a straight line
The inclination of the part is the compression ratio α of the dark part_darkFunction
Value Y₀The output on the brighter side is 0. This compression ratio α
_darkSimilarly, images such as density histograms and shadows
Depending on the feature amount, the image data in the dark area is
The setting is made so as to be the image data of the current area.

Here, in the present invention, the compression ratio α _light of the bright portion and the compression ratio α _dark of the _dark portion are not set only from the pre-scan data, but as described above, the condition setting portion 44 (setup The setting is made in consideration of the photographing information acquired by the section 50).

For example, in the case where information of strobe emission and large photographic magnification (more than a predetermined value) is obtained as photographic information,
This image can be determined to be a scene shot by flash at a short distance (close-up flash scene). In this case, it is better to perform the dodging process by largely compressing the dark part after performing the brightness correction to increase the density, and obtain an image that gives an impression closer to that when a person looks at the shooting scene. Therefore, the compression ratio α _dark of the dark part of the dodging process is set larger than usual.
If information without flash emission is obtained as shooting information, and the image data has high brightness in the highlight portion and the histogram has two peaks, this image is a scene shot in backlight (backlit scene). Scene)
The mountain on the bright side corresponds to the background, and the mountain on the dark side corresponds to the main part (for example, a person). In this case, it is similarly preferable to perform the dodging process by largely compressing the bright portion after performing the brightness correction for decreasing the density, and thus the compression ratio α _light of the bright portion in the dodging process is similarly preferable. Is larger than usual.

In the new photographic system, a shooting scene (scene ID) can be magnetically recorded on the film F. By using this, for example, when the “night scene portrait” of the shooting scene (scene ID) is acquired as the shooting information, after performing the brightness correction to increase the density, the compression ratio of the dark part of the dodging process _Make α _dark larger than usual.
Alternatively, when “snow” is similarly acquired as the photographing information, the compression ratio α _light of the bright part of the dodging process is set to be larger than usual.

As described above, the compression of the bright portion according to the photographing information
Rate α_lightAnd compression ratio α of dark area_{da rk}The setting method of
There is no limitation, for example, it is possible to determine using photographing information
Depending on the scene, the compression ratio α_lightAnd compression ratio α_darkCorrect
Correction factor to be set in advance by experiment or simulation.
Correction coefficient according to the determined scene
Read out the prescan data using this correction coefficient.
Compression rate α calculated from _lightAnd compression ratio α_darkCorrect
I just need. Alternatively, close-up strobe scenes or shooting scenes
In the case of snow, etc., the compression ratio is corrected and a compression table is created.
It is better to use a dedicated compression table than to
In many cases, experimentation and simulation
Create and store a dedicated compression table for each scene
The dedicated compression table according to the determined scene.
This may be used.

The shooting information includes a shooting scene (scene I
D), the presence / absence of strobe light emission at the time of photographing, photographing magnification, main subject position, photographer intention information, photographer preference information, and the like. At the time of photographing, the finish may be predicted while looking through the viewfinder, and ON / OFF of highlight-side compression and shadow-side compression may be input as photographer intention information. Alternatively, similar on / off may be input according to the photographer's preference.

The means for acquiring the photographing information is not particularly limited, and various methods can be used. For example,
In the case of the film F of the new photographic system, information such as the presence / absence of strobe light emission, photographing magnification, main subject position, photographing date and time, and photographing scene (scene ID) can be magnetically recorded. Can be obtained. Alternatively, function keys (for example, F1 “Night view portrait”, F2
"Snow" etc.), and display 2 at the time of certification etc.
The operator determines the scene from the image displayed at 0,
By inputting this with the keyboard 18a, the condition setting unit 44 (setup unit 50) acquires information on this scene as shooting information, and adjusts or resets the dodging process conditions set from the prescan data. May be. Further, if the image file is an image file of an image taken by a digital camera, a digital video camera, or the like instead of the scanner 12, various kinds of shooting information are recorded in the header of the image file. Alternatively, if the film is shot by a camera connectable to a personal computer, shooting information may be acquired from the camera.

Thus, the overall compression function f
(Α), compression function f of the bright part_light(α_{li ght}) ,and
Compression function f_dark(Α_dark), And the following equation
As shown in FIG._total
(Α) is created and this compression function f _totalUsing (α)
Thus, a compression table of the second LUT 82 is created. f_total(Α) = f (α) + f_light(α_light) + F
_dark(Α_darkAlternatively, as mentioned above, the compression table corresponding to the scene
If stored, compression according to the determined scene
Read the table. Compression table, parameter integration
To the second L
The UT 82 (66) is set.

According to the method of creating the compression table, the dynamic range compression changes the gradation of the intermediate density portion by fixing the reference value Y ₀ and independently setting the compression ratio of the bright portion and the dark portion. Without giving, the dynamic range compression can be performed by adjusting only the bright part and the dark part. In addition, since the change in brightness of the entire image due to the dynamic range compression can be prevented, the first LUT 74 described above is used.
Can be made independent, and setting of image processing conditions can be facilitated.

When the compression function f _light (α _light ) and the compression function f _dark (α _dark ) become functions as shown in FIGS. 6D and _6E , the point P 6 and (g), an artifact appears due to discontinuity of γ at the point Q. As shown in FIGS. 6B and 6C, the artifact appears as a function that makes the differential coefficient smooth. It is preferable not to do so.
This point is described in detail in JP-A-3-222577.

[0053] set the overall compression ratio of the compression table (compression function) alpha, compression ratio alpha _{ligh t} of the bright portion, and a dark portion of the compression ratio alpha _dark is the aforementioned adjustment key 56 gradation (gamma) key,
Light adjustment key (α light) and dark adjustment key (α
dark), for example, when these keys are pressed by an operator's verification, the corresponding adjustment amount is calculated by the key correction unit 52, and the second
The compression table set in the LUT 82 (66) is adjusted.

In the above description, the compression table for creating the image data for compressing the image is set in the second LUT 82. However, when the image photographed on the film F is under / overexposed, In order to correct this, the gradation of the dark part is set in the case of underexposure, and the gradation of the bright part is set in the case of overexposure. Preferably, the range is extended. Therefore, in this case, a dynamic range expansion table for creating image data for performing a process of expanding image data may be set in the second LUT 82. This point is described in detail in the specification of Japanese Patent Application No. 8-157200 by the present applicant.

The blurred image data processed by the second LUT 82 is sent to the adder 86 (adder 72). The adder 86 adds the main image data processed by the first MTX 76 and sent directly to the adder 86 with the blurred image data (bright and dark image data). Thus, dodging processing for compressing the dynamic range of the main image data is performed.

More specifically, the blurred image data processed by the compression table is, as is apparent from FIG. 6, image data in which a bright portion is minus and a dark portion is plus. Therefore,
By adding the blurred image data to the main image data processed by the first MTX 76, the bright part of the main image data is small and the dark part is raised, that is, the dynamic range of the image data is compressed. In addition, the pass band of the second LUT 82 corresponds to a large area contrast, and the local contrast is a higher frequency component than the pass band of the second LUT 82.
The blurred image data that has passed through the UT 82 is not compressed.
Therefore, the image obtained by the addition by the adder 86 is a high-quality image in which the dynamic range is compressed while maintaining the local contrast.

The third LUT 84 (third LUT 68) is a gradation conversion table for converting the image data obtained by the addition by the adder 86 into output image data according to the characteristics of the final output medium. That is, the third LUT 68 converts the pre-scan data into image data corresponding to the display on the display 20 using the 3D-LUT, for example.
The UT 84 similarly performs a gradation conversion on the main scan image data by the 3D-LUT so that the main scan image data becomes image data suitably corresponding to the color development of the photosensitive material Z.

As described above, the pre-scan data output from the third LUT 68 is converted into a signal corresponding to the display 20 by the signal converter 70.
The data is D / A converted by the D / A converter 88 and displayed on the display 20. Here, the image displayed on the display 20 and the print image transmitted to and reproduced by the printer 16 have been subjected to similar image processing as various image processing and dodging processing. The display 20 displays an image similar to the print image.

The operator looks at the image displayed on the display 20 to make a test, and if necessary, presses each of the adjustment keys 56 as described above to adjust the image. The key input of the adjustment key 56 by the operator is sent to the key correction unit 52 to be a correction amount of the image processing condition, and the parameter integration unit 21 integrates the correction amount and the image processing condition set by the setup unit 50. Then, new image processing conditions after key correction are set, or the image processing conditions set by the parameter integration unit 21 for both image processing units are adjusted according to the correction amount. That is,
Each correction table of the first LUT 74 (58) described above,
Compression table of LUT 82 (66) and third LU
The gradation conversion table in T84 (68) is adjusted by key input using the adjustment key 56, and accordingly,
The image displayed on the display 20 also changes.

On the other hand, the third L of the main scan image processing unit 18
After the processing in the UT 84 is completed, the main scan image data which is image data corresponding to the print image recording is
The image data is sent to the printer 16 as image data for output.

Hereinafter, the operation of the processing device 14 will be described, and the image processing device of the present invention will be described in more detail.

When the pre-scan data is stored in the pre-scan memory 40, the set-up unit 50 in the condition setting unit 44 reads out the pre-scan data, creates a density histogram, and calculates image features such as highlights and shadows. In parallel with this, the reading conditions of the main scan, such as the determination of the aperture value of the variable aperture 24, are set, and the scanner 12 is adjusted. Then, the scanner 12 performs the main scan, and the main scan data is sequentially converted to the main scan. The data is transferred and stored in the memory 40. In the processing device 14, the condition setting unit 44 includes
The information (instruction) by the key input by the operator and the magnetic information read from the film F by the carrier 30 are sent, and the condition setting unit 44 acquires the photographing information from the information.

On the other hand, the setup section 5 of the condition setting section 44
0 is a gray balance adjustment table of the first LUTs 74 and 58, a brightness correction table and a gradation correction table, a compression table of the second LUTs 82 and 66, using the created density histogram, the calculated image feature amount, and the like.
The tone conversion tables of the third LUTs 84 and 88 are created, that is, image processing conditions are set, and output to the parameter integration unit 54. Here, as described above, the compression tables of the second LUTs 82 and 66 are set in consideration of not only the pre-scan data but also the acquired shooting information. The parameter integration unit 54 transfers and sets the transmitted image processing conditions to the corresponding parts of the display image processing unit 46 and the main scan image processing unit 48.

When the image processing conditions are set, the first LUT 58 of the display image processing unit 46 reads out the pre-scan data from the pre-scan memory 40, performs processing according to the set tables, and then performs color correction with the first MTX 60. Will be applied. The image data processed by the first MTX 60 is sent to the adder 72 and the second MTX 62. Second
The MTX 62 generates bright and dark image data of an image read from the sent image data.
The image data is converted into blurred image data by the PF 64,
The data is processed by the compression table in the LUT 66 and sent to the adder 72 as blurred image data for dodging processing.
The adder 72 adds the main image data processed by the first MTX 60 and the blurred image data, compresses the dynamic range of the main image data, and generates image data for display on the display 20.

The image data output from the adder 72 is
The color is converted in the third LUT 68 so as to form an image corresponding to the display on the display 20, converted into a signal in accordance with the display on the display 20 by the signal converter 70, converted into an analog signal in the D / A converter 88, and displayed. 20 is displayed.

The operator looks at the image displayed on the display 20 to perform verification, and if necessary, adjusts the adjustment key 56.
Various adjustments are made using. When there is an input from the adjustment key 56, the correction amount of the image processing condition is calculated by the key correction unit 52, and the correction amount and the image processing condition set by the setup unit 50 are integrated by the parameter integration unit 54, The image processing conditions are reset or changed, and the LUs of the display image processing unit 46 and the main scan image processing unit 48 are changed.
The table set in T is changed accordingly, and the image on the display 20 changes. At the time of this verification, the operator may determine the scene from the image and input the scene using the function keys of the keyboard 18a, and the compression tables of the second LUTs 82 and 66 may be adjusted accordingly. Is as described above.

When the operator determines that the image is proper (test OK), an instruction for output (for example, printing start) is issued, whereby the image processing conditions are determined, and the first LUT 74 of the main scan image processing unit 48 is turned on. The main scan image data is read from the main scan memory 42.

Hereinafter, similarly to the above-described pre-scan data, the main scan image data is subjected to gray balance adjustment, brightness correction, and gradation correction by the respective tables set in the first LUT 74, and then to the first MTX 76 The correction is performed and sent to the adder 86 and the second MTX 78. The second MTX 78 generates bright and dark image data from the sent image data, and the bright and dark image data is
0 is regarded as blurred image data, and the second LUT
At 82, the data is processed by the compression table and sent to the adder 86 as blurred image data for dodging processing. In the adder 86, the main image data processed by the first MTX 76 and the blurred image data are added, the dynamic range of the main image data is compressed, and the third LUT is further added.
The tone is converted in 84 and sent to the printer 16 as output image data corresponding to the image recording.

It should be noted that the verification by the operator is not necessarily performed, and the print may be created without the verification. In this case, for example, the setup unit 50 sets the image processing conditions and the parameter integration unit 5
4 is set in each LUT, the image processing conditions are determined,
The first LUT 74 starts reading main scan image data, and performs image processing. It is preferable that the presence or absence of the test can be selected as a work mode.

As described above, the image data processed by the processing device 14 is sent to the printer 16. Printer 16
Is to expose a photosensitive material (photographic paper) in accordance with image data to record a latent image, perform development processing in accordance with the photosensitive material, and output as a (finished) print. For example, after a photosensitive material is cut into a predetermined length corresponding to a print, three types of light beams, R exposure, G exposure, and B exposure, according to the back print recording and the spectral sensitivity characteristics of the photosensitive material (photographic paper) are applied. The light is modulated in accordance with image data (recorded image), deflected in the main scanning direction, and a latent image is recorded by transporting a photosensitive material in a sub-scanning direction orthogonal to the main scanning direction. The material is subjected to a predetermined wet development process such as color development, bleach-fixing, and washing with water, and after drying to produce a print,
Sort and accumulate.

The image processing apparatus of the present invention has been described in detail above. However, the present invention is not limited to the above-described example, and various modifications and changes can be made without departing from the gist of the present invention. Of course it is good.

[0072]

As described above, according to the image processing apparatus of the present invention, the scene type, luminance,
Optimum image processing conditions can be set according to the state of light rays at the time of shooting, etc., and image dynamic range compression processing (dodging processing) can be performed. It is possible to stably create a high-quality print that reproduces an image close to the impression when the image is displayed.

[Brief description of the drawings]

FIG. 1 is a block diagram of a digital photo printer using an example of an image processing apparatus of the present invention.

FIG. 2 is a block diagram of an image processing apparatus of the digital photo printer shown in FIG.

FIG. 3 is a conceptual diagram illustrating an example of an adjustment key connected to the image processing apparatus illustrated in FIG. 1;

FIG. 4 is a diagram illustrating L set in the image processing apparatus shown in FIG. 1;
In the UT, (a) shows the gray balance adjustment LUT, (b)
Indicates a brightness correction LUT, and (c) indicates a gradation correction LUT.

5 is a graph showing a function of the overall compression ratio of the dodging process in the image processing apparatus shown in FIG. 1;

FIGS. 6A, 6B, 6C, 6D, and 6E show examples of compression functions used in the image processing apparatus shown in FIG.

[Explanation of symbols]

 Reference Signs List 10 (Digital) photo printer 12 Scanner 14 (Image) processing device 16 Printer 18 Operation system 18a Keyboard 18b Mouse 20 Display 22 Light source 24 Variable aperture 26 Color filter plate 28 Diffusion box 32 Imaging lens unit 34 CCD sensor 36 Amplifier 38 Data processing Unit 40 Pre-scan (frame) memory 42 Main scan (frame) memory 44 Condition setting unit 46 Display image processing unit 48 Main scan image processing unit 50 Setup unit 52 Key correction unit 54 Parameter integration unit 56 Adjustment keys 58, 74 First LUT 60 , 76 First MTX 62, 78 Second MTX 64, 80 LPF 66, 82 Second LUT 68, 84 Third LUT 70 Signal converter 72, 86 Adder 88 D / A converter

Claims (2)

[Claims] 1. An image processing apparatus which performs predetermined image processing on image data of an image obtained by photographing to obtain image data for output, comprising: means for acquiring photographing information of the image; Setting means for setting a compression condition of the dynamic range of the image from the photographing information obtained by the obtaining means; and performing compression processing of the dynamic range of the image according to the compression condition of the dynamic range set by the setting means. An image processing apparatus comprising: processing means. 2. The image processing apparatus according to claim 1, wherein the setting unit sets a compression condition of a dynamic range using an image feature amount calculated from the image data.