JP4377733B2 - Color adjustment module, image pickup apparatus, and program for realizing color adjustment - Google Patents

Description

The present invention allows a favorable image quality adjustment on the digital image, the color adjustment module Contact and imaging apparatus, and to a program for realizing the color adjustment.

  Currently, many electronic cameras (imaging devices) and development processing software (software that reads raw RAW images and performs various image processing) have additional image processing such as gradation adjustment, saturation and hue adjustment. It has been incorporated. These additional image processing can be correction processing aimed at accuracy, such as faithful color reproduction and input / output matching, and can improve the visual preference and visibility of images. There is also a purposed process. With digital images, these image processes can be performed easily, but with the original images, it is difficult to achieve the desired image quality.

  For example, processing for enhancing the saturation of an image is frequently used. Such processing is generally performed because images taken with an electronic camera feel that contrast and vividness are lacking even if they are close to the real thing, and those that are emphasized for normal use are preferred. Because it is easy. Unless necessary, a series of processing is automatically performed, and even a user without knowledge can easily handle it. As image processing, in addition to a method of simply emphasizing uniformly, for example, Patent Document 1 shows an example in which saturation weighting is performed according to the saturation, brightness, and hue of an image. In Patent Document 2, nonlinear saturation emphasis is performed in consideration of color space distortion and output device characteristics.

JP 2000-92337 A JP-A-6-118926

  As the image processing as described above, the method of simply and uniformly emphasizing is the safest. However, if the same processing is automatically performed in all cases, inconvenience may occur. For example, noise may be conspicuous in a digital camera or the like depending on shooting conditions, but in such a case, if it is simply emphasized uniformly, the noise may be conspicuous.

  In addition, in an imaging apparatus or an image display device in which the dynamic range of brightness and the color reproduction range are much narrower than the actual color space, various brightnesses and colors are pushed into a narrow range. For this reason, if the saturation is simply emphasized, the color reproduction range may protrude or the overall balance may be lost. The weighting as in Patent Document 1 is an example of a solution, but the illustrated weighting method is not always the best, and is based on the calculation of saturation and hue, which will be described later, and has a large circuit scale. There was a problem that it was easy to become.

  In addition, when performing image processing, the saturation adjustment does not affect the hue as a general rule, but if the hue is shifted if the saturation is simply emphasized due to distortion of the color space used, the hue may be shifted. Sometimes I want to change In the technique described in Patent Document 2, the saturation enhancement coefficient is merely a function of data related to saturation and hue (a *, b *), and the relationship between the shape of the specific function and the brightness is not shown. There was no problem.

The invention has been made in view of such problems of the prior art, and an object allows the preferred image quality adjustment on the digital image, the color adjustment module Contact and imaging devices, and color adjustment It is to provide a program for realizing.

  In order to achieve the above object, a color adjustment module according to the first embodiment of the present invention receives a light / dark component signal and a color component signal of an image, and calculates a coefficient corresponding to the light / dark component signal of the image as the color component. A color adjustment module that applies to a signal, changes the color component signal value, and outputs the changed color component signal, wherein the relationship between the coefficient and the light-dark component signal value is the light-dark component signal A portion where the coefficient increases with an increase in value is included, and a portion where the coefficient decreases with an increase in the light / dark component signal value is not included.

  As described above, in the color adjustment module according to the first embodiment, the light / dark component signal and the color component signal of the image are input to the color adjustment module, and the color adjustment module increases as the light / dark component signal value increases. A coefficient having a constant value is applied to the color component signal, and the changed color component signal is output. By adopting such a configuration, it is possible to adjust the saturation so as to exaggerate the visual effect that the color looks bright when the illuminance is high and the color appears dull when the illuminance is low. it can. Further, it is possible to prevent the color noise in the dark part from being emphasized.

  The color adjustment module according to the second embodiment of the present invention receives a light / dark component signal and a color component signal of an image, applies a coefficient corresponding to the light / dark component signal of the image to the color component signal, A color adjustment module that changes the color component signal value and outputs the changed color component signal, and the relationship between the coefficient and the light / dark component signal value is the coefficient near the upper limit and the lower limit of the light / dark component signal value. Is small and large when the light / dark component signal value is an intermediate value.

  As described above, in the color adjustment module according to the second embodiment, the light / dark component signal and the color component signal of the image are input to the color adjustment module, and the color adjustment module has a coefficient when the light / dark component signal value is near the upper limit and the lower limit. Is reduced. When the light / dark component signal value is an intermediate value, a large coefficient is applied to the color component signal. In this way, the color component signal changed by the coefficient is output. By adopting such a configuration, it is possible to suppress the saturation enhancement in the low and high luminance portions of the image, particularly in the region close to the upper and lower luminance limits, and to suppress the occurrence of color saturation. Further, it is possible to make the central subject with intermediate brightness stand out more vividly and sharpen the entire image.

  In the color adjustment module according to the second embodiment, the relationship between the coefficient and the light / dark component signal value is such that when the light / dark component signal value is less than a first predetermined value, the coefficient is the light / dark component signal value. Increases gradually, and when the light and dark component signal value is larger than a second predetermined value greater than the first predetermined value, the coefficient gradually decreases as the light and dark component signal value increases, When the light / dark component signal value is not less than a first predetermined value and not more than a second predetermined value, the coefficient takes a constant value.

  The color adjustment module applies a constant coefficient to the color component signal when the light / dark component signal value is within a predetermined range, and when the light / dark component signal value is equal to or less than a first predetermined value, A coefficient that increases with increasing signal value is applied to the color component signal. Further, when the light / dark component signal value is equal to or greater than a second predetermined value, a coefficient that decreases with respect to the increase of the light / dark component signal value is applied to the color component signal, and a changed color component signal is output. By adopting such a configuration, it is possible to suppress the saturation enhancement in the low and high luminance portions of the image, particularly in the region close to the upper and lower luminance limits, and to suppress the occurrence of color saturation. For this reason, the setting is simple and the circuit scale can be reduced.

  In addition, the color adjustment module according to the second embodiment includes a light / dark distribution investigation unit that sets a reference value based on a statistic of the light / dark component signal value within a predetermined range in the image, and the light / dark component signal value and The coefficient is determined based on the reference value.

  In this color adjustment module, the light / dark distribution investigation unit calculates a statistic (average value or mode) of a light / dark signal within a predetermined range in the image, sets a reference value based on the statistic, and the color adjustment module Determines the coefficient based on the reference value and the light / dark component signal value. With such a configuration, it is possible to change the saturation adjustment of the image according to the brightness characteristic of the image.

  The color adjustment module according to the second embodiment is characterized in that the coefficient increases as the light / dark component signal value is closer to the reference value. Thus, since the coefficient increases as the light / dark component signal value is closer to the reference value, the saturation enhancement of the main subject is enhanced more than others even when the exposure is higher or lower. You can turn on.

  If any of the color adjustment modules is less than a first predetermined value, the first restriction processing unit replaces the coefficient with the first predetermined value; and the coefficient is greater than a second predetermined value. Includes either or both of the second restriction processing unit replaced with the second predetermined value.

  The color adjustment module according to the first or second embodiment receives the input of the coefficient, and the first restriction processing unit compares the coefficient with a first predetermined value, and the coefficient is the first If it is less than a predetermined value, the first predetermined value is output as the coefficient, and otherwise, the coefficient is output as it is. In response to the input of the coefficient, the second restriction processing unit compares the coefficient with a second predetermined value, and if the coefficient is less than a second predetermined value, the second predetermined value is The coefficient is output as a coefficient, and the other coefficients are output as they are. In this way, by limiting the saturation coefficient to the first predetermined value (1) or more, it is possible to prevent the saturation from becoming too low and the dark part to become dark or the bright part from becoming too white. Moreover, excessive saturation enhancement can be avoided by limiting the saturation coefficient to the second predetermined value (specific value) or less.

  The image processing system according to the first embodiment of the present invention receives a light / dark component signal and a color component signal of an image, applies a coefficient corresponding to the light / dark component signal of the image to the color component signal, A color adjustment module that changes the color component signal value and outputs the changed color component signal, wherein the relationship between the coefficient and the light / dark component signal value is the coefficient for the increase of the light / dark component signal value. The color adjustment module includes a portion in which the coefficient increases, and does not include a portion in which the coefficient decreases as the light / dark component signal value increases.

  The image processing system according to the second embodiment of the present invention receives a light / dark component signal and a color component signal of an image, applies a coefficient corresponding to the light / dark component signal of the image to the color component signal, A color adjustment module that changes the color component signal value and outputs the changed color component signal, and the relationship between the coefficient and the light / dark component signal value is the coefficient near the upper limit and the lower limit of the light / dark component signal value. And a color adjustment module that is large when the light / dark component signal value is an intermediate value.

  The color adjustment module of the image processing system according to the first or second embodiment includes any one of the configurations described above.

  The image processing system according to the first embodiment and the image processing system according to the second embodiment are the functions of the color adjustment module according to the first embodiment and the color adjustment module according to the second embodiment, respectively. Is to do. For this reason, the image processing system which performs suitable saturation adjustment with respect to an image is obtained.

  The image processing system according to the first or second embodiment includes a light / dark signal adjustment unit that adjusts the light / dark component signal, and the color adjustment unit uses a coefficient corresponding to an output of the light / dark signal adjustment unit as the color component. It is applied to a signal. The color adjustment module adjusts the light / dark component signal by the light / dark signal adjusting unit, and the color adjusting unit applies a coefficient corresponding to the adjusted light / dark component signal to the color component signal. By adopting such a configuration, it is possible to adjust the gradation and to perform preferable saturation adjustment in consideration of the processing result.

  An image processing system according to a third embodiment of the present invention includes an image input unit that supplies a primary color or complementary color image signal, and a primary color or complementary color image signal supplied from the image input unit. A first color space conversion unit that converts a component signal and a color component signal; and a color adjustment that applies a coefficient corresponding to the light / dark component signal of the image to the color component signal to change the color component signal value A second color space conversion unit that integrates the light / dark component signal and the changed color component signal and reconverts them into a primary color or complementary color image signal, and outputs a primary color or complementary color image signal And an image output unit.

  In the image processing system according to the third embodiment, the image signal supplied from the image input unit is converted into a light / dark component signal and a color component signal by the first color space conversion unit, and converted into a light / dark component signal by the color adjustment unit. A corresponding coefficient is applied to the color component signal to change the color component signal value. Further, the color component signal changed by the second color space conversion unit and the light / dark component signal are integrated and reconverted into an image signal, which is output from the image output unit. With such a configuration, it is possible to perform preferable saturation adjustment in consideration of the brightness of the image.

  The image processing system according to the third embodiment further includes a light / dark signal adjustment unit that adjusts the light / dark component signal, and the color adjustment unit uses a coefficient corresponding to the output of the light / dark signal adjustment unit as the color component signal. It is characterized by being applied to. In this image processing system, the light / dark component adjustment unit adjusts the light / dark component signal, and the color adjustment unit applies a coefficient corresponding to the adjusted light / dark component signal to the color component signal. By adopting such a configuration, it is possible to adjust the gradation and to perform preferable saturation adjustment in consideration of the processing result.

  The image processing system according to the third embodiment is characterized in that the signal corresponding to the light / dark component signal is an output of the light / dark signal adjustment unit. In this image processing system, the result of adjusting the light / dark component signal by the light / dark signal adjusting unit is reflected, so that preferable saturation adjustment is possible.

  An imaging apparatus according to a first embodiment of the present invention includes an electronic imaging unit, a pre-processing unit that processes a signal from the electronic imaging unit to generate a primary color or complementary color image signal, and the pre-processing unit A first color space conversion unit that converts a primary color system signal or a complementary color system image signal supplied from the color signal into a light / dark component signal and a color component signal, and a coefficient corresponding to the light / dark component signal of the image with respect to the color component signal And a second color for re-converting the light / dark component signal and the changed color component signal into an image signal of a primary color system or a complementary color system by integrating the color adjustment unit for changing the color component signal value. The image processing apparatus includes a space conversion unit and a post-processing unit that performs processing according to an output form on an image signal of a primary color system or a complementary color system and outputs the processed signal.

  In the imaging apparatus according to the first embodiment, a primary color system or complementary color system image signal that has been captured and preprocessed by a pre-processing unit is converted into a light / dark component signal and a color component signal by a first color space conversion unit, The color adjusting unit applies a coefficient corresponding to the light / dark component signal to the color component signal to change the color component signal value. Also, the second color space conversion unit integrates the light / dark component signal and the changed color component signal and reconverts them into primary color or complementary color image signals, and the post-processing unit performs processing according to the output form. Output. By adopting such a configuration, it is possible to perform preferable saturation adjustment in consideration of the brightness of the image taken by the imaging apparatus.

  The imaging apparatus according to the first embodiment stores setting information at the time of imaging, and changes the relationship between the light / dark component signal value and the coefficient according to the setting information at the time of imaging. As described above, since the relationship between the coefficient and the light / dark component signal value is changed depending on the setting at the time of shooting, it is possible to make a preferable saturation adjustment suitable for the shooting scene. Further, it is possible to prevent the saturation adjustment from being deteriorated.

  The imaging apparatus according to the first embodiment includes a light / dark signal adjusting unit that adjusts the light / dark component signal, and the color adjusting unit sets a coefficient corresponding to an output of the light / dark signal adjusting unit to the color component signal. It is characterized by being applied. In this way, the light / dark component signal is adjusted by the light / dark signal adjusting unit, and the color adjusting unit applies a coefficient corresponding to the adjusted light / dark component signal to the color component signal. For this reason, it is possible to adjust the gradation and perform preferable saturation adjustment in consideration of the processing result.

  The color adjustment module according to the third embodiment of the present invention receives a light / dark component signal and a plurality of color component signals of an image, and applies a coefficient corresponding to the light / dark component signal to each signal related to the color. A color adjustment module that changes each color component signal value and outputs the changed color component signal, wherein the relationship between the coefficient and the light / dark component signal is different for each color component signal.

  In the color adjustment module according to the third embodiment, a light / dark component signal of an image and a plurality of signals related to colors are input to the color adjustment module. The color adjustment module applies a coefficient based on the relationship between the light / dark component signal value and the coefficient corresponding to each of the plurality of signals related to the color to each of the color component signals to obtain each signal value related to the color. change. Then, the changed color component signal is output. With such a configuration, it is possible to adjust the image with good appearance by shifting the hue when performing saturation adjustment.

  In the color adjustment module according to the third embodiment, the relationship between the coefficient and the light / dark component signal is that the first coefficient for the first signal among the plurality of signals related to the color in the region where the light / dark component signal value is large. Is larger than the second coefficient for the second signal and the light and dark component signal value is small, the second coefficient is larger than the first coefficient.

  Thus, in the region where the light / dark component signal value is large, the first coefficient for the first signal relating to the color is set larger than the second coefficient for the second signal, and in the region where the light / dark component signal value is small, The coefficient of 2 is made larger than the first coefficient. For this reason, the phenomenon in which the hue appears to change in a specific direction with the intensity of light can be exaggerated on the image, and the image can be adjusted with good appearance.

  An image processing system according to a fourth embodiment of the present invention receives a light / dark component signal and a plurality of color component signals of an image, and applies a coefficient corresponding to the light / dark component signal to each signal related to the color. A color adjustment module that changes each color component signal value and outputs the changed color component signal, wherein a relationship between the coefficient and the light / dark component signal is different for each color component signal. It is characterized by. This image processing system performs the operation of the color adjustment module according to the third embodiment. For this reason, the image processing system which performs suitable saturation adjustment with respect to an image is obtained.

  An image processing system according to a fifth embodiment of the present invention includes an image input unit that supplies a primary color or complementary color image signal, and a primary color or complementary color image signal supplied from the image input unit. A first color space conversion unit that converts a component signal and a plurality of color component signals; and applying a coefficient corresponding to the light / dark component signal for each of the plurality of color component signals to each color component signal A color adjustment unit that changes a value, a second color space conversion unit that integrates the light / dark component signal and the changed color component signal value and reconverts them into an image signal of a primary color system or a complementary color system, and a primary color system or And an image output unit that outputs a complementary color image signal, wherein the relationship between the coefficient and the light / dark component signal is different for each of the plurality of color component signals.

  In the image processing system according to the fifth embodiment, the primary color system or complementary color system image signal supplied from the image input unit is converted into a light / dark component signal and a plurality of color-related signals by the first color space conversion unit, A color adjusting unit obtains a coefficient based on the relationship between the light / dark component signal corresponding to each signal related to the color and the coefficient. The coefficient value is applied to each color component signal to change each signal value, and the light and dark component signal and the changed color component signal are integrated by a second color space conversion unit to obtain an image of a primary color system or a complementary color system. Reconvert to signal. The reconverted image signal is output as a primary color or complementary color image signal by the image output unit. With such a configuration, it is possible to adjust the image with good appearance by shifting the hue when performing saturation adjustment.

  An imaging apparatus according to a second embodiment of the present invention includes an electronic imaging unit, a pre-processing unit that processes a signal from the electronic imaging unit to generate a primary color or complementary color image signal, and the pre-processing unit A first color space conversion unit that converts a primary color or complementary color image signal supplied from the image signal into a light / dark component signal and a plurality of color component signals, and the image for each of the plurality of color component signals A color adjustment unit that changes each color component signal value by applying a coefficient corresponding to each of the light and dark component signals, and an image signal of a primary color system or a complementary color system by integrating the light and dark component signal and the changed color component signal A second color space conversion unit that re-converts the image, and a post-processing unit that outputs the primary color or complementary color image signal according to an output form, and outputs the coefficient and the light / dark component signal Of the color components differ for each of the plurality of color component signals And wherein the door.

  In the imaging apparatus according to the second embodiment, the captured primary color or complementary color image signal is converted into a light / dark component signal and a color component signal by the first color space conversion unit, and the color adjustment unit relates to the color. The relationship between the light / dark component signal and the coefficient is changed for each signal, a coefficient is obtained based on the relationship, and each color component signal value is changed by applying the coefficient. The light and dark component signals and the changed color component signals are converted again into primary color or complementary color image signals by the second color space conversion unit, and processed according to the output form by the post-processing unit and output. Is. With such a configuration, it is possible to perform preferable saturation adjustment in consideration of the brightness and hue shift of the image captured by the imaging apparatus.

  The imaging apparatus according to the second embodiment holds setting information at the time of imaging, and changes the relationship between the coefficient corresponding to each color component signal and the light / dark component signal according to the setting information at the time of imaging. It is characterized by. In this way, setting information at the time of imaging is held, and the relationship between the signal light / dark component signal and the coefficient is changed for each of a plurality of signals related to color according to the setting information at the time of imaging. For this reason, it is possible to adopt a more preferable hue shifting method in accordance with the shooting scene, and to make it possible to adjust the apparent saturation.

  A program according to the first embodiment of the present invention includes a procedure for reading an image signal into a computer, a procedure for performing a first color space conversion on the image signal, and a first image that has undergone the color space conversion. A procedure for determining a saturation coefficient according to a signal; a procedure for applying the determined saturation coefficient to the second image signal subjected to color space conversion; and the first image signal and the second image signal. The color adjustment is realized by executing the procedure for performing the second color space conversion on the image.

  The program according to the first embodiment causes a computer to execute the operation of the color adjustment module as shown in FIG. 1 and the image processing system using the color adjustment module. For this reason, the saturation adjustment for the image can be easily performed by the computer without requiring a special device for the color adjustment module as shown in FIG.

  In addition, the program according to the first embodiment adds to the computer a procedure for performing pre-processing on the read image signal and a procedure for adjusting a light / dark signal on the color image-converted first image signal. And executing it. This program causes a computer to execute the operation of the imaging apparatus as shown in FIG. Therefore, the saturation adjustment for the image can be easily performed by the computer without requiring a special device of the imaging apparatus as shown in FIG.

  A program according to a second embodiment of the present invention includes a procedure for reading an image signal into a computer, a procedure for performing a first color space conversion on the image signal, and a first image that has undergone the color space conversion. A procedure for determining a first saturation coefficient from the signal, a procedure for determining a second saturation coefficient from the first image signal subjected to the color space conversion, and the determined first saturation coefficient A procedure for applying the color space transformed second image signal; a procedure for applying the determined second saturation coefficient to the color space transformed third image signal; The color adjustment is realized by executing a procedure for performing the second color space conversion on the first image signal to the third image signal.

  The program according to the second embodiment causes a computer to execute the operation of the color adjustment module as shown in FIG. 5 and the image processing system using the color adjustment module. For this reason, the saturation adjustment for the image can be easily performed by the computer without requiring a special device for the color adjustment module as shown in FIG.

  A program according to the second embodiment is characterized in that a computer is added with a procedure for performing a pre-processing on the read image signal and a procedure for adjusting a light / dark signal. This program causes the computer to execute the operation of the imaging apparatus as shown in FIG. Therefore, the saturation adjustment for the image can be easily performed by the computer without requiring a special device of the imaging apparatus as shown in FIG.

  A program according to a third embodiment of the present invention includes a procedure for reading an image signal into a computer, a procedure for performing a first color space conversion on the image signal, and performing the first color space conversion on all pixels. A procedure for determining whether or not the processing has been completed, a procedure for calculating a reference lightness for the first image signal subjected to the first color space conversion, and for the first image signal based on the reference lightness A procedure for determining a saturation coefficient; a procedure for applying the determined saturation coefficient to the second image signal subjected to the first color space conversion; and the first image signal and the second image. Color adjustment is realized by executing a procedure for performing second color space conversion on the signal.

  A program according to the third embodiment causes a computer to execute the operation of a color adjustment module as shown in FIG. 11 and an image processing system using the color adjustment module. For this reason, the saturation adjustment for the image can be easily performed by the computer without requiring a special device for the color adjustment module as shown in FIG.

  In the color adjustment module of the present invention, an image processing system and an imaging apparatus using the same, and a program for realizing color adjustment, saturation adjustment of an image that looks better is performed in consideration of visual characteristics and a subject. It becomes possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing a color adjustment module and an image processing system using the same according to a first embodiment of the present invention. As shown in FIG. 1, the image processing system includes an image input unit 001, a first color space conversion unit 002, a saturation coefficient determination unit 003, a saturation coefficient application unit 004, and a second color space conversion. Part 005 and an image output part 006. Among them, the saturation coefficient determination unit 003 and the saturation coefficient application unit 004 constitute a color adjustment module that is a first embodiment of the present invention. The color adjustment module is mounted as a composite part, for example, on the same substrate.

  The RGB image signal 011 input from the image input unit 001 is converted into a light / dark component signal 012 (L * signal, first image signal) and two color-related signals (a * b *) by the first color space conversion unit 002. Signal, second image signal) 013. The saturation coefficient determination unit 003 outputs a saturation coefficient g014 corresponding to the input of the L * signal 012 in the arithmetic circuit. The saturation coefficient application unit 004 applies (for example, multiplies) the saturation coefficient g014 to the a * b * signal 013. The unprocessed L * signal 012 and the coefficient-applied a * 'b *' signal 015 are integrated by the second color space conversion unit 005 and are output in RGB format (R'G'B 'signal) ) 016 and sent to the image output unit 006.

The L * a * b * signal used here is used as an index representing the color three-dimensionally, and a conversion equation is defined from the RGB signal via another coordinate system XYZ coordinate system. L * represents brightness / darkness information of the color of the object in terms of brightness. a * and b * are chromaticness indices, and are expressed by the following equation (1):
Cab * = √ (a * ² + b * ² ), hab * = arctan (b * / a *) (1)
It is related to saturation Cab * and hue angle hab *.

Saturation can be adjusted by applying a coefficient (for example, multiplication) to the above a * and b *. In this case, if multiplication is simply performed, the coefficient is g, and the saturation Cab * after the change is expressed by Equation (2),
a * '= g × a *, b *' = g × b *
Cab * '= √ (a *' ² + b * ' ² ) = g × Cab * (2)
become that way.

  There are several types of relationships between the saturation coefficient g104 calculated by the coefficient determination unit 003 and the lightness signal (L * signal) 012 depending on the application. An example is shown in the characteristic diagram of FIG. In the characteristic diagram of FIG. 2, the horizontal axis represents the lightness L *, and the vertical axis represents the saturation coefficient g. L * is adjusted by the color space conversion unit 002 to take a value of 0 to 100. In the characteristic diagram of FIG. 2, g = 1.0 corresponds to no saturation adjustment.

  In FIG. 2A, the saturation coefficient g is increased as L * is larger, that is, the brightness is higher, and the saturation coefficient g is decreased at lower brightness. By adopting such characteristics, the following effects can be obtained. Usually, when an object is viewed, it is said that there is a visual effect that the color looks vivid when the illuminance is high and the color appears dull when the illuminance is low. The pattern in FIG. 2A exaggerates this effect on the image, and the image can be adjusted with good appearance by making it appear more vivid when the subject illumination is high.

  In addition, in an image taken with an electronic camera, there is a phenomenon that noise is conspicuous in a dark part. In such a case, if a large saturation coefficient is multiplied, noise is also emphasized. Therefore, as in the characteristic of FIG. 2A, it is possible to avoid enhancing noise by not multiplying a large coefficient in the low brightness area. It should be noted that where the brightness is very high (L *> L1), excessive saturation enhancement is avoided by making the saturation coefficient g constant without increasing it.

  The color adjustment module and the image processing system having this color adjustment module according to the first embodiment described in the claims of the present invention correspond to FIGS. 1 and 2 (1). That is, in claim 1 and claim 7, the light / dark component signal and the color component signal of the image correspond to the L * signal 012 and the a * b * signal 013 shown in FIG. The changed color component signal corresponds to the a * 'b *' signal 015 shown in FIG. 1, and the coefficient corresponds to the saturation coefficient 014 of FIG. The relationship between the coefficient and the light / dark component signal value is shown in the characteristic of FIG.

  2 (2), the saturation coefficient g is maximized when the lightness L * is a reference lightness value Lp (for example, around 60), and when the lightness L * is 0 or 100, the saturation. The coefficient g is set to 1. By adopting such characteristics, the following effects can be obtained. There are limits to the colors that can be reproduced in reality, and the values that saturation can take are small near the upper and lower limits of lightness.

  In addition, depending on the output device, the color reproduction range is further narrowed. Colors that are too saturated and cannot be reproduced will appear to be out of hue or crushed. On the other hand, in the range of brightness 50 and 60, the range in which saturation can be obtained is relatively wide. Therefore, as shown in the characteristic of FIG. 2 (2), the saturation enhancement is strengthened in the lightness region with a wide color reproduction range, and the saturation enhancement is hardly performed in the lightness region with a narrow color reproduction range. -The occurrence of color collapse in high brightness areas can be reduced.

  Moreover, the following effects are also acquired by setting it as a characteristic like FIG. 2 (2). In general, when the exposure is appropriate, the main subject is likely to have a relatively intermediate brightness. Therefore, by increasing the saturation of the intermediate lightness region, the main subject can be made more conspicuous and the whole image can be sharpened. Note that the lightness at which the saturation coefficient g should be maximized is not limited to around 60, and it may be preferable to increase or decrease the lightness. Even in such a case, the saturation coefficient can be reduced toward the upper and lower limits of lightness, and the effect of avoiding color collapse can be provided.

The color adjustment module and the image processing system having this color adjustment module in the second embodiment of the present invention correspond to FIG. 1 and FIG. 2 (2). Chi Sunawa, a color component signal L * signal 012, a * b * signal 013 brightness component signal and the color component signals as shown in FIGS. 1 corresponds, constructed change images are shown in Figure 1 * 'b *' signal 015 corresponds. The coefficient corresponds to the saturation coefficient 014 in FIG. The relationship between the coefficient and the light / dark component signal value is shown in the characteristic of FIG.

  In the characteristic shown in FIG. 2 (3), the saturation is uniformly increased in the intermediate lightness region of the image, and the emphasis is gradually enhanced in the low and high lightness regions (regions where the lightness L * is less than L1 and larger than L2 in the figure). I refrain. In other words, in the L1 and L2 regions at the upper and lower limits of the low / high lightness region, the saturation is not emphasized or rather weakened. With such characteristics, as in the case of FIG. 2 (2), calculation is performed by using a fixed coefficient in the halftone while avoiding color saturation and noise in the low and high brightness regions of the image. The circuit scale can be reduced.

  In the characteristic shown in FIG. 2 (4), clipping processing is performed to 1 so that the saturation coefficient g does not become less than 1, and clipping processing is performed to gmx so as not to exceed a large value gmx. This clip processing is used in combination with other characteristics of FIG. Specifically, a clip processing unit 1 that replaces the saturation coefficient g014 with 1 when the saturation coefficient g014 is less than 1 between the saturation coefficient determination unit 003 and the saturation coefficient application unit 004 of FIG. If the saturation coefficient g014 is larger than the value gmx, a clip processing unit 2 is added to replace the saturation coefficient g014 with gmx. The clip processing unit itself includes a reference value and a comparator, and compares the input value with the reference value and outputs a larger value or a smaller value. The two clip processing units may be arranged in series or in parallel. Further, it may be inside the saturation coefficient determination unit 003 and the saturation coefficient application unit 004.

  FIG. 15 is a configuration diagram showing an arrangement example of the clip processing unit 1 (008) and the clip processing unit 2 (009). When the two clip processing units of the clip processing unit 1 and the clip processing unit 2 are arranged in series, as shown in FIG. 15, the clip processing unit 1 determines whether the saturation coefficient g014 is less than 1 or more than 1. First determination means is included. In addition, the clip processing unit 2 includes second determination means for determining whether the saturation coefficient g014 is larger than gmx. When the first determination unit determines that the saturation coefficient g014 is 1 or more, the saturation coefficient g014 is passed through the clip processing unit 1 and the saturation coefficient g ′ is input to the clip processing unit 2. When the first determination means determines that the saturation coefficient g014 is less than 1, the clip processing unit 1 outputs 1 and inputs it to the clip processing unit 2. When the second determination unit determines that the saturation coefficient g ′ is greater than the gmx, the clip processing unit 2 replaces the saturation coefficient g ′ with gmx and outputs g ″.

  Thus, by limiting the saturation coefficient g to 1 or more, there is an effect of preventing the dark part from appearing darkened and the bright part from becoming too white by reducing the saturation too much. Such processing basically does nothing, and can be said to be a processing method for adjusting the saturation only in the necessary lightness region. Furthermore, limiting the saturation coefficient to a specific value or less has the effect of avoiding excessive saturation enhancement. When using a LUT (Look Up Table) as described below, the setting including the clip characteristics may be used from the beginning.

  In the characteristic shown in FIG. 2 (5), the overall saturation coefficient g is kept small, and the rate of change of the saturation coefficient g due to lightness L * is increased. When the saturation of the entire original image is very high and is easily saturated with saturation enhancement, the contrast of saturation due to lightness can be increased to enhance the saturation. In the above description, the saturation coefficient determination unit 003 calculates the saturation coefficient g by the arithmetic circuit. However, the saturation coefficient g corresponding to the lightness L * signal value may be selected with reference to the LUT. Good. The latter tends to have arbitrarily complex characteristics.

  FIG. 3 is a configuration diagram showing an example of an electronic camera (imaging device) to which the image processing system of the present invention is applied. Parts having the same functions as those in FIG. 1 are given the same numbers, and detailed explanations are omitted. An image photographed through the optical system 101 and the image sensor 102 includes an initial signal processing unit 103 that performs analog processing and A / D conversion, an interpolation processing unit 104, a white balance (WB) processing unit 105, and a first color space. The image recording unit passes through the conversion unit 106, the light / dark signal adjustment unit 107, the saturation coefficient determination unit 003, the saturation coefficient application unit 004, and the second color space conversion unit 005, and the post-processing unit 108 that performs compression and the like. Is output to 109 and recorded on a recording medium or the like. The optical system 101 and the imaging element 102 constitute an electronic imaging unit of the imaging apparatus. The initial signal processing unit 103, the interpolation processing unit 104, and the white balance (WB) processing unit 105 correspond to a pre-processing unit that processes signals from the electronic imaging unit.

  These respective blocks shown in FIG. 3 are also bidirectionally connected to a control unit 121 such as a microcomputer. Further, an external I / F unit 122 having an interface for switching a power switch, a shutter button, various modes at the time of shooting, and the like is connected to the control unit 121 in both directions.

  In FIG. 3, the flow of signals will be described. A shooting mode, shooting conditions, and the like are set via the external I / F unit 122, and shooting is performed by pressing the shutter button. A video signal photographed through the optical system 101 and the image sensor 102 is read as an analog signal by the initial signal processing unit 103, amplified, and converted into a digital signal. Next, the digital signal is interpolated by the interpolation processing unit 104 and divided into three video signals of R, G, and B. The WB processing unit 105 calculates WB coefficients so that the achromatic RGB ratio in the image is appropriate. Also, based on the WB setting that was set before shooting and transferred to the control unit 121 via the input I / F unit 122, the RGB signal of the image is multiplied by the WB coefficient, and the first color space conversion unit 106 is multiplied. Forward.

  In the first color space conversion unit 106, the RGB three video signals 131 of each pixel in the image are converted into signals of a predetermined color space, for example, the L * a * b * signal described in the first embodiment (first 1 image signal L *, second image signal a * b *). However, the input RGB here depends on the imaging system and is different from the RGB used in the definition of L * a * b *. Therefore, if necessary, conversion based on the characteristics of the imaging system, such as adding correction calculations, etc. To do. By such processing, the RGB signal is divided into a light / dark component L * signal 132 and a color component a * b * signal 133. The L * signal 132 is sent to the light / dark signal adjustment unit 107. The light / dark signal adjustment unit 107 adjusts the light / dark component of the image such as gradation adjustment and edge enhancement, and the L * ′ signal 134 of the light / dark component after adjustment is determined by the second color space conversion unit 005 and the saturation coefficient determination. Output to part 003.

  The saturation coefficient determination unit 003 determines the saturation coefficient g corresponding to the L * ′ signal 134, and the determined saturation coefficient data 135 is transferred to the coefficient application unit 004. On the other hand, the saturation coefficient application unit 004 adjusts the saturation by applying the saturation coefficient data 135 to the input of the a * b * signal 133, and outputs the adjusted a * 'b *' signal 136 to the second signal. To the color space conversion unit 005. In the second color space conversion unit 005, the adjusted L * ′ signal 134 and the a * ′ b * ′ signal 136 are integrated and converted into the RGB space signal 137 again. If necessary, the reproduction color gamut is compressed and adjusted. This processing is performed in order to match the recorded image with the color space of an output device such as a standard monitor that has a much narrower range of saturation than the processing color space.

  In general, processing is performed to shift the saturation and lightness of a color outside the reproducible range of the output device or a color close thereto to the reproducible range so that there is no sense of incongruity. The converted RGB signal 137 is transferred to the post-processing unit 108 where it is subjected to a known compression process and recorded and stored in a recording medium such as a memory card. Also in this embodiment, various patterns as shown in FIG. 2 can be considered as the relationship between the saturation coefficient and the lightness L * signal. In FIG. 3, the primary color system (RGB) is used as the image sensor, but a complementary color (CYM) image sensor may be used. Also in this case, L * a * b * color conversion is performed on CYM in color space coordinates.

  In the second embodiment, the saturation coefficient is determined only by the lightness L * signal. However, the optimum relationship between the L * signal and the saturation coefficient differs depending on the main subject and shooting scene. For example, a scene with a high saturation is preferred for snapping of the scenery, but for people, it is more pleasing to look bright and not too strong. For example, if the camera can set the shooting mode such as landscape / portrait / night view, the information of the shooting scene can be used by capturing the information. Alternatively, another means for estimating the scene from the image may be provided.

  Therefore, in the third embodiment, the saturation coefficient determination unit 003 in FIG. 3 obtains information such as various mode settings from the control unit 121, and determines the saturation coefficient g based on these information. A specific example of such processing is shown in the characteristic diagram of FIG. In FIG. 4A, a plurality of brightness L * signal dependency characteristics such as curves of “person” and “landscape” are prepared as relational expressions and LUTs. Based on such characteristics, an arithmetic expression or LUT to be used is switched according to the setting information, or a correction expression is applied.

  In addition, the L * signal dependency characteristics may be changed depending on the shooting conditions such as ISO sensitivity, WB, and whether or not a strobe is used. For example, when the ISO sensitivity of the camera is high, noise becomes conspicuous. Therefore, as shown in FIG. 4B, when the ISO sensitivity is high, the characteristic of the lightness L * signal is switched. By such processing, adjustment adapted to the image becomes possible.

  It is more desirable for the electronic camera as in the second and third embodiments to include means for invalidating the saturation adjustment and the light / dark signal adjustment as necessary. For example, this means is operated from the external I / F 122 to set the saturation adjustment to OFF, and the saturation coefficient determination unit 003 obtains the setting information from the control unit 121 and fixes the saturation coefficient g to 1. To do. Alternatively, the input image signal 133 may be output as it is by the saturation coefficient application unit 004 under the control of the control unit 121.

An image processing system according to the third embodiment of the present invention corresponds to FIG. Chi words, images input image input unit 001 of FIG. 1, the first color space conversion unit color space conversion unit 002 of FIG. 1 corresponds. Further, the light / dark component signal and the color component signal of the image are the L * signal 012 and the a * b * signal 013 shown in FIG. 1, respectively, and the changed color component signal is the a * 'b *' signal shown in FIG. 015 is applicable. Further, the saturation adjustment unit corresponds to the saturation coefficient determination unit 003 and the saturation coefficient application unit 004 shown in FIG. 1, and the second color space conversion unit uses the color space conversion unit 005 of FIG. 1 corresponds to the image output unit 006 in FIG. The coefficient corresponds to the saturation coefficient 014 in FIG.

  The image processing system may include the light / dark signal adjustment unit 007 described with reference to FIG. The configuration diagram of FIG. 13 is an example of a case where the result of the brightness adjustment unit 007 is reflected in the determination of the saturation coefficient. The light / dark signal adjusting unit 107 adjusts the light / dark component of the image, such as gradation adjustment and edge enhancement as described above, and the L * ′ signal of the light / dark component after adjustment is converted into the second color space converting unit 005 and the chroma signal. Output to the degree coefficient determination unit 003. Further, the configuration diagram of FIG. 14 is an example when the result of the brightness adjustment unit 007 is not reflected in the determination of the saturation coefficient. In the example of FIG. 14, the light / dark component L * ′ signal adjusted by the light / dark signal adjustment unit 107 is output to the second color space conversion unit 005. In these examples, the brightness L * ′ adjusted by the brightness adjustment unit 007 is used as an input to the color space conversion unit 005 in any case.

The imaging apparatus according to the first embodiment of the present invention corresponds to FIG. Chi words, electronic imaging unit optical system 101 and the image sensor 102 of FIG. 3, the pre-processing unit is an initial signal processing unit 103 of FIG. 3, the interpolation processing unit 104, the white balance (WB) processing unit 105 corresponds . The color space conversion unit 106 corresponds to the first color space conversion unit, and the saturation coefficient determination unit 003 and the saturation coefficient application unit 004 correspond to the color adjustment unit. The color space conversion unit corresponds to the color space conversion unit 005, and the post-processing unit corresponds to the post-processing unit 108. The primary color or complementary color image signal is the RGB signal 131, the light / dark component signal is the L * signal 132, the color component signal is the a * b * signal 133, and the changed color component signal is the a * 'b *' signal 136. The RGB signal 137 corresponds to the re-converted primary color or complementary color image signal.

  In the first to third embodiments, the same saturation coefficient is applied to the two color component signals. In the fourth embodiment, the L * dependency of the saturation coefficient for the two color component signals is changed, and different saturation coefficients are applied to the two color signals depending on L *. The configuration of the color adjustment module and the image processing system using the same in this embodiment is shown in the configuration diagram of FIG. The overall configuration is the same as in FIG.

  In FIG. 5, a saturation coefficient determination unit 201 and a saturation coefficient application unit 202 are used instead of the saturation coefficient determination unit 003 and the saturation coefficient application unit 004. The saturation coefficient application unit 202 includes a first application unit 203 and a second application unit 204. The same blocks as those in FIG. 1 are given the same numbers. The RGB image signal 011 input from the image input unit 001 is converted into a light / dark L * signal 012 and a color a * b * signal 013 by a color space conversion unit 002. The saturation coefficient determination unit 201 outputs two saturation coefficients 211 and 212 corresponding to the input of the lightness L * signal 012.

  The saturation coefficient application unit 202 applies (eg, multiplies) the saturation coefficient 211 to the a * signal of the a * b * signal 013 in the first application unit 203, and the a * b * in the second application unit 204. The saturation coefficient 212 is applied to the b * signal of the signal 013. The unprocessed L * signal 012 and the coefficient-applied a * 'b *' signal 213 are integrated by the color space conversion unit 005 and converted to an RGB signal (R'G'B 'signal) 016 for output. And sent to the image output unit 006.

If the saturation coefficient 211 is g1 and the saturation coefficient 212 is g2, the adjusted saturation Cab * 'and hue hab *' can be expressed by equation (3).
a * '= g1 × a *, b *' = g2 × b *
Cab * '= √ ((g1 × a *) ² + (g2 × b *) ² ),
hab * '= arctan ((g2 × b *) / (g1 × a *)) (3)
become that way. The method of determining the saturation coefficients 211 and 212 may be performed by two systems of arithmetic circuits, or may refer to an LUT in which two coefficients corresponding to the L * signal 012 are described.

A color adjustment module and an image processing system (fourth embodiment) having this color adjustment module according to the third embodiment of the present invention correspond to FIGS. Chi words, brightness component signal and the color component signals of images is applicable is L * signal 012, a * b * signal 013 shown in FIG. 5, respectively, modified color component signals is shown in Figure 5 a * The 'b *' signal 213 is applicable. The coefficients correspond to the saturation coefficients 211 and 212 in FIG.

An image processing system according to the fifth embodiment of the present invention corresponds to FIGS. Chi words, images input unit has an image input unit 001 in FIG. 5, the first color space conversion unit corresponds the color space conversion unit 002. Further, the light / dark component signal and the color component signal of the image correspond to the L * signal 012 and the a * b * signal 013 shown in FIG. 5, respectively, and the changed color component signal corresponds to the a * 'b *' signal 213. Further, the color adjustment unit corresponds to the saturation coefficient determination unit 201 and the saturation coefficient application unit 202 shown in FIG. 5, the second color space conversion unit is the color space conversion unit 005, and the image output unit is the image output unit. 006 is applicable. The coefficients correspond to the saturation coefficients 211 and 212 in FIG.

  FIGS. 6 (1) to 6 (4) are characteristic diagrams showing patterns of examples of the relationship between the saturation coefficients g1 and g2 and the lightness L * signal 012. FIG. The horizontal axis of the characteristic diagram is the lightness L *, and the vertical axis is the saturation coefficient g1 or g2. In the figure, the solid line shows the characteristic of the saturation coefficient g1 with respect to a *, and the broken line shows the characteristic of the saturation coefficient g2 with respect to b *. In the characteristics of FIGS. 6A and 6B, the lightness L * is large, that is, in the bright region, the saturation coefficient g2 for b * is larger than the saturation coefficient g1 for a *, and conversely in the region where L * is small. Increase the saturation coefficient g1 for a *.

  By adopting such characteristics, the following effects can be obtained. In general, it is known that the hue appears to change slightly as the light intensity changes. When the brightness increases, orange and yellow-green appear yellow, and blue-green and blue-violet appear blue. In addition, when the brightness decreases, orange and magenta tend to appear red, and yellow green and blue green tend to appear green. This means that the b * axis feels stronger in the region where the lightness L * is large, and the a * axis feels stronger in the region where the lightness L * is small. The characteristics shown in FIGS. 6A and 6B have an effect of exaggerating such a phenomenon. Further, in FIG. 6 (2), as in FIG. 2 (1), the brighter areas are made brighter by increasing the saturation coefficients g1 and g2, thereby adjusting the image with better appearance.

  The characteristics shown in FIGS. 6 (3) and 6 (4) are opposite to those shown in FIGS. 6 (1) and 6 (2). That is, in the region where the lightness L * is large, the saturation coefficient g1 for a * is made larger than the saturation coefficient g2 for b *. In the region where the lightness L * is small, the saturation coefficient g2 for b * is increased. The reason for this is that, contrary to FIGS. 6 (1) and (2), the phenomenon in which the hue appears to slightly change as the light intensity changes is alleviated. For example, it is preferable that very light skin color and sunny grass do not shift in the yellow direction. However, the characteristics of FIGS. 6 (3) and (4) are rather different from those of FIGS. 6 (1) and (2). Suitable for the case where a characteristic opposite to the characteristic is desired. In the characteristic of FIG. 6 (4), the effect of making the brighter area appear more vivid is the same as the characteristic of FIG. 6 (2).

  In addition, even if the hue is constant in the calculation with the same saturation coefficient, it may be felt that the hue shifts depending on the color space used. This is because the color space is not necessarily uniform with respect to human senses and has distortion. In that case, the two saturation coefficients may be changed so as to correct the distortion.

  The fifth embodiment of the present invention is an electronic camera (imaging device) to which the image processing system of the fourth embodiment is applied, and FIG. 7 is a configuration diagram showing the configuration. Although the basic configuration is the same as that in FIG. 3, the saturation coefficient determination unit 201 and the saturation coefficient application unit 202 in FIG. 5 are used instead of the saturation coefficient determination unit 003 and the saturation coefficient application unit 004. Blocks having the same functions as in FIG. 3 are given the same numbers.

The saturation coefficient determination unit 201 receives the L * ′ signal 134 adjusted by the light / dark signal adjustment unit 107, determines two saturation coefficients 211 and 212 corresponding to the L * ′ signal 134, and outputs them to the saturation coefficient adaptation unit 202.
The saturation coefficient application unit 202 applies the saturation coefficient 211 to the a * signal of the a * b * signal 133, and applies the saturation coefficient 212 to the b * signal of the a * b * signal 133. This changes the lightness dependency of the saturation coefficient for the two color signals a * b *, and different saturation coefficients are applied to the two color signals depending on the lightness.

  Further, considering that the effective hue shift method varies depending on the shooting scene and conditions, the saturation coefficient determination unit 201 in FIG. 7 performs various mode settings and the like from the control unit 121 as in the third embodiment. Obtain information and switch the arithmetic expression or LUT to be used accordingly, or apply a correction expression. For example, as shown in the characteristic diagram of FIG. 8, the relationship between the lightness L * and the saturation coefficient g with respect to the signals a * and b * is made different between mode A (for example, person) and mode B (for example, landscape). Thus, the saturation adjustment adapted to the image is performed.

An imaging apparatus according to the second embodiment of the present invention corresponds to FIG. Chi words, electronic imaging unit optical system 101 and the image sensor 102 in FIG. 7, preprocessing unit initial signal processing unit 103, the interpolation processing unit 104, a white balance (WB) processing unit 105 corresponds. Further, the first color space conversion unit corresponds to the color space conversion unit 106 in FIG. 7, and the color adjustment unit corresponds to the saturation coefficient determination unit 201 and the saturation coefficient application unit 202. Further, the second color space conversion unit corresponds to the color space conversion unit 005 in FIG. 7, and the post-processing unit corresponds to the post-processing unit 108. Also, the RGB signal 131 is the primary color or complementary color image signal, the L * signal 132 is the light / dark component signal, the a * b * signal 133 is the color component signal, and the a * 'b *' signal is the changed color component signal The RGB signal 137 corresponds to the re-converted primary color or complementary color image signal. The coefficients correspond to the saturation coefficients 211 and 212 in FIG.

  In the example of FIG. 2 (2), which is the first embodiment, the reference lightness Lp at which the saturation coefficient g is maximum is determined to be a specific value. However, the entire image or a specific range (for example, including the image center) is included in advance. The average value or mode value of the brightness of the pixels in the predetermined area) is calculated, and the reference brightness Lp in FIG. 2 (2) is determined based on the calculated value. The saturation coefficient g is increased as L * is closer to Lp. You may make it enlarge. By adopting such characteristics, it is possible to enhance the saturation enhancement of the main subject more than others, even in an image where exposure is higher or lower.

  FIG. 11 shows a configuration diagram of the sixth embodiment. FIG. 11 is obtained by adding a buffer 020 and a lightness distribution survey unit 021 to the configuration of FIG. 1, and the same parts as those in FIG. The lightness L * signal 012 and the a * b * signal 013 are input to the buffer, and the L * a * b * value of each pixel of the image is held. The lightness L * signal 012 is also input to the lightness distribution survey unit 021. The lightness distribution examining unit 021 calculates the average value or mode value of the lightness L * signal value of each pixel, and sends the value to the saturation coefficient determining unit 003 as the reference lightness Lp022.

  The saturation coefficient determination unit 003 sequentially reads the lightness L * 012 of each pixel from the buffer, determines the saturation coefficient g014 of the pixel from the reference lightness Lp022 and the lightness L * 012 of each pixel, and colors the information. It is sent to the degree coefficient application unit 004. The saturation coefficient application unit 004 reads the a * b * value 013 from the buffer in synchronization with the saturation coefficient determination unit 003, and multiplies the corresponding saturation coefficient g014. If the background has very bright or dark parts, the average and mode of the entire image are more susceptible to the background than the main subject. Therefore, assuming that the main subject is generally near the center of the screen, only the pixels in the area near the center of the screen may be used for calculation to obtain an average value or a mode value.

  In the sixth embodiment, the light / dark signal adjustment unit 007 described with reference to FIG. 3 may be provided. The configuration diagram of FIG. 16 is a configuration example when the result of the brightness adjustment unit 007 is reflected in the determination of the saturation coefficient. The configuration diagram of FIG. 17 is an example in the case where the result of the brightness adjustment unit 007 is not reflected in the determination of the saturation coefficient. In these examples, L * ′ adjusted by the light / dark adjustment unit 007 is used as an input to the color space conversion unit 005 in any case.

  In the above-described embodiments, the configuration is such that processing is performed by hardware, but it is not necessary to be limited to this. For example, it is possible to record the captured signal as raw data as raw data, and record various setting information at the time of shooting from the control unit 121 as header information of the image, and separately process the software (program). .

  FIG. 9 is a flowchart showing an example of a procedure related to software processing corresponding to the second embodiment. This flowchart will be described. In Step 1, read header information such as image signals and various settings. In Step 2, an RGB three-plate image is generated by known interpolation. In Step 3, obtain the white balance coefficient from the header information and perform white balance processing. Perform color space conversion in Step 4 and calculate L * a * b * from RGB. In Step 5, the L * value is adjusted according to the setting of a predetermined gradation conversion curve.

  In Step 6, the shooting scene information and ISO sensitivity information are obtained from the header information, the LUT and the arithmetic expression are selected, and the saturation coefficient is determined according to the adjusted L * value. In step 7, the saturation coefficient is applied to each of the color signals a * and b *. Color space conversion is performed in Step 8, and the L * a * b * signal is returned to the RGB signal. In Step 9, it is determined whether the processing has been completed for all pixels. When the processing is not completed, the loop processing of Step 4 to Step 8 is repeated, and when the processing is completed, the image signal is output at Step 10 and the processing is terminated.

  The flowchart of FIG. 9 can correspond to a program for executing the operation of the color conversion module described in FIG. 1 and an image processing system using this color conversion module, omitting the processing of Step 2, Step 3, and Step 5. . In this case, the computer reads the image signal (Step 1), performs the first color space conversion on the image signal (Step 4), and the color space converted first image signal (Step 4). L *) determining a saturation coefficient (Step 6), applying the determined saturation coefficient to the color space-converted second image signal (a * b *), The color adjustment is realized by a program by executing a procedure (Step 8) for performing the second color space conversion on the first image signal (L *) and the second image signal (a * b *). is there.

  Further, the flowchart of FIG. 9 shows a procedure for further performing pre-processing such as interpolation (Step 2) and white balance processing (Step 3) on the computer, and the first image signal (L *) subjected to color space conversion. And a procedure for adding and executing a procedure (Step 5) for adjusting the light / dark signal. This program executes the operation of the imaging apparatus shown in FIG.

  FIG. 10 is a flowchart corresponding to the fifth embodiment, showing an example of a procedure related to software processing when the saturation coefficients for two color signals are different. Steps 1 to 5 and Steps 8 to 10 are the same as those in FIG. In Step 11 and Step 12, the shooting scene information and ISO sensitivity information are obtained from the header information read in Step 1, and the LUT and arithmetic expression are selected, and the first saturation coefficient and the second are selected according to the L * value adjusted in Step 5. Determine the saturation coefficient of. Step 13 applies the first saturation coefficient to the color signal a *, and Step 14 applies the second saturation coefficient to the color signal b *.

  The flowchart of FIG. 10 can correspond to a program for executing the operation of the color conversion module shown in FIG. 5 and an image processing system using this color conversion module, omitting the processing of Step 2 and Step 3 and Step 5. In this case, the computer reads the image signal (Step 1), performs the first color space conversion on the image signal (Step 4), and the color space converted first image signal (Step 4). L *) to determine a first saturation coefficient (Step 11), a procedure to determine a second saturation coefficient from the color space-converted first image signal (L *) (Step 12), A step (Step 13) of applying the determined first saturation coefficient to the color image-converted second image signal (a *), and the determined second saturation coefficient to the color The procedure (Step 14) applied to the spatially transformed third image signal (b *) and the second to the first image signal to the third image signal (L * a * b *). The color adjustment is realized by a program by executing a procedure (Step 8) for performing color space conversion.

  Further, the flowchart of FIG. 10 shows a procedure for further performing pre-processing such as interpolation (Step 2) and white balance processing (Step 3) on the computer and the first image signal (L *) subjected to color space conversion. The program corresponds to a program for performing color adjustment by adding and executing a procedure (Step 5) for performing light / dark signal adjustment. This program is to execute the operation of the image pickup apparatus shown in FIG.

  FIG. 12 is a flowchart showing a software processing procedure corresponding to the sixth embodiment. In step 21, an RGB image signal is read. In step 22, the first color space conversion is performed to obtain an L * a * b * signal. In step 23, it is determined whether processing has been completed for all pixels. If this determination result is not complete for all pixels, the process of Step 22 is repeated. If the color conversion has been completed for all the pixels, in Step 24, the average value or mode value of the lightness L * value is calculated for the entire image or pixels in a specific range, and the value is set as the reference lightness.

  In Step 25, a saturation coefficient is calculated from the lightness L * of each pixel and the reference lightness calculated in Step23. In Step 26, a saturation coefficient is applied to each of the color signals a * and b * of each pixel. In Step 27, the second color space conversion is performed, and the L * a * b * signal is returned to the RGB signal. In Step 28, it is determined whether or not the processing has been completed for all pixels. If not, the loop processing from Step 25 to Step 27 is repeated. When the process is completed, the image signal is output at Step 29 and the process is terminated.

  The flowchart of FIG. 12 shows a procedure for reading an image signal into a computer (Step 21), a procedure for performing a first color space conversion on the image signal (Step 22), and the first color space conversion for all pixels. A procedure for determining whether or not the processing has been completed (Step 23), a procedure for calculating a reference lightness for the first image signal (L *) subjected to the first color space conversion (Step 24), and the reference lightness A procedure (Step 25) for determining a saturation coefficient for the first image signal (L *), and the determined saturation coefficient for the second image signal subjected to the first color space conversion. This corresponds to a program for executing a procedure to apply and a procedure (Step 27) of performing a second color space conversion on the first image signal and the second image signal (a * b *).

  This program corresponds to the color conversion module described in FIG. 11 and a program for executing the operation of the image processing system using this color conversion module. If a light / dark signal adjustment unit is provided, a procedure for performing light / dark adjustment after Step 22 or Step 23 may be executed, and the result may be reflected in the coefficient determination in Step 25. When the result of the brightness adjustment unit is not reflected in the coefficient determination of Step 25, the procedure for performing the brightness adjustment is executed between Step 22 and Step 27.

  In all the above embodiments, L * a * b * is used as the color space for light and darkness and color adjustment, but other than L * u * v *, YCbCr, etc. Other color spaces may be used. In the first to third embodiments, a color space that directly represents lightness, saturation, and hue, such as HCV, may be used. In that case, the saturation coefficient is applied only to the saturation, not to the hue. Further, the saturation coefficient application unit 004 performs saturation adjustment by simply multiplying the coefficient, but the application method of the coefficient is not limited to multiplication, and may be applied in the form of addition / subtraction or a higher-order function.

As described above, according to the present invention allows a favorable image quality adjustment on the digital image, the color adjustment module Contact and imaging apparatus, and it is possible to provide a program for realizing the color adjustment.

1 is a configuration diagram illustrating an embodiment of a color conversion module and an image processing system of the present invention. It is a characteristic view in an embodiment of the present invention. It is a block diagram which shows embodiment of the imaging device of this invention. It is a characteristic view in an embodiment of the present invention. It is a block diagram which shows other embodiment of the color conversion module of this invention, and an image processing system. It is a characteristic view in an embodiment of the present invention. It is a block diagram which shows other embodiment of the imaging device of this invention. It is a characteristic view in an embodiment of the present invention. It is a flowchart which shows the process sequence of this invention. It is a flowchart which shows the other process sequence of this invention. It is a block diagram which shows other embodiment of the color conversion module of this invention, and an image processing system. It is a flowchart which shows the other process sequence of this invention. It is a block diagram which shows other embodiment of the image processing system of this invention. It is a block diagram which shows other embodiment of the image processing system of this invention. It is a block diagram which shows other embodiment of the image processing system of this invention. It is a block diagram which shows other embodiment of the image processing system of this invention. It is a block diagram which shows other embodiment of the image processing system of this invention.

Explanation of symbols

  001 ... Image input unit, 002 ... First color space conversion unit, 003 ... Saturation coefficient determination unit, 004 ... Saturation coefficient application unit, 005 ... Second color space conversion 006: Image output unit, 021: Lightness distribution survey unit, 101 ... Optical system, 102 ... Imaging device, 103 ... Initial signal processing unit, 104 ... Interpolation processing unit, 105... White balance (WB) processing unit 106... First color space conversion unit 107. Light / dark signal adjustment unit 108 .. Post-processing unit 109. ... Control unit, 122 ... External I / F, 201 ... Saturation coefficient determination unit, 202 ... Saturation coefficient application unit, 203 ... First application unit, 204 ... No. 2 application sections,

Claims (7)

A light / dark component signal and a color component signal of an image are input, a coefficient corresponding to the light / dark component signal of the image is applied to the color component signal, the color component signal value is changed, and the changed color component signal A color adjustment module that outputs
Comprising a light / dark distribution investigation unit for setting a reference value based on a statistic of the light / dark component signal value within a predetermined range in the image, and determining the coefficient based on the light / dark component signal value and the reference value;
The relationship between the coefficient and the light / dark component signal value is characterized in that the coefficient is small near the upper and lower limits of the light / dark component signal value and large when the light / dark component signal value is an intermediate value. Color adjustment module. The imaging apparatus according to claim 1 , wherein the coefficient is increased as the light / dark component signal value is closer to the reference value. An electronic imaging unit, a pre-processing unit that processes a signal from the electronic imaging unit to generate a primary color or complementary color image signal, and a primary color or complementary color image signal supplied from the pre-processing unit, A first color space conversion unit that converts a light / dark component signal and a color component signal, and a color that changes a color component signal value by applying a coefficient corresponding to the light / dark component signal of the image to the color component signal An adjustment unit, a second color space conversion unit that integrates the light / dark component signal and the changed color component signal and reconverts them into a primary color or complementary color image signal; and a primary color or complementary color image signal A post-processing unit that performs processing according to the output form and outputs the result,
An imaging apparatus that holds setting information at the time of imaging, and changes a relationship between the light / dark component signal value and the coefficient according to the setting information at the time of imaging. Comprising a light and dark signal adjustment unit for adjusting the brightness component signal, the color adjustment unit according to claim 3, wherein applying the coefficient corresponding to the output of the light and dark signal adjusting unit to the color component signals Imaging device. A light / dark component signal of the image and a plurality of color component signals are input, and a coefficient corresponding to the light / dark component signal is applied to each signal related to the color to change each color component signal value, and the changed color component signal Is a color adjustment module that outputs a relationship between the coefficient and the light / dark component signal for each color component signal, and the relationship between the coefficient and the light / dark component signal is a region where the light / dark component signal value is large. Then, in a region where the first coefficient for the first signal is larger than the second coefficient for the second signal among the plurality of signals related to the color and the light and dark component signal value is small, the second coefficient is the first coefficient. A color adjustment module that is larger . An electronic imaging unit, a pre-processing unit that processes a signal from the electronic imaging unit to generate a primary color or complementary color image signal, and a primary color or complementary color image signal supplied from the pre-processing unit, A first color space conversion unit that converts a light / dark component signal and a plurality of color component signals, and applying a coefficient corresponding to the light / dark component signal of the image for each of the plurality of color component signals, A color adjustment unit that changes each color component signal value, a second color space conversion unit that integrates the light / dark component signal and the changed color component signal and reconverts them into an image signal of a primary color system or a complementary color system, the image signals of the primary color or complementary color system, comprising a post-processing unit for processing performed by outputting the combined output form, the relationship between the brightness component signal and the coefficient is different with each of the plurality of color component signals , Holds the setting information at the time of shooting, and the shooting Imaging and wherein said changing the relationship between the coefficient and the brightness component signal corresponding to each color component signals in accordance with the setting information. The computer, the procedure of reading the image signal, a step of generating a first brightness component signal and the color component signals I line color space conversion on the image signal for all pixels of the first color space conversion a procedure of calculating a procedure for determining whether the termination, relative brightness component signal based on the image signal of the first color space conversion to generate I line, the reference brightness based on the statistics of the brightness component signal A step of determining the saturation coefficient according to the reference lightness; a step of applying the determined saturation coefficient to the color component signal; and a second step for the light / dark component signal and the color component signal . A program for realizing color adjustment that executes the procedure for color space conversion.

Images