JP2005020061A - Video signal processing apparatus and video signal processing method - Google Patents

Abstract

There is provided a video signal processing apparatus capable of obtaining a good video signal in which a contour portion of an image is kept sharp even when the image is enlarged.
An image signal processing apparatus includes an imaging unit that images a subject, an image enlargement rate determining unit that determines an enlargement rate for enlarging an image captured by the imaging unit, and the image enlargement rate. An image enlarging unit 14 for enlarging an image captured by the imaging unit 11 at an enlarging rate determined by the determining unit 17, and contour correction for the video signal of the image expanded by the image enlarging unit 14. Camera signal processing means 18 for performing camera signal processing including the luminance signal and the color difference signal, and contour correction gain in the camera signal processing means 18 as the enlargement ratio determined by the image enlargement ratio determination means 17 increases. And a contour correction gain adjusting means 19 for adjusting so as to increase.
[Selection] Figure 1

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a video signal processing apparatus and a video signal processing method suitable for use in an imaging apparatus such as a video camera.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a video signal processing device used in an imaging device such as a video camera is equipped with an electronic zoom function for electrically enlarging an image captured by an imaging element such as a CCD (Charge Coupled Device) by image processing. There is something to do. Focus (focal point) control in the electronic zoom function is mainly performed by detecting the sharpness of the screen and adjusting the focus by controlling the lens position so as to maximize it. As the sharpness evaluation value, the level (focus voltage) of the high frequency component of the video signal extracted by a band pass filter in a certain band is generally used. As shown in FIG. 4, when a normal subject is imaged, the level of the high-frequency component increases as the focus is achieved, and the point where the level is maximum is set as the in-focus position.
[0003]
In addition, the focus evaluation value capture range is not only fixed near the center of the screen, but also when the electronic zoom is used, the focus evaluation value capture range is adjusted in conjunction with the electronic zoom area so that appropriate focus control is possible even during electronic zoom. (For example, refer to Patent Document 1).
[0004]
[Patent Document 1]
JP-A-9-46571 (page 4, page 5, FIG. 6)
[0005]
[Problems to be solved by the invention]
However, in the conventional video signal processing apparatus, although the focus is appropriately adjusted following the electronic zoom, the contour (edge) portion of the image is enlarged by the electronic zoom, so that the sharpness of the contour portion of the image is impaired. There is a problem that it will be. This problem becomes more pronounced as the zoom magnification increases. There is also a problem that the sharpness of the contour portion of the image tends to decrease as the subject is located farther away.
[0006]
The present invention has been made in view of the above points, and a video signal processing apparatus and a video signal processing capable of obtaining a good video signal in which a contour portion of an image is kept sharp even in an image after electronic zooming It aims to provide a method.
[0007]
[Means for Solving the Problems]
The video signal processing apparatus according to the first aspect of the present invention is an image pickup means for picking up a subject, an image enlargement ratio determining means for determining an enlargement ratio for enlarging an image picked up by the image pickup means, and the image enlargement ratio determination. Image enlarging means for enlarging an image captured by the imaging means at an enlargement ratio determined by the means, and camera signal processing including contour correction for the video signal of the image enlarged by the image enlarging means And a camera signal processing means for generating a luminance signal and a color difference signal, and a contour for adjusting the contour correction gain in the camera signal processing means to increase as the magnification ratio determined by the image magnification ratio determination means increases. Correction gain adjusting means.
[0008]
According to this configuration, since the contour correction gain in the camera signal processing means is adjusted according to the magnification ratio of the image, it is possible to obtain a good video signal in which the contour portion of the image is kept sharp even when the image is magnified. Can do.
[0009]
According to a second aspect of the present invention, there is provided a video signal processing apparatus, an image pickup device that picks up an image of a subject, a lens that collects light on the image pickup device, an image enlargement unit that enlarges an image picked up by the image pickup device, and the image Camera signal processing means for generating a luminance signal and a color difference signal by performing camera signal processing including contour correction on the video signal of the image enlarged by the enlargement means, and contour correction generated by the camera signal processing means A focus evaluation value that is used as a reference for focus control is calculated based on a later luminance signal, a focus adjustment unit that adjusts the focus by controlling the position of the lens based on the calculated focus evaluation value, and the focus adjustment unit. Distance calculating means for calculating the distance to the subject based on the focus evaluation value calculated in the above, the F value indicating the brightness of the lens, and the size of the image sensor; and The distance to the subject calculated by the calculating means is characterized by comprising a contour correction gain adjustment means for adjusting to the contour correction gain becomes larger in the camera signal processing means with increasing distance.
[0010]
According to this configuration, the distance to the subject is calculated, and the contour correction gain in the camera signal processing means is adjusted according to the distance, so that the contour portion of the image can be obtained even when shooting a far subject. A good video signal that is kept sharp can be obtained.
[0011]
According to a third aspect of the present invention, there is provided a video signal processing apparatus, an image pickup device for picking up an image of a subject, a lens for collecting light on the image pickup device, and an image enlargement for determining an enlargement ratio for expanding an image picked up by the image pickup device A rate determining means, an image enlarging means for enlarging an image captured by the image sensor at an enlargement ratio determined by the image enlargement ratio determining means, and a video signal of an image enlarged by the image enlarging means A camera signal processing unit that performs camera signal processing including contour correction to generate a luminance signal and a color difference signal, and a focus control reference based on the luminance signal after contour correction generated by the camera signal processing unit. A focus adjustment value for calculating a focus evaluation value, adjusting a focus by controlling the position of the lens based on the calculated focus evaluation value, and a focus calculated by the focus adjustment means A distance calculation unit that calculates a distance to the subject based on an F value that indicates the value and the brightness of the lens, and the size of the imaging device, and the magnification rate determined by the image magnification rate determination unit is high. The contour correction gain in the camera signal processing means is adjusted so as to increase, and the contour correction gain in the camera signal processing means increases as the distance to the subject calculated by the distance calculation means increases. And a contour correction gain adjusting means for adjusting to the above.
[0012]
According to this configuration, since the contour correction gain is adjusted according to the magnification ratio of the image and the distance to the subject, the contour of the image can be obtained even when the image is magnified or when a far subject is photographed. It is possible to obtain a good video signal with the portion kept sharp.
[0013]
According to a fourth aspect of the present invention, there is provided an image processing apparatus comprising the video signal processing apparatus according to any one of the first to third aspects, and a predetermined image based on the video signal from the video signal processing apparatus. It is characterized by performing processing.
[0014]
According to this configuration, even when an image is magnified or when a distant subject is photographed, the contour portion of the image can be kept sharp and high-precision image processing can be performed.
[0015]
A video signal processing method according to a fifth aspect of the present invention is a video signal processing method for generating a luminance signal and a color difference signal by performing camera signal processing including contour correction on a video signal of an image enlarged after imaging. The contour correction amount is increased as the image enlargement ratio increases.
[0016]
According to this method, since the contour correction amount is adjusted in accordance with the magnification ratio of the image, it is possible to obtain a good video signal in which the contour portion of the image is kept sharp even when the image is magnified.
[0017]
A video signal processing method according to a sixth aspect of the invention is a video signal processing method for generating a luminance signal and a color difference signal by performing camera signal processing including contour correction on a video signal of an image enlarged after imaging. The contour correction amount is increased as the distance to the subject increases.
[0018]
According to this method, since the distance to the subject is calculated and the contour correction amount is adjusted according to the distance, the contour portion of the image is kept sharp even when shooting a far subject. Video signals can be obtained.
[0019]
A video signal processing method according to a seventh aspect of the invention is a video signal processing method for generating a luminance signal and a color difference signal by performing camera signal processing including contour correction on a video signal of an image enlarged after imaging. The contour correction amount is increased as the image enlargement ratio is increased, and the contour correction amount is increased as the distance to the subject is increased.
[0020]
According to this method, the amount of contour correction is adjusted according to the magnification ratio of the image and the distance to the subject. Therefore, even when the image is magnified or when a distant subject is photographed, the contour of the image It is possible to obtain a good video signal with the portion kept sharp.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0022]
(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a video signal processing apparatus according to Embodiment 1 of the present invention. In FIG. 1, a video signal processing apparatus 1 according to the present embodiment includes a condensing lens 10, an imaging unit (imaging unit) 11 including an imaging device such as a CCD (Charge Coupled Device), a preprocessing unit 12, and the like. , An A / D (Analog / Digital) converter 13, an electronic zoom unit (image enlargement unit) 14, a memory unit 15, an AF (Auto Focus) evaluation value control unit (focus adjustment unit) 16, and a microcomputer (micro) A computer) (image enlargement ratio determining means) 17, a camera process section (camera signal processing means) 18, and a contour correction gain adjustment section (contour correction gain adjustment means) 19.
[0023]
The imaging unit 11 converts light incident through the lens 10 into an electrical signal and outputs it as an analog video signal. The pre-processing unit 12 processes the analog video signal output from the imaging unit 11, and includes a CDS circuit (not shown) that removes reset noise of the analog video signal, and an analog video signal from which the noise component has been removed. An AGC circuit (not shown) that adjusts the amplitude so as to maintain a constant signal level, and a clamp circuit (not shown) that clamps the analog video signal whose amplitude is adjusted to perform digital conversion are provided.
[0024]
The A / D converter 13 converts the output of the preprocessing unit 12 into a digital signal. The electronic zoom unit 14 performs electronic zoom processing on the video signal after digital conversion. In other words, the image picked up by the image pickup unit 11 is electrically enlarged by performing image processing. In this case, the image is enlarged to a size corresponding to the electronic zoom magnification. The memory unit 15 stores the digital video signal digitally converted by the A / D converter 13. The AF evaluation value control unit 16 calculates a focus evaluation value used as a reference for focus control based on the brightness signal after the contour correction generated by the camera process unit 18, and controls the position of the lens 10 to adjust the focus. . The camera process unit 18 performs camera signal processing such as contour correction, gamma correction, luminance signal processing, and color difference signal processing on the video signal obtained through the electronic zoom unit 14 to obtain a final luminance signal (Yout). A color difference signal (Cout) is generated.
[0025]
The microcomputer 17 includes a CPU (not shown), a program memory storing a program for controlling the CPU, and a work memory used for the operation of the CPU. The electronic zoom unit 14, the memory unit 15, and AF evaluation Each of the value control unit 16, the camera process unit 18, and the contour correction gain adjustment unit 19 is controlled. When performing the electronic zoom process, the microcomputer 17 sets the electronic zoom magnification of the electronic zoom unit 14 and inputs zoom magnification information corresponding to the electronic zoom magnification to the contour correction gain adjustment unit 19. The contour correction gain adjustment unit 19 adjusts the contour correction gain in the contour correction processing in the camera process unit 18 based on the zoom magnification information input from the microcomputer 17. Here, the contour correction gain is adjusted to be larger as the electronic zoom magnification is higher. For example, when the image is magnified twice with the electronic zoom, the contour correction gain is adjusted to be twice that when the image is not zoomed.
[0026]
In the video signal processing apparatus 1 having such a configuration, when the electronic zoom process is performed, the microcomputer 17 gives an instruction including an image enlargement and an enlargement ratio to the electronic zoom unit 14. When there is an image enlargement instruction from the microcomputer 17, the electronic zoom unit 14 performs electronic zoom processing on the digital video signal from the A / D converter 13. At the same time, the microcomputer 17 gives zoom magnification information (information indicating the enlargement ratio given to the electronic zoom unit 14) to the contour correction gain adjustment unit 19.
[0027]
The contour correction gain adjustment unit 19 adjusts the contour correction gain in the camera process unit 18 based on the zoom magnification information input from the microcomputer 17. That is, if the zoom magnification in the electronic zoom unit 14 is large, the contour correction gain of the camera process unit 18 is adjusted to be high, and if the zoom magnification in the electronic zoom unit 14 is small, the gain is adjusted to be low. By this adjustment, the contour correction amount in the contour correction processing of the camera process unit 18 is appropriately maintained, and as a result, a video signal in which the sharpness of the contour portion of the image is kept good is output from the camera process unit 18.
[0028]
As described above, according to the video signal processing apparatus 1 of the present embodiment, the electronic zoom unit 14 electrically enlarges the image captured by the imaging unit 11 at the zoom magnification determined by the microcomputer 17, and the camera The process unit 18 performs camera signal processing including contour correction, gamma correction, luminance signal processing, and color difference signal processing on the video signal of the image enlarged by the electronic zoom unit 14 to generate a luminance signal and a color difference signal. The contour correction gain adjustment unit 19 adjusts so that the contour correction gain in the camera process unit 18 increases as the zoom magnification determined by the microcomputer 17 increases.
[0029]
Therefore, even when the sharpness of the contour portion of the image is impaired by the electronic zoom, the sharpness of the contour portion of the image can be appropriately maintained. In addition, the AF evaluation value control unit 16 that calculates the focus evaluation value can calculate the evaluation value based on an image in which the sharpness of the outline portion of the image is appropriately maintained even in an electronic zoomed image. A good video signal (luminance signal (Yout), color difference signal (Cout)) is generated from the process unit 18.
[0030]
(Embodiment 2)
FIG. 2 is a block diagram showing the configuration of the video signal processing apparatus according to Embodiment 2 of the present invention. The video signal processing apparatus 2 according to the present embodiment includes a distance calculation unit (distance calculation means) 20 in addition to the same configuration as the video signal processing apparatus 1 according to the first embodiment shown in FIG. In addition, the same number is attached | subjected with the same name about the part which is common in the video signal processing apparatus 1 of Embodiment 1. FIG.
[0031]
In FIG. 2, the distance calculation unit 20 calculates the distance to the subject based on the focus evaluation value calculated by the AF evaluation value calculation unit 16, the F value indicating the brightness of the lens 10, the image sensor size of the imaging unit 11, and the like. calculate. For example, if the size of the image sensor is 1/3 inch and the F value of the lens 10 is 0.76, the focal length is 40 mm, and the distance to the focused subject at this time is 5 m. The size information of the image sensor and the distance information from the focal length to the subject in focus are held. Thus, if the focus evaluation value is a peak, the distance to the subject can be calculated as 5 m.
[0032]
The microcomputer 17 not only controls the contour correction gain by the magnification of the electronic zoom based on the distance information to the subject, but also follows the distance to the subject and contours so that the contour correction gain increases when the distance to the subject is far. The correction gain adjustment unit 19 is controlled. As a result, the contour correction amount can be appropriately controlled following the distance even with respect to a distant image whose sharpness tends to be reduced, so that the sharpness of the contour portion of the image can be appropriately maintained. As a result, a good video signal (luminance signal (Yout), color difference signal (Cout)) is generated from the camera process unit 18.
[0033]
Thus, according to the video signal processing device 2 of the present embodiment, the distance calculation unit 20 uses the focus evaluation value calculated by the AF evaluation value control unit 16, the F value indicating the brightness of the lens 10, and the imaging unit. The distance to the subject is calculated based on the size of the 11 image sensors, and information on the calculated distance to the subject is given from the distance calculation unit 20 to the microcomputer 17, and the contour correction gain adjustment unit 19 In addition to the adjustment of the contour correction gain in the process unit 18, adjustment is performed so that the contour correction gain in the camera process unit 18 increases as the distance to the subject increases. Even in the case of shooting, it is possible to obtain a good video signal in which the contour portion of the image is kept sharp.
[0034]
(Embodiment 3)
FIG. 3 is a block diagram showing a configuration of an image processing apparatus according to Embodiment 3 of the present invention. As shown in FIG. 3, the image processing apparatus 3 according to the present embodiment includes the video signal processing apparatus 2 according to the second embodiment described above and an image processing unit 21. In addition, the same number is attached | subjected with the same name about the part which is common with the video signal processing apparatus 2 of Embodiment 2. FIG.
[0035]
In FIG. 3, an image processing unit 21 performs predetermined image processing based on the video signal from the video signal processing device 2, and is appropriate even when the subject is far away or an electronic zoomed image. Since image processing can be performed based on an image that has been adjusted in focus and the sharpness of the contours of the image is properly maintained, even if image processing such as object identification is performed, erroneous recognition Low-accuracy image processing can be performed.
[0036]
As described above, according to the image processing apparatus 3 of the present embodiment, since the video signal processing apparatus 2 of the second embodiment is provided, when an image is enlarged or a distant subject is photographed. Even in such a case, the contour portion of the image can be kept sharp and image processing with high accuracy can be performed.
[0037]
【The invention's effect】
As described above, according to the present invention, the contour correction gain is adjusted in accordance with the enlargement ratio of the image. Therefore, even when the image is enlarged, a good video signal is obtained in which the contour portion of the image is kept sharp. be able to.
[0038]
Further, according to the present invention, the distance to the subject is calculated, and the contour correction gain is adjusted according to the distance, so that the contour portion of the image is kept sharp even for a subject that exists far away. Video signals can be obtained.
[0039]
Furthermore, according to the present invention, the contour correction gain is adjusted according to the magnification ratio of the image and the distance to the subject, so that the contour of the image can be obtained even when the image is magnified or the subject is located in the distance. It is possible to obtain a good video signal with the portion kept sharp.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a video signal processing apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a block diagram showing a configuration of a video signal processing apparatus according to Embodiment 2 of the present invention.
FIG. 3 is a block diagram showing a configuration of an image processing apparatus according to Embodiment 3 of the present invention.
FIG. 4 is a diagram illustrating a relationship between a focus lens position and a focus evaluation value.
[Explanation of symbols]
1, 2 Video signal processing device 3 Image processing device 10 Lens 11 Imaging unit 12 Pre-processing unit 13 A / D converter 14 Electronic zoom unit 15 Memory unit 16 AF evaluation value control unit 17 Microcomputer 18 Camera process unit 19 Contour correction gain adjustment Unit 20 Distance calculation unit 21 Image processing unit

Claims (7)

Imaging means for imaging a subject;
An image enlargement ratio determining means for determining an enlargement ratio for enlarging an image captured by the imaging means;
An image enlarging means for enlarging an image captured by the imaging means at an enlargement ratio determined by the image enlargement ratio determining means;
Camera signal processing means for performing camera signal processing including contour correction on the video signal of the image enlarged by the image enlargement means to generate a luminance signal and a color difference signal;
And a contour correction gain adjusting unit that adjusts the contour correction gain in the camera signal processing unit to increase as the magnification determined by the image magnification determination unit increases. Processing equipment. An image sensor for imaging a subject;
A lens that collects light on the imaging device;
Image enlarging means for enlarging an image captured by the image sensor;
Camera signal processing means for performing camera signal processing including contour correction on the video signal of the image enlarged by the image enlargement means to generate a luminance signal and a color difference signal;
A focus evaluation value used as a reference for focus control is calculated based on the brightness signal after contour correction generated by the camera signal processing means, and the lens position is controlled based on the calculated focus evaluation value to focus. A focus adjusting means to adjust;
Distance calculation means for calculating the distance to the subject based on the focus evaluation value calculated by the focus adjustment means, the F value indicating the brightness of the lens, and the size of the image sensor;
And a contour correction gain adjusting means for adjusting the contour correction gain in the camera signal processing means to increase as the distance to the subject calculated by the distance calculating means increases. Signal processing device. An image sensor for imaging a subject;
A lens that collects light on the imaging device;
An image enlargement ratio determining means for determining an enlargement ratio for enlarging an image captured by the image sensor;
Image enlarging means for enlarging an image captured by the image sensor at an enlargement ratio determined by the image enlargement ratio determining means;
Camera signal processing means for performing camera signal processing including contour correction on the video signal of the image enlarged by the image enlargement means to generate a luminance signal and a color difference signal;
A focus evaluation value used as a reference for focus control is calculated based on the brightness signal after contour correction generated by the camera signal processing means, and the lens position is controlled based on the calculated focus evaluation value to focus. A focus adjusting means to adjust;
Distance calculation means for calculating the distance to the subject based on the focus evaluation value calculated by the focus adjustment means, the F value indicating the brightness of the lens, and the size of the image sensor;
The contour correction gain in the camera signal processing means is adjusted to increase as the enlargement ratio determined by the image enlargement ratio determination means increases, and the distance to the subject calculated by the distance calculation means is A video signal processing apparatus comprising: a contour correction gain adjusting unit that adjusts the contour correction gain in the camera signal processing unit to increase as the distance increases. An image processing apparatus comprising the video signal processing apparatus according to claim 1, wherein predetermined image processing is performed based on a video signal from the video signal processing apparatus. A video signal processing method for generating a luminance signal and a color difference signal by performing camera signal processing including contour correction on a video signal of an image magnified after imaging, and the amount of contour correction is increased as the magnification ratio of the image increases. Video signal processing method to enlarge. A video signal processing method for generating a luminance signal and a color difference signal by performing camera signal processing including contour correction on a video signal of an image magnified after imaging, wherein the contour correction amount is increased as the distance to the subject increases. A video signal processing method characterized by enlarging. A video signal processing method for generating a luminance signal and a color difference signal by performing camera signal processing including contour correction on a video signal of an image magnified after imaging, and the amount of contour correction is increased as the magnification ratio of the image increases. A video signal processing method characterized by increasing the contour correction amount as the distance to the subject increases.

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