JP3564333B2 - Color correction device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color correction device for a color video signal for realizing a high level of color reproducibility particularly required for image pickup devices for broadcasting and business use.
[0002]
[Prior art]
As a conventional color correction device for color video signals, for example, there is a six-color independent color tone correction method. This six-color independent correction method is applicable to six colors of R (red), Ma (magenta), B (blue), Cy (cyan), G (green), and Ye (yellow) without changing the white balance. Each of them independently corrects saturation (color saturation) and chromaticity (hue). As a specific example, there is, for example, Japanese Patent Laid-Open No. 3-272294.
[0003]
Here, a conventional example of a six-color independent color tone correction method will be described with reference to FIG. In the figure, reference numerals 56, 57 and 58 denote arithmetic / comparators, 59 denotes a hue area determination circuit, 60 denotes a primary color component amount and complementary color component amount calculation circuit, 61 denotes a constant selection circuit, 62 and 63 denote multipliers, and 64 and 65 Is a −1 multiplier, 66 is a data selection and addition circuit, and 67, 68 and 69 are adders.
[0004]
The operation of the conventional color correction apparatus configured as described above will be described with reference to FIGS.
[0005]
First, the arithmetic / comparators 56, 57, and 58 calculate the color difference signals RG, RB, and GB from the input video signals R, G, and B, and compare the magnitudes thereof. And the primary color component amount and complementary color component amount calculation circuit 60.
Therefore, the hue area determination circuit 59 first determines the hue area as shown in FIG. 16 based on the calculation results of the calculators / comparators 56, 57, and 58. FIG. 17 is a conceptual diagram of this hue area, which is divided into six hue areas based on a straight line from the center point toward each color direction.
[0006]
The primary color component amount and complementary color component amount calculation circuit 60 compares the levels of the signals R, G, and B, and determines the maximum level, intermediate level, and minimum level as shown in FIG. Then, in the process of this comparison and determination, the level difference between the maximum level and the intermediate level is obtained and used as the primary color component amount, and further the level difference between the intermediate level and the minimum level is obtained and used as the complementary color component amount. Here, the maximum level color corresponds to the primary color, and the minimum level component corresponds to the white component. Then, the complementary color can be determined from the information of the maximum level color and the minimum level color. As a result, as shown in FIG. 16, the primary color component and the complementary color component can be determined.
[0007]
In the example shown in FIG. 18, since the maximum level is R and the intermediate level is G, the primary color component is R, and the complementary color component is Ye (yellow) between hues of R and G. The primary color component amount is RG, the complementary color component amount is GB, and the level of the minimum level B is the white component amount.
[0008]
The hue area determination result by the hue area determination circuit 59 is supplied to the constant selection circuit 61, and a specific gain constant is selected according to the determination result, which is supplied to the multipliers 62 and 63. Correction is performed by multiplying the calculated primary color component amount and complementary color component amount. Therefore, specific gain constants corresponding to the respective hue regions from region 1 to region 6 are set in the constant selection circuit 61 in advance.
[0009]
The primary color component amount and the complementary color component amount multiplied by the gain constants by the multipliers 62 and 63 are added to the data selection circuit 66 for selecting addition / subtraction and connection selection for the video signals R, G, B, on the one hand. Directly supplied on the other hand via complements (-1 multipliers) 64 and 65, respectively. Then, after the addition destination is selected by the data selection / addition circuit 66, it is supplied to the adders 67, 68, 69 and added to the video signals R, G, B.
[0010]
Therefore, when correcting the tone of the signal R, for example, in the case of correction in the saturation direction, the primary color component amount RG is multiplied by a specific constant Kr and then added to the video signal R. At this time, if the ratio of the constant Kr is in the range of −1 to 1 times, the level difference between the intermediate level and the minimum level (complementary color component amount) and the minimum level amount (white component amount) are also obtained by this correction. It does not change.
[0011]
When correcting the saturation direction of the signal Ye, the complementary color component amount GB is multiplied by a specific constant Ky and then added to R and G, respectively. Also at this time, if the ratio of the constant Ky is in the range of −1 to 1 times, the level difference between the maximum level and the intermediate level (primary color component amount) and the minimum level amount (white component amount) are also obtained by this correction. Does not change.
[0012]
Therefore, in this case, the saturation directions of the primary color R and the complementary color Ye can be independently corrected while maintaining the white balance by operating the constants Kr and Ky. The same applies to other hues. In the above six-color independent tone correction method, the chromaticity direction can be corrected independently.
[0013]
[Problems to be solved by the invention]
However, in the above-described conventional technique, although it works effectively for colors close to six colors of R, Ma, B, Cy, G, and Ye, a sufficient operation is not performed for those intermediate colors. For example, correction of skin color, which is an intermediate hue between R and Ye, tends to remain in human memory, so that a subtle difference in color tone is likely to be recognized. Therefore, accurate color tone correction is necessary in advance to obtain a skin-like color, but since it is an intermediate color, fine correction is difficult with the prior art, and correct skin color correction cannot be performed.
[0014]
FIG. 19 shows the gain in the saturation direction of R and Ye when the skin color correction is performed in the prior art. As can be seen from FIG. 19, if the saturation direction gain of R and Ye is increased, the saturation of the skin color is shown. Although it is possible to increase the gain in the degree direction, it cannot be used in practice because it greatly affects the color tone of R and Ye.
[0015]
Further, a technique has been proposed in which the above-described conventional technique is developed to further divide the six colors and correct the intermediate colors by using the six color reference axes and the auxiliary reference axes therebetween (for example, JP-A-9-247701). Means for disassembling the color to be corrected into a reference axis that sandwiches the color to be corrected and an auxiliary reference axis are necessary, and the circuit scale has increased, making it difficult to easily correct.
[0016]
Also, for broadcast and commercial use, the images of a large number of television cameras are often switched and used by a switcher, and it is very important to make the colors of each camera the same. Further, as with the sharpness of brightness, it is important to adjust the color equally to eliminate the unpleasant feeling of the switching video such as the sharpness at the time of high saturation, but it is difficult to cope with the conventional technology.
[0017]
As described above, the conventional color correction apparatus has the above-described problems.
[0018]
In view of this point, the present invention is divided into hues that are divided into fine colors such as not only the reference colors but also their intermediate colors, and further the intermediate colors of the reference colors and intermediate colors with a simple configuration without a significant increase in circuit scale. The purpose is to provide a color correction device that can independently perform color correction. Furthermore, it is possible to easily unify the colors of multiple television cameras using this color correction device, and to cope with sharpness at high saturation. The purpose is to be able to reduce the impact.
[0019]
[Means for Solving the Problems]
In order to solve this problem, the present invention generates a plurality of hue axes including axes of three primary color components and having an axis orthogonal to each of the axes, and sets the color for each hue region divided by these hue axes. A color correction device that performs correction, generates a plurality of hue axis signals by a hue axis generation circuit, identifies a hue area from a plurality of hue axis signals by a hue area identification circuit, and corrects the identified hue area In this case, the hue axis selection circuit selects two axes of the first and second hue axis signals orthogonal to the two hue axes sandwiching the hue region, and the first and second gain variable means respectively The gains of the signals on the first and second hue axes are controlled by the saturation correction gain in the correction area. Further, the output signal of the first gain variable means is converted into the ratio of the red, green, and blue components of the axes that are not orthogonal to the first hue axis, out of the two axes that sandwich the color correction area. Similarly, the output signal of the second gain varying means is converted into the ratio of the red, green, and blue components of the axes that are not orthogonal to the second hue axis among the two axes that sandwich the color correction region. The gain is converted by the second gain converting means, and the signals in the R axis direction, the G axis direction, and the B axis direction that have been subjected to the gain conversion are added to the corresponding input signals, thereby correcting the saturation direction. It is realized.
[0020]
This makes it possible to independently correct the saturation of each hue region, and to finely correct the saturation of intermediate colors by finely dividing the hue region.
[0021]
Further, in the present invention, in order to correct the chromaticity, the output signal of the first gain varying means is set to the axis that is not orthogonal to the first hue axis among the two axes that sandwich the area where the color correction is performed. The gain is converted by the first gain conversion means for converting the gain into the ratio of the red, green and blue components that move the hue in the vertical direction, and the output signal of the second gain variable means is similarly converted into an area for color correction. Of the two sandwiched axes, gain conversion is performed by a second gain converting means that converts the gain to a ratio of red, green, and blue components that moves the hue in a direction perpendicular to the axis that is not orthogonal to the second hue axis. These gain-converted signals in the R-axis direction, G-axis direction, and B-axis direction are added to the corresponding input signals, thereby realizing chromaticity correction.
[0022]
As a result, the chromaticity of each hue region can be independently corrected, and the chromaticity of the intermediate color can be finely corrected by finely dividing the hue region.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 of the present invention generates a plurality of hue axes including axes of the three primary color signals of red, green, and blue on the hue coordinates and having an axis orthogonal to each axis, A color correction apparatus that performs color correction for each hue region divided by these hue axes, and includes a hue axis generation circuit that generates a plurality of hue axis signals from an input video signal, and a plurality of hue axis signals Select a hue area identification circuit for identifying the corresponding hue area, and signals of the first and second hue axes that are orthogonal to the two hue axes sandwiching the hue area that performs color correction from the signals of the plurality of hue axes For the output signal of the hue axis selection circuit, the first and second gain variable means for varying the gain of the signals of the first and second hue axes, and the output signal of the first gain variable means, Of the two hue axes sandwiching the area for color correction, An area for performing color correction on the output signal of the first gain converting means for converting the gain into the ratio of the red, green, and blue components of the axis that is not orthogonal to the one hue axis and the second gain variable means. A second gain converting means for converting the gain into a ratio of red, green, and blue components of an axis that is not orthogonal to the second hue axis, and an R axis from each of the gain converting means An adder circuit for adding the respective outputs of the direction, the G-axis direction, and the B-axis direction to the corresponding three primary color signals of the input video signal, and the hue axis selection circuit based on an identification signal from the hue area identification circuit And a control circuit that controls the first and second gain variable means and the first and second gain conversion means according to each hue area and independently corrects the saturation of each hue area. Yes, two selected axes (first and second hue axes These signals have the effect of varying the gains in the two axial directions sandwiching each correction area, and the saturation of each hue area can be corrected independently, By finely dividing, it is possible to finely correct the saturation of intermediate colors.
[0024]
Further, the invention according to claim 2 generates a plurality of hue axes including axes of the three primary color signals of red, green, and blue on the hue coordinates and having axes orthogonal to the respective axes. A color correction device that performs color correction for each hue region divided by a hue axis, and that corresponds to a hue axis generation circuit that generates a signal of the plurality of hue axes from an input video signal and a signal of the plurality of hue axes Selecting a hue area identification circuit for identifying the hue area to be performed, and signals of the first and second hue axes orthogonal to two hue axes sandwiching the hue area for color correction from the signals of the plurality of hue axes For the hue axis selection circuit, the first and second gain variable means for changing the gains of the first and second hue axis signals, and the output signal of the first gain variable means, Of the two hue axes sandwiching the region to be corrected, the first First gain converting means for converting the gain to a ratio of red, green and blue components that move the hue in a direction perpendicular to the axis that is not orthogonal to the hue axis of the first color, and an output signal of the second gain variable means The ratio of the red, green, and blue components that move the hue in the direction perpendicular to the axis that is not orthogonal to the second hue axis, out of the two hue axes that sandwich the region where the color correction is performed. A second gain conversion means for converting the gain, and an addition for adding the respective outputs in the R-axis direction, the G-axis direction, and the B-axis direction from the respective gain conversion means to the corresponding three primary color signals of the input video signal Circuit, a gain positive / negative determination circuit for determining the positive / negative of each gain of the first and second gain variable means, an identification signal from the hue area identification circuit, and a determination signal of the gain positive / negative determination circuit, Hue axis selection circuit A control circuit that controls the first and second gain variable means and the first and second gain conversion means according to each hue region and independently corrects the chromaticity of each hue region; The signals of the selected two axes (first and second hue axes) are used as correction signals, and these signals have the effect of varying the gain in the vertical direction with respect to the two axes sandwiching each correction region. The chromaticity of each hue region can be independently corrected, and by finely dividing the hue region, the chromaticity of the intermediate color can be finely corrected.
[0025]
According to a third aspect of the present invention, in the first aspect of the present invention, in the first and second gain variable means, saturation discontinuity does not occur on the hue axis dividing each hue region. In addition, the correction gains before and after the hue axis are set to the same gain setting, so that it is possible to avoid a step in the saturation correction at the boundary of the hue region.
[0026]
According to a fourth aspect of the present invention, in the second aspect of the present invention, in the first and second gain varying means, chromaticity discontinuity does not occur on the hue axis dividing each hue region. In addition, the correction gains before and after the hue axis are set to the same gain setting, so that it is possible to avoid a step in the chromaticity correction at the boundary of the hue region.
[0027]
Further, the invention according to claim 5 includes at least one of the color correction device according to claim 1 or 3 and the color correction device according to claim 2 or 4 and the three primary color signal components of red, green, and blue. A reference color generation circuit for generating a reference color signal configured; and an output signal of the reference color generation circuit and a video signal composed of three primary color signal components of red, green, and blue obtained from an actual imaging subject. In the case of an output signal of the reference color generation circuit based on an output signal of the gain conversion means of the color correction device to which the output signal from the switching circuit is input and the output signal from the switching circuit is input by switching and outputting to the color correction device A correction amount difference calculating circuit for calculating a difference in at least one of saturation and chromaticity between the case of a video signal of an actual imaging subject and an output signal of the correction amount difference calculating circuit and a predetermined base A comparison circuit that compares the level signal and provides an output corresponding to the difference, and controls the correction gain of the color correction device based on the output of the comparison circuit. The correction amount (gain) of at least one of the degrees can be set on the basis of the signal of the reference level, so that the saturation is obtained in a plurality of apparatuses including the color correction apparatus of the present invention, for example, a plurality of television cameras. And at least one of the chromaticity, that is, the color tone can be unified.
[0028]
According to a sixth aspect of the present invention, at least one of the color correction device according to the first or third aspect and the color correction device according to the second or fourth aspect and the color correction output from the color correction device are corrected. A chroma detail circuit that generates a color difference signal based on the received signal, extracts a high-frequency component of the color difference signal, and performs frequency correction in a high-saturation image, and at least one of saturation and chromaticity in the color correction device A gain control circuit that controls the gain of the chroma detail circuit based on a gain constant that determines the correction amount of the chroma detail circuit and a chroma detail gain constant that determines the correction amount of the chroma detail circuit. Even when at least one of degree and chromaticity is corrected, the chroma detail gain that corrects sharpness is adjusted appropriately. Come, it is possible to suppress the effect of the sharp sense of high saturation image. According to a seventh aspect of the present invention, in the sixth aspect of the present invention, the gain control circuit is configured to decrease the chroma detail gain when the chroma gain constant is positive and increase the gain when the chroma gain constant is negative. This makes it possible to perform chroma detail correction similar to the case where saturation correction is not performed.
[0029]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0030]
(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a color correction apparatus according to Embodiment 1 of the present invention.
[0031]
The color correction apparatus according to this embodiment generates a plurality of hue axes including axes of the three primary color signals of red, green, and blue on the hue coordinates and having axes orthogonal to the respective axes. In FIG. 1, reference numeral 1 denotes a hue axis generation circuit that generates a plurality of hue axis signals from an input video signal composed of three primary color signal components. Hue area identification circuit 3 for identifying the hue area divided from the output signal of the hue axis generation circuit 1, two axes orthogonal to the two axes sandwiching the area for color correction from the hue axis signal of the hue axis generation circuit 1 And a hue axis selection circuit that outputs the hue axis ODD as the first hue axis and the hue axis EVEN as the second hue axis, and 4 and 5 are the hue axis ODD and hue output from the hue axis selection circuit 3, respectively. Vary the signal gain of the axis EVEN The in-control circuits ODD and EVEN 6 and 7 are gain select circuits ODD and EVEN for switching the gain constants to the gain control circuits ODD4 and EVEN5. The gain control circuits ODD and EVEN4 and 5 and the gain select circuits ODD and EVEN6 and 7 Thus, first and second gain varying means for varying the gains of the signals of the first and second hue axes are configured.
[0032]
8, 9, and 10 are ratios of red, green, and blue components of axes that are not orthogonal to the hue axis ODD that is the first hue axis of the two axes that perform color correction with respect to the output signal of the gain control circuit ODD4. R-axis direction, G-axis direction, and B-axis direction gain conversion circuits that perform gain conversion into the same, and 11, 12 and 13 are the second hues of the two axes that perform color correction on the output signal of the gain control circuit EVEN5. R-axis direction, G-axis direction, and B-axis direction gain conversion circuits that perform gain conversion to the ratio of the red, green, and blue components of the axis that is not orthogonal to the hue axis EVEN, which is the axis, the R-axis direction, the G-axis direction, B-axis direction gain conversion circuits 8, 9, and 10 constitute first gain conversion means, and R-axis direction, G-axis direction, and B-axis direction gain conversion circuits 11, 12, and 13 constitute second gain conversion means. Is done.
[0033]
Reference numeral 14 denotes a control signal generation circuit as a control circuit that outputs a control signal to each circuit in accordance with an output signal of the hue area identification circuit 2, and reference numerals 15, 16, and 17 denote input three primary color signals and R axis direction, G axis direction, and B axis direction. This is an adder for adding correction signals output from the gain conversion circuits ODD8 to ODD8 and EVEN11 to 13.
[0034]
The operation of the color correction apparatus according to Embodiment 1 configured as described above will be described below with reference to FIGS. In the following description, the areas (1), (2), (3)... In FIGS.
[0035]
FIG. 2 is a conceptual diagram when the hue coordinates are divided into 12 with six types of hue axes f1 to f6, and FIG. 3 is a hue area discrimination indicating each area of the divided hue areas and the positive / negative correspondence of the hue axis signal. FIG. 4 is an explanatory diagram for explaining an example of color correction, and FIG. 5 is an explanatory diagram for explaining how to select a gain in the gain selection circuits 6 and 7 and how to apply the gain.
[0036]
As shown in FIG. 2, the hue axis generation circuit 1 generates six hue axes f1 to f6 that divide the hue coordinates by 30 degrees and divide the hue coordinates into 12 hue regions. That is, their hue axes are given by the following arithmetic expression from the input three primary color signals of R, G and B.
[0037]
f1 = BG
f2 = 2G- (R + B)
f3 = GR
f4 = 2R− (G + B)
f5 = R−B
f6 = 2B- (R + G)
The hue axes f <b> 1 to f <b> 6 created by the hue axis generation circuit 1 are input to the hue area identification circuit 2 and the hue axis selection circuit 3.
[0038]
As shown in FIG. 3, the hue area identification circuit 2 identifies each hue area based on the sign of each hue axis corresponding to each of the areas 1 to 12 and identifies it to the control signal generation circuit 14. Output a signal. The control signal generation circuit 14 sends the control signal to the hue axis selection circuit 3, the gain selection circuit ODD6 and the gain selection circuit EVEN7, the R axis direction gain conversion circuit ODD8, the G axis direction gain conversion circuit ODD9, according to the input identification signal. The data is output to the B-axis direction gain conversion circuit ODD10, the R-axis direction gain conversion circuit EVEN11, the G-axis direction gain conversion circuit EVEN12, and the B-axis direction gain conversion circuit EVEN13.
[0039]
The hue axis selection circuit 3 selects and outputs two axes orthogonal to the respective axes with respect to the two axes sandwiching the color correction region, based on the output signal of the control signal generation circuit 4.
[0040]
For example, when correcting the region 1 as shown in FIG. 4, the two axes sandwiching the region 1 are f1 and f2, and the two axes orthogonal to f1 and f2 are f4 and f5. The hue axis f5 is selected as the first hue axis ODD and f4 is selected as the second hue axis EVEN and output.
[0041]
Thereafter, the signal of the hue axis ODD is multiplied by a predetermined gain constant by the gain control circuit 4 and the gain signal output from the gain selection circuit ODD6, and the R axis direction gain conversion circuit ODD8, G axis direction gain conversion circuit ODD9, and B axis It is output to the direction gain conversion circuit ODD10. Each gain conversion circuit ODD converts an input hue axis ODD signal into R, G, and B of the hue axis f1 (that is, an axis that is not orthogonal to the first hue axis ODD among the two axes sandwiching the hue region 1). The gain is converted into a ratio and output to the corresponding adder circuits 15, 16, and 17. In this example, since f1 is R: G: B = 1: 0: 2, the gain is converted to a ratio of R: G: B = 1: 0: 2 and output. If this signal is added, the gain in the f1 axis upward direction is varied.
[0042]
Similarly, the signal of the hue axis EVEN is multiplied by a predetermined gain constant by the gain signal output from the gain selection circuit EVEN7 by the gain control circuit 5, and the R-axis direction gain conversion circuit EVEN11, G-axis direction gain conversion circuit EVEN12, B It is output to the axial gain conversion circuit EVEN13. Each gain conversion circuit EVEN outputs an input signal of the hue axis EVEN to R, G, and B of the hue axis f2 (that is, an axis that is not orthogonal to the second hue axis EVEN among the two axes sandwiching the hue region 1). The gain is converted into a ratio and output to the corresponding adders 15, 16, and 17. In this example, since f2 is R: G: B = 1: 0: 1, the gain is converted to a ratio of R: G: B = 1: 0: 1 and output. If this signal is added, the gain on the f2 axis is changed.
[0043]
Each R-axis direction gain conversion circuit ODD8, G-axis direction gain conversion circuit ODD9, B-axis direction gain conversion circuit ODD10, R-axis direction gain conversion circuit EVEN11, G-axis direction gain conversion circuit EVEN12, B-axis direction gain conversion circuit EVEN13 The gain conversion ratio is set by the control signal generation circuit 14 to the ratio corresponding to the region 1.
[0044]
In this way, the signal components of the hue axis ODD (f5) and the hue axis EVEN (f4) are converted so as to change the gains on the two axes f1 and f2 across the hue region 1, and the adders 15, By adding to the input three primary color signals at 16 and 17, the saturation of the hue region 1 is varied.
[0045]
Here, how to select the gain of the gain select circuit ODD6 and the gain select circuit EVEN7 will be described with reference to FIG.
[0046]
FIG. 5 shows an example in which saturation correction is performed for hue regions 1 and 2. As described above, for the hue region 1, the hue axis ODD output from the hue axis selection circuit 3 is f5, and the hue axis EVEN is f4. Similarly, for the hue area 2, f5 is selected for the first hue axis ODD and f6 is selected for the second hue axis EVEN. The gain select circuit ODD6 selects the gain constant AG1 in the region 1 and the gain constant AG3 in the region 2 by the control signal generation circuit 14. Further, the gain select circuit EVEN7 selects the gain constant AG2 in the region 1 and the gain constant AG2 in the region 2. That is, the correction gain in the vicinity of the boundary of the hue area is set to the same constant to prevent a correction step from appearing at the boundary. That is, AG1 to AG6 are selected as gain constants corresponding to the hue axes f1 to f6 in the regions 1 to 6, and AG7 to AG12 are selected as gain constants corresponding to the hue axes f1 to f6 in the regions 7 to 12.
[0047]
Further, since the hue axis f5 is a signal orthogonal to the hue axis f2, the hue axes f1 and f3 have the maximum level and the hue axis f2 has the minimum (0) level. Therefore, the correction by the hue axis f5 has no effect on the hue axis f2. Conversely, since the hue axis f4 is a signal orthogonal to the hue axis f1, the hue axis f2 has the maximum level and the hue axis f1 has the minimum level, and the correction by the hue axis f4 has no effect on the hue axis f1. Furthermore, since the hue axis f6 is a signal orthogonal to the hue axis f3, the hue axis f2 has the maximum level and the hue axis f3 has the minimum (0) level, and the correction by the hue axis f6 is not performed on the hue axis f3. No effect.
[0048]
As shown in FIG. 5, the amplitudes of the correction gains on the axes of the hue axes f1, f2, and f3 are illustrated as a to c in the figure, and by varying the gain constants AG1, AG2, and AG3, respectively, The saturation in each region can be varied separately by adding a and b in the hue region 1 and by adding b and c in the hue region 2. The same applies to the other hue regions.
[0049]
As described above, according to the first embodiment of the present invention, not only colors close to six colors of R, Ma, B, Cy, G, and Ye but also an intermediate color between these two colors can be effectively acted. Saturation correction can be performed independently. In the present embodiment, since the hue region is equally divided into 12, the ratio of the three primary color signals on each axis is R: G: B = 0: 0: 1, R: G: B = 1. 0: 2, R: G: B = 1: 0: 1, R: G: B = 2: 0: 1, R: G: B = 1: 0: 0, etc. (for example, hue regions 12, 1, 2, 3. The same applies to the other areas). Since the ratio is simple, each R axis direction gain conversion circuit ODD8, G axis direction gain conversion circuit ODD9, B axis direction gain conversion circuit ODD10, R axis direction gain conversion circuit EVEN11, G axis The direction gain conversion circuit EVEN12 and the B-axis direction gain conversion circuit EVEN13 can be realized with a simple circuit by bit shift of digital data without using a multiplier.
[0050]
Further, unlike the conventional example described above, it is not necessary to have a means for separating the reference color and the auxiliary reference axis that sandwich the color to be corrected, and it can be realized with a relatively simple circuit configuration.
[0051]
Although not specifically described, rewriting and setting of the values of the gain constants AG1 to AG12 can be appropriately realized by means such as a microcomputer (not shown). (Embodiment 2)
FIG. 6 is a block diagram showing the configuration of the color correction apparatus according to the second embodiment of the present invention. In FIG. 6, 1 is a hue axis generation circuit, 2 is a hue area identification circuit, 3 is a hue axis selection circuit that selects two axes of the hue axes ODD and EVEN as the first and second hue axes, and 4 and 5 are gains. The control circuits ODD and EVEN, 6 and 7 switch the gain constants to the gain control circuits ODD4 and EVEN5 and output them. The gain select circuits ODD and EVEN, 15, 16, and 17 are adders, and 18, 19, 20, 21, 22, and 23. Is a gain conversion circuit for the R-axis direction, G-axis direction, and B-axis direction, 25 is a gain positive / negative determination circuit for determining the positive / negative of the chromaticity gain given to the gain selection circuits ODD6 and EVEN7, and 24 is the hue area identification circuit 2 and gain. This is a control signal generation circuit as a control circuit that outputs a control signal to each circuit in accordance with the output signal of the positive / negative determination circuit 25. The same thing as the components are denoted by the same reference numerals, and a description thereof will be omitted.
[0052]
The difference of the first embodiment from FIG. 1 is that the R-axis direction, G-axis direction, and B-axis direction gain conversion circuits ODD18, 19, and 20 perform color correction on the output signal of the gain control circuit ODD4. Among them, for an axis that is not orthogonal to the first hue axis ODD, gain conversion is performed to a ratio of red, green, and blue components that move the hue in a direction perpendicular to the axis. Similarly, the R axis direction, G axis direction, and B axis direction gain conversion circuits EVEN 21, 22, and 23 are orthogonal to the second hue axis EVEN of the two axes that perform color correction on the output signal of the gain control circuit EVEN5. For an axis that is not, the gain is converted to a ratio of red, green, and blue components that move the hue in a direction perpendicular to the axis. Further, a gain positive / negative discriminating circuit 25 for discriminating the positive / negative of the gain is added to the gain of chromaticity, and the control signal generating circuit 24 determines not only the output signal of the hue area discriminating circuit 2 but also the gain positive / negative judgment. The control signal is output to each circuit by the output signal of the circuit 25.
[0053]
While the first embodiment is a color correction apparatus that varies the saturation, the second embodiment is a color correction apparatus that varies the chromaticity.
[0054]
The operation of the color correction apparatus according to Embodiment 2 configured as described above will be described below with reference to FIG.
[0055]
FIG. 7 is an explanatory diagram for explaining how the hue region divided by the hue axes f1 to f6 described in the first embodiment is corrected in the second embodiment. Consider a case where each hue axis is moved in the direction indicated by the arrow in FIG. In FIG. 7, the gain constant is positive in the clockwise direction and negative in the counterclockwise direction. Further, the symbols such as −f5, −f6, and −f2 in FIG. 7 indicate the sign of the hue axis in the correction region. For example, in the region 1, the hue axis f5 is shown in FIG. Similarly, in region 2, the hue axis f6 is positive as shown in FIG. The R, G, B gain ratio is obtained by multiplying the original R, G, B gain ratio by the positive / negative of the hue axis, clockwise, and counterclockwise gain. Is shown.
[0056]
For example, for the hue region 1, as in the first embodiment, the hue axis selection circuit 3 outputs f5 as the first hue axis ODD and f4 as the second hue axis EVEN. Thereafter, the signal of the hue axis ODD is multiplied by a predetermined gain constant by the gain signal output from the gain selection circuit ODD6 by the gain control circuit ODD4, and the R-axis direction gain conversion circuit ODD18, G-axis direction gain conversion circuit ODD19, B It is output to the axial gain conversion circuit ODD20. Each gain conversion circuit ODD makes the input hue axis ODD signal perpendicular to the hue axis f1 (that is, the axis that is not orthogonal to the first hue axis ODD among the two axes sandwiching the hue region 1). The gain is converted to the ratio of R, G, and B in the direction and output to the corresponding adder circuits 15, 16 and 17.
[0057]
In this example, the original gain ratio of R, G, B in the direction perpendicular to the hue axis f1 (counterclockwise) is R: G: B = 1: 0: 0, and the hue used for correction is Since the sign in the region 1 of the axis f5 is negative as shown in FIG. 3 above, and the counterclockwise gain constant is negative, the final gain ratio of R, G, B is Since R: G: B = 1: 0: 0, in the R-axis direction gain conversion circuit ODD18, the G-axis direction gain conversion circuit ODD19, and the B-axis direction gain conversion circuit ODD20, R: G: B = 1: 0: The gain is converted to a ratio of 0 and output. If the gain-converted signal is added to the input three primary color signals, the phase of the hue axis f1, that is, the chromaticity, is varied using the signal of the hue axis f5.
[0058]
Similarly, the signal of the hue axis EVEN is multiplied by a gain signal output from the gain selection circuit EVEN7 by the gain control circuit EVEN5 and multiplied by a predetermined gain constant, and the R-axis direction gain conversion circuit EVEN21, G-axis direction gain conversion circuit EVEN22, B It is output to the axial gain conversion circuit EVEN23. Each gain conversion circuit EVEN makes a signal of the input hue axis EVEN perpendicular to the hue axis f2 (that is, an axis that is not orthogonal to the second hue axis EVEN among the two axes sandwiching the hue region 1). The gain is converted to the ratio of R, G, and B in the direction and output to the corresponding adder circuits 15, 16, and 17.
[0059]
In this example, the original ratio of R, G, B gain in the direction perpendicular to the hue axis f2 (clockwise direction) is R: G: B = −1: 0: 1, and is used for correction. Since the sign in the region 1 of the hue axis f4 is positive as shown in FIG. 3 and the clockwise gain constant is positive, the final gain ratio of R, G, B is Since R: G: B = −1: 0: 1, in the R-axis direction gain conversion circuit EVEN21, the G-axis direction gain conversion circuit EVEN22, and the B-axis direction gain conversion circuit EVEN23, R: G: B = −1: 0: The gain is converted to a ratio of 1 and output. If the gain-converted signal is added to the input three primary color signals, the phase of the hue axis f2, that is, the chromaticity, is varied using the signal of the hue axis f4.
[0060]
For example, when the hue axis f2 is moved in the counterclockwise direction perpendicular to the hue axis f2, the original ratio of R, G, B gain is R: G: B = 1: 0: -1. The sign in the region 2 of the hue axis f6 used for correction is positive as shown in FIG. 3 and the counterclockwise gain constant is negative, so that the final R, G, B The gain ratio is R: G: B = -1: 0: 1. In the R-axis direction gain conversion circuit EVEN21, the G-axis direction gain conversion circuit EVEN22, and the B-axis direction gain conversion circuit EVEN23, R: G: B The gain is converted to a ratio of −1: 0: 1 and added to the input three primary color signals.
[0061]
When the phase of the hue axis f4 at the boundary between the hue regions 3 and 4 is changed, the ratio of B and G to R of the correction signal is switched clockwise or counterclockwise. That is, for the hue region 3, clockwise rotation is R: G: B = -1: 0: -2, and counterclockwise rotation is R: G: B = 1: 2: 0.
[0062]
That is, in the hue region 3, when the hue axis f4 is moved clockwise using the hue axis f6, the original gain ratio of R, G, B is R: G: B = 1: 0: 2. Since the sign in the region 3 of the hue axis f6 used for correction is negative as shown in FIG. 3 and the clockwise gain constant is positive, the final R, G, The ratio of the gain of B is R: G: B = -1: 0: -2, whereas in the hue region 3, the hue axis f4 is moved counterclockwise using the hue axis f6. The ratio of the original R, G, B gain is R: G: B = 1: 2: 0, and the sign in the region 3 of the hue axis f6 used for correction is shown in FIG. And the counterclockwise gain constant is negative, so that the final R, G, B gain ratios are , R: G: B = 1: 2: 0 and becomes
Similarly, in the hue region 4, when the hue axis f4 is moved using the hue axis f2, clockwise rotation is R: G: B = -1: 0: -2 and counterclockwise rotation is R: G: B = 1: 2: 0.
[0063]
Therefore, when the hue axis f4 at the boundary between the hue regions 3 and 4 is moved, the gain ratio in the gain conversion circuits 21 to 23 is switched depending on whether the rotation is clockwise or counterclockwise, that is, whether the gain is positive or negative. For this reason, if the gain positive / negative determining circuit 25 determines that the gain is positive or negative, for example, the hue axis f4, the gain of the PG4 is determined, and the control signal generating circuit 24 determines the gain of the gain converting circuits 21 to 23. To switch.
[0064]
In addition to the hue axis f4 at the boundary between the hue regions 3 and 4, the gain switching is performed in addition to the hue axis f2 at the boundary between the hue regions 7 and 8, the hue axis f6 at the boundary between the hue regions 11 and 12, that is, the primary color signal. This is also necessary when moving the hue axis.
[0065]
As in the first embodiment, the correction amounts of the two axes that sandwich the correction region are zero on the other axes. (Because the hue axis of the correction signal and the hue axis of the region to be corrected intersect perpendicularly) Therefore, the phase change of each hue axis can be performed independently.
[0066]
In order to maintain the continuity of the phase change, the gain constants of the gain selection circuits ODD6 and EVEN7 are selected in the vicinity of the boundary of the hue region as in the first embodiment. For example, the gain constants of the correction signals f4 and f6 for the hue axis f2 are selected to be common. The same applies to the other hue regions.
[0067]
As described above, according to the second embodiment of the present invention, not only colors close to the six colors R, Ma, B, Cy, G, and Ye but also an intermediate color between these two colors can be effectively acted on. Correction of chromaticity to be performed can be performed independently.
[0068]
Also in the present embodiment, as in the first embodiment, the hue region is divided into 12 equal parts, so the ratio of the three primary color signals in the direction perpendicular to each hue axis is a simple ratio. Direction gain conversion circuit ODD18, G-axis direction gain conversion circuit ODD19, B-axis direction gain conversion circuit ODD20, R-axis direction gain conversion circuit EVEN21, G-axis direction gain conversion circuit EVEN22, and B-axis direction gain conversion circuit EVEN23 use multipliers. Even without it, it can be realized with a simple circuit by bit shifting digital data.
[0069]
Although not specifically described, the rewriting and setting of the values of the gain constants PG1 to PG12 can be appropriately realized by means such as a microcomputer (not shown). In the first embodiment and the second embodiment, the hue axis that divides the hue coordinates into 12 parts is selected. However, if there are hue axes that are orthogonal to the respective hue axes, for example, 24 divisions and 36 divisions are finer. It is needless to say that division may be used and the same effect can be obtained in a finer hue region.
[0070]
Needless to say, a color correction circuit that separately corrects the saturation and the chromaticity can be provided by combining the first and second embodiments.
[0071]
(Embodiment 3)
FIG. 8 is a block diagram showing the configuration of the color correction apparatus according to Embodiment 3 of the present invention.
[0072]
In FIG. 8, 26 is a reference color signal generation circuit for generating a reference signal for R, G, B three primary color signals, 27 is an input video signal for three primary color signals and a reference color signal generation circuit 26 for three primary color output signals. The switching circuit 28 for switching is a saturation / chromaticity correction circuit for correcting saturation or chromaticity similar to that in the first or second embodiment, and this saturation / chromaticity correction device 28 and the addition circuit 31. To 33 constitute a color correction apparatus that combines the above-described first or second embodiment.
[0073]
29 is a correction amount difference calculation for calculating a difference in color correction amount between a case where the signal input to the color correction device is a reference color signal and an input video signal obtained by actually capturing a color bar chart as a subject. A circuit 30 is a comparison circuit that compares a correction amount difference reference level, which is a preset reference level of the difference between correction amounts, with the output signal of the correction amount difference calculation circuit 29 and provides an output corresponding to the difference.
[0074]
The operation of the color correction apparatus according to the third embodiment configured as described above will be described below with reference to FIGS.
[0075]
FIG. 9 is a block diagram showing an example of the internal configuration of the correction amount difference calculation circuit 29 and the comparison circuit 30. In FIG. 9, 34 and 35 are delay flip-flops, 36 is an inverting gate, 37 and 38 are AND gates, 39 and 41 are subtractors, 40 is an absolute value circuit, and 42 is a gate circuit. FIG. 10 shows an example of a signal generated from the reference color signal generation circuit 26, and FIG. 11 is a signal waveform diagram of each part of the color correction apparatus of FIG.
[0076]
The reference signal generation circuit 26 generates, for example, a signal shown in FIG. This is a so-called color bar signal. As shown in FIG. 10, each of the three primary color signals RS, GS, and BS components is 100% (75%) level and 0 in units of time t obtained by dividing one horizontal scanning period into seven. Switch at% level. Therefore, a signal having a reference phase of R, G, B, Ma, Cy, Ye and a high saturation level is output. On the other hand, as the input video signal, a signal obtained by imaging a color bar chart having the same pattern as the reference signal is input.
[0077]
These signals are switched by the switching circuit 27 by the switching signal. For example, as shown in FIG. 11A, it is assumed that the switching signal is a signal that repeats High and Low at t / 2, and the reference signal is switched when Low, and the input signal is switched when High. Next, the output signal of the switching circuit 27 is input to the saturation and chromaticity correction circuit 28, and a saturation or chromaticity correction signal is output.
[0078]
Here, when only the saturation is corrected, for example, as shown in FIG. 11B, the correction signal output in the R signal period is output at the RSC level for the reference signal period and the RC level for the subject period. The Originally, the level of the reference signal period having a high saturation level is output largely. This signal is output to the correction amount difference calculation circuit 29 and the addition circuits 31 to 33 in the next stage.
[0079]
For example, the correction amount difference calculation circuit 29 is configured as shown in FIG. 9. When the correction amount signal shown in FIG. 11B is input, the inversion gate 36 and the AND gate 37 are input to the delay flip-flop 34. Thus, the clock input from the outside is enabled during the Low period of the switching signal, and is disabled at the moment when it changes from Low to High. Therefore, RSC data is held at that moment. On the other hand, in the delay flip-flop 35, the clock is enabled by the AND gate 38 during the period when the switching signal is High, and the RC data is output. Therefore, the subtracting circuit 39 outputs a signal RCD obtained by subtracting the correction amount RC of the subject period from the correction amount RSC of the reference signal period during the period in which the correction signal of the subject period is being output (the latter t / 2 period). Is done. The absolute value of this signal is taken by the next absolute value circuit 40 and is output as a correction amount difference signal as shown in FIG. In the comparison circuit 30, the subtraction circuit 41 subtracts a preset correction amount difference reference level RCDS from the correction amount difference signal, and the gate circuit 42 gates an unnecessary portion to perform the comparison shown in FIG. 11 (d). Output a signal. The correction amount difference comparison output is detected by a microcomputer or the like (not shown), and the saturation gain of the saturation and chromaticity correction circuit 28, that is, AG1 to AG12 in FIG. 1, is set so that this level becomes a constant value or zero. Control. This makes it possible to adjust the saturation correction so that the correction amount becomes a certain amount based on the reference signal.
[0080]
Further, the chromaticity can be similarly adjusted. It goes without saying that the same can be done for other hues.
[0081]
Needless to say, the correction amount difference may be output at a rate of, for example, a vertical scanning period (V) according to the convenience of processing by the microcomputer or the like.
[0082]
As described above, in the color correction apparatus according to the third embodiment, the saturation or chromaticity correction amount can be set to a correction amount set based on the reference signal. For example, a test chart can be displayed under the same conditions. If the image is taken, the color correction of the plurality of television cameras can be adjusted exactly the same.
[0083]
(Embodiment 4)
FIG. 12 is a block diagram showing the configuration of the color correction apparatus according to Embodiment 4 of the present invention.
[0084]
In FIG. 12, reference numeral 43 denotes a saturation or chromaticity correction circuit for correcting saturation or chromaticity equivalent to the circuit described in the first or second embodiment, the saturation and chromaticity correction circuit 43 and the addition circuit 44, 45 and 46 constitute the color correction apparatus of the first or second embodiment described above. Reference numeral 47 denotes a chroma detail circuit for correcting the frequency at high saturation, and reference numeral 48 denotes a gain control circuit for controlling the gain of the chroma detail circuit 47.
[0085]
The operation of the color correction apparatus according to the fourth embodiment configured as described above will be described below with reference to FIGS.
[0086]
FIG. 13 is a block diagram showing an example of the internal configuration of the chroma detail circuit 47. In FIG. 13, 49 is Y, a color difference matrix circuit, 50 to 52 are high-pass filters, 53 and 55 are adders, and 54 is a multiplier.
[0087]
The saturation and chromaticity correction circuit 43 outputs a saturation or chromaticity correction signal according to the saturation or chromaticity gain setting set by a microcomputer (not shown) or the like. This signal is added to the input three primary color signals by the adders 44 to 45, so that a signal with corrected saturation or chromaticity is created.
[0088]
In addition, as a color reproducibility correction, there is a chroma detail circuit that performs frequency correction at high saturation for the purpose of preventing the deterioration of high frequency at high saturation when the constant luminance principle is broken when NTSC composite signals are used. However, in a television camera or the like having the saturation and chromaticity correction circuit 43, the color tone is changed by correcting the saturation or chromaticity. Therefore, if faithful color reproducibility is to be pursued, chroma detail processing corresponding to the change in color tone is required, and the color-corrected signal is input to the chroma detail circuit 47 as shown in FIG. The circuit configuration is natural. In this case, a problem occurs depending on how to correct saturation or chromaticity.
[0089]
This will be described below. The internal configuration of the chroma detail circuit 47 is as shown in FIG. 13. When a color-corrected signal is input, the luminance signal Y and the color difference signals <R−Y>, <G -Y> and <BY> are output. <> Indicates a positive signal. These color difference signals are input to the high-pass filters 50 to 52, and the high-frequency components of those outputs are input to the adder 53 and added. Further, the gain is adjusted by the multiplier 54 by the gain control signal of the gain control circuit 48, and the luminance signal Y is added by the adder 55, and the luminance signal corrected in frequency is output.
[0090]
The above is the operation of the chroma detail circuit 47. Here, a case where saturation correction is performed as color correction will be considered. If the R monochromatic signal shown in FIG. 14 (a) is input (the solid line indicates no saturation correction and the dotted line indicates saturation correction), the luminance signal is as shown in FIG. 14 (b). Thus, since the color difference signal is only a positive signal, only <R−Y> is obtained, as shown in FIG. At this time, the output of the high-pass filter 50 is as shown in FIG. 5E when there is no saturation correction, and as shown in FIG. 5D when there is saturation correction. Further, when these signals are gain-controlled by the multiplier 54 and added to the luminance signal Y by the adder 55, the luminance signals corrected for chroma detail shown in (g) and (f) of FIG.
[0091]
As can be seen from each signal waveform diagram of FIG. 14, when the saturation correction is performed, when the correction is positive, that is, when the saturation is increased, the dotted line portion is added, so that the color difference signal level is increased and the chroma detail is also increased. . Therefore, when the correction amount is large, there is a problem that the chroma detail is too high and the sharpness is so high that the quality of the image quality is deteriorated. Therefore, in the color correction apparatus according to the fourth embodiment, the saturation or chromaticity gain and the chroma detail gain set by a microcomputer (not shown) or the like are input, and the chroma detail gain is determined based on the value of the saturation or chromaticity gain. And a gain control circuit 48 for supplying the adjusted chroma detail gain to the chroma detail circuit 47.
[0092]
In the case of this example, control is performed so that the gain is lowered so that the detail level of the dotted line in FIG. 14D becomes the detail level in FIG. As a result, it is possible to perform chroma detail correction with a gain setting that is almost the same as when saturation correction is not performed.
[0093]
Even in the case where saturation and chromaticity correction are performed, in the present embodiment, the chroma detail is corrected according to the color tone, but also at that time according to the gain settings of the saturation and chromaticity. By appropriately adjusting the chroma detail gain, the chroma detail level can be adjusted to an appropriate gain.
[0094]
As described above, in the color correction apparatus according to the fourth embodiment, it is possible to appropriately adjust the color tone and the chroma detail level in a television camera or the like provided with the saturation, the chromaticity correction circuit, and the chroma detail circuit. Color reproducibility and sharpness can be realized.
[0095]
In the above-described third and fourth embodiments, the present invention is applied to the color correction apparatus that corrects either the saturation or the chromaticity of the first or second embodiment. However, as another embodiment of the present invention, You may apply to the color correction apparatus which combines both form 1 and 2 and performs color correction of both saturation and chromaticity.
[0096]
In the third and fourth embodiments described above, the color correction apparatus according to the first and second embodiments is applied. However, as another embodiment of the present invention, the present invention is applied to a conventional color correction apparatus. Also good. For example, when applied to the conventional example of FIG. 15, the constant (gain) of the constant selection circuit 61 may be adjusted, or the gain of the chroma detail circuit may be controlled using this constant.
[0097]
【The invention's effect】
As described above, according to the present invention, it is possible to divide the hue coordinates into a plurality of parts with a simple configuration, and independently correct at least one of the saturation and chromaticity of each divided hue area, By finely dividing the hue region, at least one of the saturation and chromaticity of the intermediate color can be finely adjusted.
[0098]
In addition, by capturing the same test chart on multiple television cameras, it is possible to set exactly the same saturation and / or chromaticity correction, making it easy and accurate to adjust the color tone of each television camera. Can be adapted to
[0099]
In addition, it is possible to achieve both color correction of at least one of saturation and chromaticity and sharpness correction by chroma detail correction. In this way, a color correction apparatus that can achieve the above effects in color correction and color reproducibility can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a color correction apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a conceptual diagram when the hue coordinates are divided into 12 with 6 types of hue axes.
FIG. 3 is a hue area discrimination table showing the correspondence between each divided hue area and the positive / negative hue axis signal.
4 is an explanatory diagram illustrating an example of color correction in Embodiment 1. FIG.
FIG. 5 is an explanatory diagram for explaining how to select a gain and how to apply a gain;
FIG. 6 is a block diagram showing a configuration of a color correction apparatus according to a second embodiment of the present invention.
7 is an explanatory diagram for explaining chromaticity correction in Embodiment 2. FIG.
FIG. 8 is a block diagram showing a configuration of a color correction apparatus according to Embodiment 3 of the present invention.
9 is a block diagram showing an example of the internal configuration of a correction amount difference calculation circuit 29 and a comparison circuit 30. FIG.
10 is a diagram showing an example of a signal generated from a reference color signal generation circuit 26. FIG.
11 is a signal waveform diagram of a circuit of a color correction apparatus according to Embodiment 3. FIG.
FIG. 12 is a block diagram showing a configuration of a color correction apparatus according to Embodiment 4 of the present invention.
13 is a block diagram showing an example of an internal configuration of a chroma detail circuit 47. FIG.
FIG. 14 is a signal waveform diagram for explaining the operation of the chroma detail circuit 47;
FIG. 15 is a block diagram illustrating a configuration of a conventional color correction apparatus.
FIG. 16 is an explanatory diagram of a hue area in conventional color correction;
FIG. 17 is a conceptual diagram of a hue region in conventional color correction.
FIG. 18 is an explanatory diagram of the calculation principle of primary color components and complementary color components in conventional color correction;
FIG. 19 is a correction characteristic diagram according to the prior art.
[Explanation of symbols]
1 hue axis generation circuit
Two hue region identification circuit
3 hue axis selection circuit
4,5 gain control circuit ODD and gain control circuit EVEN
6, 7 gain select circuit ODD and gain select circuit EVEN
8,18R axial gain conversion circuit ODD
9, 19G axis direction gain conversion circuit ODD
10, 20B axial direction gain conversion circuit ODD
11, 21R axial direction gain conversion circuit EVEN
12, 22 G axis direction gain conversion circuit EVEN
13, 23B axial direction gain conversion circuit EVEN
14, 24 control signal generation circuit
15, 16, 17, 31, 32, 33, 44, 45, 46, 53, 55 adder
25 gain positive / negative judgment circuit
26 reference color signal generation circuit
27 switching circuit
28, 43 saturation and chromaticity correction circuit
29 correction amount difference calculation circuit
30 comparison circuit
34, 35 delay flip-flop
36 inversion gate
37, 38 AND gate
39, 41 subtractor
40 absolute value circuit
42 gate circuit
47 Chroma Detail Circuit
48 gain control circuit
49Y, color difference matrix circuit
50, 51, 52 high-pass filter
54 multiplier

Claims (7)

On the hue coordinates, a plurality of hue axes including axes of the three primary color signals of red, green, and blue and having an axis orthogonal to each axis are generated, and the color is divided for each hue region divided by these hue axes. A color correction device that performs correction,
A hue axis generation circuit that generates signals of the plurality of hue axes from an input video signal;
A hue area identification circuit for identifying the corresponding hue area from the signals of the plurality of hue axes;
A hue axis selection circuit that selects signals of the first and second hue axes that are respectively orthogonal to two hue axes sandwiching a hue region for performing color correction from the plurality of hue axis signals;
First and second gain varying means for varying the gain of the signals of the first and second hue axes, respectively;
For the output signal of the first gain varying means, the gain is set to the ratio of the red, green, and blue components of the two hue axes that sandwich the color correction area and that are not orthogonal to the first hue axis. First gain conversion means for converting
For the output signal of the second gain varying means, the gain is set to the ratio of the red, green, and blue components of the axes that are not orthogonal to the second hue axis among the two hue axes sandwiching the color correction region. Second gain conversion means for converting
An adder circuit for adding respective outputs in the R-axis direction, G-axis direction, and B-axis direction from the respective gain converting means to the corresponding three primary color signals of the input video signal;
Based on the identification signal from the hue area identification circuit, the hue axis selection circuit, the first and second gain variable means, and the first and second gain conversion means are controlled according to each hue area, and And a control circuit that independently corrects the saturation of the hue region. On the hue coordinates, a plurality of hue axes including axes of the three primary color signals of red, green, and blue and having an axis orthogonal to each axis are generated, and the color is divided for each hue region divided by these hue axes. A color correction device that performs correction,
A hue axis generation circuit that generates signals of the plurality of hue axes from an input video signal;
A hue area identification circuit for identifying the corresponding hue area from the signals of the plurality of hue axes;
A hue axis selection circuit that selects signals of the first and second hue axes that are respectively orthogonal to two hue axes sandwiching a hue region for performing color correction from the plurality of hue axis signals;
First and second gain varying means for varying the gain of the signals of the first and second hue axes, respectively;
For the output signal of the first gain varying means, a hue is set in a direction perpendicular to an axis that is not orthogonal to the first hue axis, out of two hue axes sandwiching a color correction region. First gain conversion means for converting the gain into a ratio of red, green and blue components to be moved;
For the output signal of the second gain varying means, the hue is set in the direction perpendicular to the axis that is not orthogonal to the second hue axis, out of the two hue axes sandwiching the color correction region. Second gain conversion means for converting the gain into a ratio of red, green and blue components to be moved;
An adder circuit for adding respective outputs in the R-axis direction, G-axis direction, and B-axis direction from the respective gain converting means to the corresponding three primary color signals of the input video signal;
A gain positive / negative determining circuit for determining the positive / negative of each gain of the first and second gain variable means;
Based on the identification signal from the hue region identification circuit and the determination signal of the gain positive / negative determination circuit, the hue axis selection circuit, the first and second gain variable means, and the first and second gain conversion means A color correction apparatus comprising: a control circuit that performs control according to a hue area and independently corrects the chromaticity of each hue area. 2. The correction gains before and after the hue axis are set to the same gain so that saturation discontinuity does not occur on the hue axis that divides each hue region in the first and second gain variable means. Color correction device. 3. The correction gains before and after the hue axis are set to the same gain setting in the first and second gain variable means so that discontinuity of chromaticity does not occur on the hue axis dividing each hue region. Color correction device. At least one of the color correction device according to claim 1 or 3 and the color correction device according to claim 2 or 4;
A reference color generation circuit for generating a reference color signal composed of three primary color signal components of red, green and blue;
A switching circuit that switches between an output signal of the reference color generation circuit and a video signal composed of three primary color signal components of red, green, and blue obtained from an actual imaging subject, and outputs the switching signal to the color correction device;
Based on the output signal of the gain conversion means of the color correction apparatus to which the output signal from the switching circuit is input, the color of the output signal of the reference color generation circuit and the case of the video signal of the actual imaging subject A correction amount difference calculation circuit for calculating a difference between at least one of the correction amount and the chromaticity,
A comparison circuit that compares the output signal of the correction amount difference calculation circuit with a signal of a predetermined reference level and provides an output according to the difference;
A color correction apparatus that controls a correction gain of the color correction apparatus based on an output of the comparison circuit. At least one of the color correction device according to claim 1 or 3 and the color correction device according to claim 2 or 4;
A chroma detail circuit that creates a color difference signal based on a color-corrected signal output from the color correction device, extracts a high-frequency component of the color difference signal, and performs frequency correction in a high-saturation image;
The gain of the chroma detail circuit is controlled based on a gain constant that determines the correction amount of at least one of saturation and chromaticity in the color correction device and a chroma detail gain constant that determines the correction amount of the chroma detail circuit. A color correction apparatus comprising a gain control circuit. The color correction apparatus according to claim 6, wherein the gain control circuit controls the gain of the chroma detail to be small when the gain constant of saturation is positive and large when the gain constant is negative.

Images