JP4626534B2 - Image processing apparatus and method, program, and recording medium - Google Patents

Description

  The present invention relates to an image processing apparatus capable of controlling a video signal so as to improve its visibility according to an input signal and display image contents, and a method thereof.

  Conventionally, in a television receiver, a mobile display device, an in-vehicle display device, etc., for the purpose of improving the expressive power of an image according to the display content of an input signal and improving the image quality, the contrast and brightness of a video signal, Techniques for adaptively controlling display luminance, color signals, and the like of display devices have been developed.

  For example, a specific example is shown in Patent Document 1, which includes luminance feature detection means for detecting video feature information of luminance of an input video signal, and a luminance correction circuit for correcting and controlling contrast and brightness for the luminance signal. In addition, the contrast and brightness of the display image are adaptively controlled with respect to the luminance correction circuit in accordance with luminance characteristic information such as the maximum value, minimum value, and average value of the detected video signal.

On the other hand, in the example of the adaptive control for the color signal, a specific example is shown in Patent Document 2, which is based on the input RGB signal, the hue signal (H), the saturation signal (S), and the lightness signal (L). The correction intensity is calculated according to the average value of the saturation, which is the feature amount detected by the saturation histogram measurement unit and the feature amount calculation unit, and the correction coefficient calculated by the saturation enhancement coefficient calculation unit is adjusted accordingly. Then, saturation enhancement processing is performed as γ processing by the correction coefficient in the saturation correction execution unit, and the hue signal (H), the enhanced saturation signal (S ′), and the brightness signal (L) are converted into RGB signals. Convert and output.
JP 2001-027890 A JP 2001-230941 A

  However, the image display devices shown in Patent Document 1 and Patent Document 2 are all intended to improve image quality by assuming natural images such as TVs, DVDs, and camera-captured images as display objects and image processing objects. Therefore, in the case of improving the visibility for the display of so-called computer graphics images such as map images in a car navigation system, a sufficient effect can be obtained from the visual characteristics. There is no case.

  As shown in FIG. 11b, in the case of an AV natural image such as a TV as a general feature, the distribution of signal levels of a video feature for both a saturation component and a lightness component (or luminance component) is low saturation and high saturation. The frequency of intermediate levels tends to be relatively small. In addition, their signal dynamic range is often narrower than computer graphics images. On the other hand, for a computer graphics image as shown in FIG. 11a, the signal dynamic range of the saturation component and the brightness component is generally wider than that of an AV natural image, and the signal level distribution state is also an intermediate level. The frequency of this is not necessarily high.

  In general map images in car navigation systems, high-saturation colors are used for landmarks and traffic signs on the map, characters of place names, and objects that need to stand out, such as an intersection enlarged display and a direction indication display before the intersection. In many cases, a relatively low-saturation color is often used for the background color of the map portion because it is easy to see and does not get tired. Accordingly, in a map image or the like for car navigation, for example, as shown in FIG. 5a and FIG. 6, image saturation, brightness, hue, etc. for each region (area) on the screen are shown as image features. There are many images that tend to be biased, such as being concentrated closer to the same level as natural images or concentrated in an area with a high saturation color, or concentrated in another area with a low saturation color. it is conceivable that. Similarly, in the case of simultaneous display of a TV image and a map image by a multi-screen display function as shown in FIG. 5B, or simultaneous display of vehicle information and other information and a map image, the brightness and color depending on the area in the screen. It is conceivable that the degree level is biased.

  In the case of the image display devices disclosed in Patent Documents 1 and 2, none of the image display apparatuses has a correction processing configuration that individually considers the characteristics of each area in the screen. FIG. 13 is a flowchart for explaining the flow of saturation enhancement processing in consideration of the saturation feature amount in the image processing apparatus disclosed in Patent Document 2. In the case of the image processing apparatus disclosed in Patent Document 2, correction for color signals is performed by the saturation correction execution unit as γ processing, but the saturation feature information detected by the saturation histogram measurement unit and the feature amount detection unit is Saturation bias based on the average value of saturation, and as shown in FIG. 12, the saturation enhancement coefficient emphasizes the average value when the average value of saturation is at an intermediate level. When the image has a bias toward the low saturation side or the high saturation side, the operation is performed so as to suppress the saturation enhancement. However, since these processes are controlled by the averaged result on the entire screen, appropriate corrections for saturation and lightness signals are taken into account when considering each area in the screen in the case of the map image etc. It is something that cannot be applied.

  The object of the present invention is to improve the above-described problems, and so-called saturation values and brightness values tend to be biased between areas in the screen, like a map image in a car navigation system. Even in the display of computer graphics images, all areas can be appropriately and sufficiently corrected for saturation and lightness, ensuring chromaticity differences and optimally improving image quality and visibility The device is realized.

An image processing apparatus according to the present invention is an image processing apparatus for performing image adjustment in accordance with the characteristics of an input video signal including signal components of a hue signal, a saturation signal, and a brightness signal. Saturation feature information including the maximum value, minimum value, average value, and distribution state information of the saturation signal level is independently obtained for each region obtained by dividing one screen of the input image into a plurality of predetermined regions. Saturation feature detection means for detecting each of them, and a maximum value and a minimum value of the lightness signal level independently for each area obtained by dividing one screen of an image input from the lightness signal into a plurality of predetermined areas, and Intensity feature detection means for detecting brightness feature information including an average value, and the saturation signal correction processing so as to have a nonlinear gain characteristic as an output characteristic for the input independently for each predetermined region. Configure When the input saturation signal level is low saturation, the saturation level is lowered, and the input saturation signal level is higher than the low saturation or higher than the intermediate saturation. Saturation correction processing means for increasing the saturation level when the saturation level is high, and setting independent parameters for each predetermined region according to the saturation feature information and lightness feature information for each predetermined region Video adaptive control means for controlling the saturation correction processing means, and the saturation correction processing means is configured to suppress an increase gain of the saturation level of the higher saturation than the intermediate saturation. It is a feature .

The image processing method of the present invention is an image processing method for performing image adjustment according to the characteristics of an input video signal including signal components of a hue signal, a saturation signal, and a brightness signal, and the saturation signal Saturation feature information including the maximum value, the minimum value, the average value, and the distribution state information of the saturation signal level independently for each area obtained by dividing one screen of an image input from a plurality of predetermined areas Saturation feature detection processing for detecting each of the image signals, and the maximum value and the minimum value of the lightness signal level independently for each region obtained by dividing one screen of an image input from the lightness signal into a plurality of predetermined regions. And a brightness feature detection process for detecting brightness feature information including an average value, and a saturation signal correction process so as to have a nonlinear gain characteristic as an output characteristic for an input independently for each of the predetermined regions. To configure When the input saturation signal level is low saturation, the saturation level is reduced, and the input saturation signal level is higher than the low saturation or higher than the intermediate saturation. Saturation correction processing for increasing the saturation level in the case of high saturation, and setting independent parameters for each predetermined region according to the saturation feature information and lightness feature information for each predetermined region And a video adaptive control process for controlling the saturation correction process, wherein the saturation correction process is controlled to suppress an increase gain of the saturation level of the high saturation rather than the intermediate saturation. Is.

  According to the present invention, the input video signal is corrected and controlled for the purpose of improving the visibility when the illuminance state of the usage environment is very dark or bright, or for improving the image quality and improving the visibility according to the state of the image. In this case, it is possible to provide an image display apparatus that always performs optimum signal correction control regardless of the type of the input video signal, the video state, the video scene, and the like.

  In particular, like a so-called computer graphics image such as a map image display in a car navigation system and a vehicle information display in an in-vehicle display device, the dynamic range of the brightness signal and saturation signal (color signal) of the image is wide, and the signal Sufficient and optimal saturation correction can be performed even in the case of an image having a characteristic that the distribution state of levels and the distribution state in each area are biased. Thereby, by ensuring a sufficient chromaticity difference between the color signals, the visibility can be effectively improved under the adverse conditions of the illuminance environment such as extremely bright or dark.

  Hereinafter, an image display device and a display method thereof according to the present invention will be described with reference to the drawings. In the following embodiments, a liquid crystal display device will be described as an example of a display device. However, an image display device to which the present invention is applied is not limited to this example, and an organic EL (electroluminescence) display device or a PDP ( The present invention can be similarly applied to a plasma display panel) display device or the like.

(Embodiment 1)
FIG. 1 is a block diagram showing the configuration of the image display device according to the first embodiment of the present invention.

  The image display apparatus of FIG. 1 includes color space conversion means 1, lightness correction processing means 2, saturation correction processing means 3, lightness feature detection means 4, saturation feature detection means 5, saturation lightness video adaptive control means 6, color Spatial inverse transformation means 7 and a display panel 8 are provided.

  Hereinafter, the case where the display panel 8 is an in-vehicle display which is a liquid crystal display will be described.

  An input video signal in the Y color difference signal format is input to the color space conversion means 1. The luminance signal and the color difference signal are once converted into RGB signals, and then converted from the RGB signals into signal components of a hue signal, a saturation signal, and a brightness signal. In this embodiment, the signal form of the input video signal is the Y color difference signal, but an RGB signal may be used depending on the system.

  This signal conversion is performed by the following arithmetic expression.

Lightness signal V = MAX (R, G, B)
Hue signal H = {MID (R, G, B) −MIN (R, G, B)} / {MAX (R, G, B) −MIN (R, G, B)}
Saturation signal S = {MAX (R, G, B) −MIN (R, G, B)} / MAX (R, G, B)
Where MAX (R, G, B) is the maximum value of each RGB signal
MID (R, G, B) is the intermediate value of RGB signals
MIN (R, G, B) represents the minimum value among the RGB signals.

  At the time of this conversion, it is determined which of MAX, MID, and MIN each corresponds to RGB.

  After the conversion, the brightness signal is sent to the brightness correction processing means 2 and the brightness feature detection means 4, the saturation signal is sent to the saturation correction processing means 3 and the saturation feature detection means 5, and the hue signal is inverted from the color space. It is output to the conversion means 7. In the brightness correction processing unit 2, brightness brightness control and contrast gain control are performed on the brightness signal and output to the color space inverse conversion unit 7. In the saturation correction processing unit 3, saturation gain control and offset control are performed on the saturation signal and output to the color space inverse conversion unit 7. The brightness feature detection means 4 detects the maximum value, the minimum value, and the average value as video feature values of the brightness signal and outputs them to the saturation brightness video adaptive control means 6. The saturation feature detection means 5 detects information indicating the distribution state of the maximum value, minimum value, average value, or saturation level as the image feature value of the saturation signal, and outputs it to the saturation lightness image adaptive control means 6. Is done. The saturation lightness image adaptive control means 6 calculates a lightness correction parameter from the input lightness feature information and outputs it to the lightness correction processing means 2, and calculates a saturation correction parameter from the input saturation feature information and outputs the saturation. Output to the degree correction processing means 3. In the color space reverse conversion means 7, the input hue signal and the saturation signal and lightness signal after correction processing are converted into RGB signals by an operation reverse to that of the color space conversion means 1, and the display panel 8. Is output.

  In the image display apparatus configured as described above, the overall schematic operation will be described focusing on the lightness correction parameter calculation and the saturation correction parameter calculation that are adaptively controlled by the saturation lightness image adaptive control means 6.

  First, the lightness correction parameter calculation is performed. The control amount of contrast gain and brightness (offset) for improving the contrast of the lightness correction processing unit 2 is determined according to the feature information obtained by the lightness feature detection unit 4. Adaptive control (AI processing) is performed. This will be described with reference to FIGS. FIG. 9 shows an example of a bright input image as a whole. The dynamic range of the input image is expanded (contrast control) based on the video feature information of the maximum value, minimum value, and average value of the lightness of the input signal, and a predetermined range is obtained. Offset control (brightness control) is performed so as to fall within the range. If necessary, the operation of increasing the liquid crystal backlight luminance of the display panel 8 is performed so that the fluctuation of the average value level of the original input image due to these processes is offset by the dimming control. FIG. 10 shows an example of a dark input image as a whole, and processing is performed with the same concept as in FIG. 9, but in this case, brightness control and dimming control are performed in the opposite directions to those in FIG. It will be. As described above, in the video adaptive control (AI processing), the signal amplitude is enlarged and dimming control is performed at the same time according to the video characteristics of the input video signal, so that the contrast of the video is improved and black becomes blacker. White is one in which good signal processing that produces a whiter image is performed. In this embodiment, the brightness has been described as performing the image adaptation process performed on the brightness component of the natural image as being similar to the brightness component. However, the brightness control is limited to such a process. In the case of a map image or the like, it is also effective to perform adaptive control similar to saturation control described later.

  Next, the saturation correction parameter calculation will be described with reference to FIGS. First, the saturation feature detection means 5 passes the low-pass filter on the input saturation signal, and then calculates the minimum value, maximum value, and average value of the saturation signal for a predetermined detection area in one screen. Each integrated value is calculated. The saturation lightness image adaptive control means 6 simply determines the distribution state of the saturation component level from the three parameters of the average value calculated from the minimum value, the maximum value, and the integrated value, and the corresponding saturation value. Control is performed so as to calculate the degree correction amount. FIG. 2 is a diagram for explaining a concept of an example of a method for detecting a simple distribution state of saturation components. FIG. 2a is an example of a very wide dynamic range where the minimum value is close to 0 and the maximum value is close to the maximum range, but the overall saturation level is an example with many low saturation signals. In such a case, the average value is inevitably close to the minimum value. On the other hand, FIG. 2B is an example in which the overall saturation level has more signals than relatively high saturation, and in such a case, the average value is relatively close to the maximum value.

  In this way, by calculating the average value and comparing it with the maximum and minimum values (calculating which position between the maximum and minimum values), the peak level of the distribution state (peak value of appearance frequency) ) Or the distribution state can be generally detected. It should be noted that the distribution state may be detected more strictly by performing histogram detection processing for each predetermined saturation level. Then, in consideration of this distribution state, in an image where the saturation distribution is concentrated at a relatively low saturation level, even if the maximum value is large, control is performed so that saturation correction is strongly applied as a whole, and vice versa. In an image where the saturation distribution is concentrated at a relatively high saturation level, control is performed to suppress saturation correction. In this way, by controlling the correction amount in consideration of not only the maximum saturation value but also the signal level distribution state, the image has a relatively low saturation component without giving a sense of incongruity to the image. Sufficient correction can be applied, and in the case of an image having a relatively high saturation component, excessive correction can be suppressed.

  This is shown in FIG. 3, where FIG. 3 shows a value obtained by dividing (maximum saturation value−average saturation value) by the saturation maximum value on the horizontal axis, and saturation correction processing means on the vertical axis. The saturation gain value set for 3 is taken. 3 is a correction characteristic when the maximum saturation value is almost in the vicinity of the maximum range as in the example of FIG. 2. If the maximum saturation value is low, the solid line in FIG. By setting the offset as a whole as described above, it is possible to calculate an appropriate correction control amount in consideration of the maximum value and the dynamic range.

  Next, the operation of the saturation correction processing unit 3 will be described. In the saturation correction processing means 3, as described above, the saturation signal correction control is performed with the saturation correction amount set in consideration of the saturation level distribution state in the saturation lightness image adaptive control means 6. Here, a case where saturation gain control is performed as saturation correction will be described. FIG. 4 shows an example of setting gain characteristics with respect to the saturation input level. As shown in FIG. 4, by using a non-linear characteristic as the saturation gain correction characteristic, the gain is suppressed when the input saturation level is low and high, and the intermediate saturation level is mainly gain-enhanced. The characteristics are as follows. With this gain characteristic, even if the maximum saturation value is high, if the overall saturation level is concentrated at a relatively low and medium level, a large correction amount can be achieved as a whole without saturation. It can be applied to enhance the chromaticity difference between the colors of the corrected image (increase the contrast of the saturation), which greatly improves the visibility when the illuminance environment is not good. It can be effective.

  The lightness signal, the saturation signal, and the hue signal that are corrected and controlled in this way are input to the color space reverse conversion unit 7, and the color space reverse conversion unit 7 reverses the conversion formula shown in the operation description of the color space conversion unit 1. Conversion processing is performed, and operation is performed so that MAX, MID, and MIN are calculated from the hue signal, the saturation signal, and the lightness signal, and are selected and output as RGB signals. The above is the contents of the overall schematic operation.

  Next, the processing for each predetermined area in the screen, which is a feature of the present invention, will be described in detail. First, the saturation feature detection unit 5 and the brightness feature detection unit 4 perform region setting for dividing one screen into predetermined regions according to the input region setting value. After the input signal has passed through a predetermined low-pass filter, the integrated value for calculating the maximum value, minimum value, and average value for each area, or in addition to the histogram detection for each predetermined saturation level Processing is performed. For example, as in the example shown in FIG. 6, a screen is divided into a total of 12 areas of 4 blocks in the horizontal direction and 3 blocks in the vertical direction, and the above data is obtained for each area. It is sent to the means 6. Then, the saturation lightness image adaptive control means 6 performs the arithmetic processing as described in the above description of the outline operation for each area (area), and the saturation correction amount is calculated to the saturation correction processing means 3. Given this, the saturation correction processing means 3 performs saturation correction processing for each area in the screen by setting each saturation control amount in accordance with the video feature information of the area. Specifically, in a region where saturation is distributed in a low level part, control is performed to increase the correction strength for the saturation correction processing means in that region, and video visibility is improved. In a region that is highly distributed in the high saturation portion, control is performed so as to suppress the correction strength for the saturation correction processing means in that region.

  Similarly, the brightness control amount is set for each area in the screen according to the video feature information of the corresponding area, and the brightness correction process is performed. Here, if each of the correction parameters set for the saturation and lightness correction processing means has a large difference between the adjacent areas, a sense of incongruity appears near the boundary of the corrected image. Is set by adding a low-pass filter process to each correction parameter setting value.

  As described in the problem to be solved by the invention, such area-specific processing has many images in which the saturation feature and the brightness feature tend to be biased in each area in the screen in a car navigation map image or the like. Therefore, by dividing the area into several blocks and individually controlling the blocks, adaptive control for saturation and lightness can be performed more accurately. For example, since a relatively large figure or character is displayed on the display portion of the navigation function as shown in the right part of FIG. 5a, the signal level distribution state is concentrated on a specific level in this block. Even in the case of the full-screen map image display as in the example of FIG. 6, since it is a graphics image, the signal level distribution state on the entire screen becomes a natural image by the display image as shown in FIG. It may not be a general signal level distribution that is often seen, but may be a somewhat complicated distribution. However, by dividing into areas, the image features in each area tend to have their respective tendencies as in the example of FIG. 6, and thus the signal distribution state of each area as shown in FIG. 8 is relatively simple. There is a tendency to become a distributed state. Therefore, the adaptive control for a relatively simple distribution state as shown in FIG. 8 can perform more appropriate correction than the adaptive control for the distribution state over the entire screen as shown in FIG.

  In addition, in an in-vehicle display device or the like, there are cases where a navigation map image and a natural image such as a TV image are displayed on a multi-screen as shown in FIG. 5B. In this case, the difference in tendency is more prominent as shown in FIG. It is believed that there is. Therefore, in the case of a multi-screen display system, a screen area signal for identifying each display area of each screen is input to the saturation feature detection means 5 and the brightness feature detection means 4 and this screen area signal is given priority. It is assumed that an area is divided and an operation is performed so as to input an area setting value so as to subdivide the area as necessary.

  Further, as a developed form of the present embodiment, the saturation feature detecting means 5 is divided into a large number of small blocks each having one horizontal screen of 16 pixels and 8 vertical pixels. The saturation average value is obtained, and the buffering operation is performed in the memory. The saturation lightness image adaptive control means 6 reads out each buffered data, and directly calculates from each data or by a lookup table or the like. A configuration in which a high saturation gain is calculated if the average value is low and a low saturation gain is set if the average value is high, and control is performed using the optimal saturation correction amount of each small block is also considered effective. It is done.

  As described above, the saturation and lightness feature detection means divides the screen into predetermined regions, detects detailed feature information individually, and performs saturation and lightness correction processing optimally for each region. By doing so, more detailed and appropriate saturation correction processing and lightness correction processing adapted to the display contents of each area in the screen can be performed. As a result, the display with improved visibility can be performed by enlarging the chromaticity difference between the pixel data of the different color signals of the input signal image.

  The image display apparatus described in the present embodiment is provided with the color space conversion means 1 and the color space inverse conversion means 7 as shown in FIG. 1, but the hue signal, the saturation signal, and the lightness as the input video signal. When a signal divided into each component of the signal is input, or when a hue signal, a saturation signal, and a lightness signal can be input on the display panel 8, the color space conversion means 1 and the color space reverse conversion means 7 may be an image processing apparatus configured by means 2-6.

  Further, the image display apparatus described in the present embodiment may be realized by a computer that operates according to a program indicating these processing procedures.

  An image display device and a display method thereof according to the present invention are video display devices for applications in which the illuminance range of an environment to be used is expected to vary widely, such as a vehicle-mounted display, and in particular, map images and vehicles of a car navigation system. The present invention is useful when applied to a visibility improving process when displaying a so-called computer graphics image such as information display.

The block diagram which shows the structure of the image display apparatus by 1st Embodiment of this invention. FIG. 3 is a characteristic diagram for explaining an example of a saturation signal level distribution state detection method in the saturation feature detection means shown in FIG. FIG. 3 is a characteristic diagram showing a setting example of a saturation correction amount with respect to a saturation distribution state in the saturation lightness image adaptive control means shown in FIG. FIG. 3 is a characteristic diagram for explaining an example of setting gain characteristics with respect to the saturation input level in the saturation correction processing means shown in FIG. Schematic diagram explaining an example of screen display on an in-vehicle display The schematic diagram which shows an example of the image characteristic of each area | region in 1 screen in a general map image Schematic diagram showing an example of a saturation signal level distribution state peculiar to CG such as a map image Schematic diagram showing an example of a saturation signal level distribution state in each divided region Schematic diagram illustrating an example (in the case of a bright input image) of video adaptive control (lightness AI processing) in the lightness correction processing means shown in FIG. Schematic diagram illustrating an example (in the case of a dark input image) of video adaptive control (lightness AI processing) in the lightness correction processing means shown in FIG. Characteristic diagram showing a comparative example of saturation characteristics and saturation distribution states of general natural images and map images Schematic diagram showing a saturation enhancement method for saturation features in saturation correction processing in a conventional example Flowchart showing the flow of saturation correction in a conventional image display device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Color space conversion means 2 Lightness correction processing means 3 Saturation correction processing means 4 Lightness feature detection means 5 Saturation feature detection means 6 Saturation lightness image adaptive control means 7 Color space reverse conversion means 8 Display panel

Claims (6)

An image processing apparatus for performing image adjustment according to the characteristics of an input video signal including signal components of a hue signal, a saturation signal, and a brightness signal,
The maximum value, the minimum value, the average value, and the distribution state information of the saturation signal level are included independently for each region obtained by dividing one screen of an image input from the saturation signal into a plurality of predetermined regions. Saturation feature detection means for detecting saturation feature information respectively;
Lightness feature information including the maximum value, minimum value, and average value of the lightness signal level is detected independently for each region obtained by dividing one screen of an image input from the lightness signal into a plurality of predetermined regions. Brightness feature detection means to
The saturation signal is corrected so as to have a nonlinear gain characteristic as an output characteristic for the input independently for each predetermined region, and the input saturation signal level is low saturation In this case, the saturation level is decreased, and when the input saturation signal level is intermediate saturation higher than the low saturation or high saturation higher than the intermediate saturation, the saturation level is increased. Degree correction processing means,
Video adaptive control means for controlling the saturation correction processing means by setting independent parameters for each predetermined area in accordance with the saturation characteristic information and lightness characteristic information for each predetermined area,
The saturation correction processing unit is configured to suppress an increase gain of the saturation level of the high saturation than the intermediate saturation.
An image processing apparatus. Based on the distribution state information of the saturation feature information, the video adaptive control means increases the correction strength for the saturation correction processing means in the area where the saturation is largely distributed in the low level part. Control is performed to improve image visibility, and conversely, in a region where the saturation is highly distributed in the high saturation portion, control is performed to suppress the correction strength for the saturation correction processing means in that region. The image processing apparatus according to claim 1. The video adaptive control means outputs a parameter to the saturation correction processing means so that a sudden parameter change does not occur near the boundary of each area for each parameter setting value independent for each predetermined area. 2. The image display device according to claim 1, wherein low-pass filter processing is performed. An image processing method for performing image adjustment according to the characteristics of an input video signal including signal components of a hue signal, a saturation signal, and a brightness signal,
The maximum value, the minimum value, the average value, and the distribution state information of the saturation signal level are included independently for each region obtained by dividing one screen of an image input from the saturation signal into a plurality of predetermined regions. Saturation feature detection processing for detecting saturation feature information,
Lightness feature information including the maximum value, minimum value, and average value of the lightness signal level is detected independently for each region obtained by dividing one screen of an image input from the lightness signal into a plurality of predetermined regions. Brightness feature detection processing,
The saturation signal is corrected so as to have a nonlinear gain characteristic as an output characteristic for the input independently for each predetermined region, and the input saturation signal level is low saturation In this case, the saturation level is decreased, and when the input saturation signal level is intermediate saturation higher than the low saturation or high saturation higher than the intermediate saturation, the saturation level is increased. Degree correction processing,
Video adaptive control processing for controlling the saturation correction processing by setting independent parameters for each predetermined region according to the saturation feature information and lightness feature information for each predetermined region,
The image processing method according to claim 1, wherein the saturation correction processing is controlled so as to suppress an increase gain of a saturation level of the higher saturation than the intermediate saturation . Independently for each area obtained by dividing one screen of an image input from the saturation signal of the input video signal including each signal component of the hue signal, the saturation signal, and the brightness signal into a plurality of predetermined areas, Saturation feature detection processing for detecting saturation feature information including the maximum value, minimum value, average value, and distribution state information of the saturation signal level, and a plurality of predetermined areas within one screen of an image input from the brightness signal Brightness feature detection processing for detecting brightness feature information including the maximum value, the minimum value, and the average value of the brightness signal level independently for each of the divided areas, and independently for each of the predetermined areas The saturation signal is corrected so as to have a non-linear gain characteristic as an output characteristic with respect to the input, and the saturation level is lowered when the input saturation signal level is low saturation. With A saturation correction process for increasing the saturation level when the saturation signal level to be applied is intermediate saturation higher than the low saturation or high saturation higher than the intermediate saturation; Video adaptive control processing for controlling the saturation correction processing by setting independent parameters for each predetermined area according to the saturation feature information and the brightness feature information, and execute these processing procedures on a computer The saturation correction processing is a program for controlling the increase gain of the saturation level of the higher saturation than the intermediate saturation . A computer-readable recording medium on which the program according to claim 5 is recorded.

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