JP6698462B2 - Color correction device, display device, and color correction method - Google Patents

Description

  The present invention relates to a color correction device, a display device, and a color correction method.

  In a liquid crystal display device, additive color mixing is performed in which various primary colors such as red, green and blue are mixed to form various colors. Therefore, in the liquid crystal display device, the gradation values respectively indicating the three primary color amounts are input, and the color corresponding to the input three gradation values is displayed.

  However, if the displayed color does not change smoothly when all or part of the input three gradation values gradually changes, the observer who observes the displayed color gives an unnatural impression. receive. This problem becomes particularly noticeable for white gradation.

  Therefore, in order to make the displayed color change smoothly when all or a part of the three gradation values gradually change, the gradation value and the display indicating the primary color amount of the input primary color are displayed. The γ characteristic showing the relationship with the brightness of the primary color component of the color to be corrected is corrected.

  In many cases, the γ characteristic is corrected according to a look-up table. The look-up table defines a gradation conversion characteristic and includes a plurality of input gradation values serving as an index and an output gradation value corresponding to each of the plurality of input gradation values. When the γ characteristic is corrected according to the look-up table, gradation conversion is performed on the gradation value before gradation conversion according to the look-up table. In the gradation conversion, the output gradation value corresponding to the input gradation value that matches the gradation value before the gradation conversion is specified, and the specified output gradation value is set as the gradation value after the gradation conversion. It

  When one look-up table common to all the three primary colors is prepared and the γ characteristic is corrected according to the one look-up table prepared, three look-up tables are prepared. The gradation conversion is performed on each of the gradation values before the gradation conversion. In this case, the ratio of the three gradation values after the gradation conversion cannot be made different from the ratio of the three gradation values before the gradation conversion, so that the color cannot be corrected.

  In order to be able to perform color correction, it is proposed to prepare three look-up tables respectively corresponding to the three primary colors and to correct the γ characteristic according to the prepared three look-up tables. Has been done. In this case, the ratio of the three gradation values after the gradation conversion can be made different from the ratio of the three gradation values before the gradation conversion, so that the color can be corrected for white. However, depending on the characteristics of the liquid crystal display device, it may not be possible to appropriately perform color correction for an arbitrary color.

  It has been proposed to perform color correction according to a three-dimensional lookup table so that color correction can be appropriately performed for any color regardless of the characteristics of the liquid crystal display device. The three-dimensional look-up table includes a plurality of sets of input grayscale values serving as an index, and a set of output grayscale values for each of the plurality of sets of input grayscale values. When the color correction is performed according to the three-dimensional look-up table, gradation conversion is performed on the three gradation values according to the three-dimensional look-up table. In gradation conversion, a set of output gradation values corresponding to a set of input gradation values that matches a set of gradation values before gradation conversion is specified, and the specified set of output gradation values is gradation. The converted gradation values are set. The technology described in each of Patent Documents 1 and 2 is an example thereof.

International Publication No. 2009/101802 JP, 2002-016939, A

  In a liquid crystal display device, a frame image must be displayed immediately after a signal expressing the frame image is input. Therefore, the signal processing including color correction must be performed in real time. Therefore, when the color correction is performed according to the three-dimensional look-up table, the three-dimensional look-up table is preferably incorporated in hardware.

However, in the conventional color correction performed according to the three-dimensional look-up table, when each of the three gradation values is represented by an 8-bit bit string, all combinations of the three gradation values are combined. In order to cover the above, correction data of 256 ³ ×3=50,331,648 bits must be held in a three-dimensional lookup table, and many resources are required to incorporate the three-dimensional lookup table in hardware. You will need it. Therefore, it is impractical to incorporate the three-dimensional lookup table in hardware.

  It is also possible to reduce the required resources by widening the grid point spacing in the three-dimensional lookup table and reducing the correction data. However, when the grid point interval is widened and the correction data is reduced, the γ characteristic and the color may not be properly corrected between the grid points.

  These problems also occur when color correction is performed in a device other than the liquid crystal display device.

  The present invention is made to solve these problems. The problem to be solved by the present invention is to appropriately correct the γ characteristic for each of the three primary colors and white, appropriately correct the color for white, and correct the color for an arbitrary color with a small amount of resources. Do it properly.

  The present invention relates to a color correction device and a color correction method. The color correction device may be incorporated in the display device.

  The first one-dimensional look-up table, the second one-dimensional look-up table, and the third one-dimensional look-up table define gradation conversion characteristics for the first primary color, the second primary color, and the third primary color, respectively. To do.

  According to the first one-dimensional look-up table, the second one-dimensional look-up table, and the third one-dimensional look-up table, the first primary gradation value, the second primary gradation value, and the third primary gradation value, respectively. The gradation conversion is performed on the primary gradation value of. A first secondary gradation value, a second secondary gradation value and a third secondary gradation value are obtained.

  The first primary gradation value, the second primary gradation value, and the third primary gradation value represent the primary color amounts of the first primary color, the second primary color, and the third primary color, respectively. The first secondary tone value, the second secondary tone value, and the third secondary tone value indicate the primary color amounts of the first primary color, the second primary color, and the third primary color, respectively.

  The fourth one-dimensional look-up table, the fifth one-dimensional look-up table, and the sixth one-dimensional look-up table define gradation conversion characteristics regarding white.

  According to the fourth one-dimensional look-up table, the fifth one-dimensional look-up table, and the sixth one-dimensional look-up table, the first primary gradation value, the second primary gradation value, and the third primary gradation value, respectively. The gradation conversion is performed on the primary gradation value of. The fourth secondary gradation value, the fifth secondary gradation value and the sixth secondary gradation value are obtained.

  The fourth secondary gradation value, the fifth secondary gradation value, and the sixth secondary gradation value represent the primary color amounts of the first primary color, the second primary color, and the third primary color, respectively.

  From the first primary gradation value, the second primary gradation value, and the third primary gradation value, the first secondary gradation value and the fourth secondary gradation value Of the contribution to the third gradation value is determined to be the first contribution magnitude, and the second third gradation value of each of the second second gradation value and the fifth second gradation value is determined. The magnitude of the contribution to the tonal value is determined to be the magnitude of the second contribution, and the contribution of each of the third secondary tone value and the sixth secondary tone value to the third tertiary tone value is determined. The contribution magnitude is determined to be the third contribution magnitude.

  The first tertiary gradation value, the second tertiary gradation value, and the third gradation value indicate the primary color amounts of the first primary color, the second primary color, and the third primary color, respectively.

  The first 2nd gradation value and the 4th 2nd gradation value are adjusted so that the contribution of each of them to the 1st 3rd gradation value becomes the 1st contribution magnitude. A first tertiary gradation value is derived from the next gradation value and the fourth secondary gradation value, and a second third gradation value of each of the second secondary gradation value and the fifth secondary gradation value is obtained. The second tertiary gradation value is derived from the second secondary gradation value and the fifth secondary gradation value so that the contribution to the next gradation value becomes the second contribution. The third contribution level of each of the third secondary gray level value and the sixth secondary gray level value to the third tertiary gray level value is set to the third contribution level. A third tertiary gradation value is derived from the secondary gradation value and the sixth secondary gradation value.

  According to the present invention, correction is performed for each of the three primary colors according to the one-dimensional lookup table, and white is corrected according to the one-dimensional lookup table. Further, the applied amount of the former and latter corrections is changed according to the color represented by the set of gradation values before correction. Therefore, the γ characteristic is appropriately corrected for each of the three primary colors and white, and the color is appropriately corrected for white. In addition, color correction is appropriately performed for any color.

  Further, according to the present invention, since the γ characteristic and the color are corrected according to the one-dimensional lookup table, the γ characteristic and the color are corrected with a small amount of resources.

3 is a block diagram showing the liquid crystal display device of Embodiment 1. FIG. FIG. 6 is a diagram showing an example of gradation conversion in the first embodiment. 3 is a block diagram showing the color correction apparatus of the first embodiment. FIG. 7 is a block diagram showing a color correction device according to a second embodiment. FIG. FIG. 9 is a block diagram showing a color correction device according to a third embodiment.

Embodiment 1
1.1 Liquid Crystal Display Device FIG. 1 is a block diagram showing the liquid crystal display device according to the first embodiment.

  The liquid crystal display device 1000 shown in FIG. 1 includes an input connector 1022, a timing controller 1024, a gate driver integrated circuit (IC) 1026, a source driver IC 1028, and a liquid crystal panel 1030. The timing controller 1024 includes a signal processing unit 1042. The signal processing unit 1042 includes a color correction unit 1062. The liquid crystal panel 1030 includes a plurality of pixels 1082. The liquid crystal display device 1000 may include components other than these components.

  The input signal 1102 includes a signal including image data. The image data includes gradation values Rin, Gin, and Bin for each of the plurality of pixels 1082.

  The input signal 1102 is a digital electric signal, is transmitted by wire, is input to the input connector 1022, and is input to the timing controller 1024 via the input connector 1022. The input signal 1102 may be replaced with a wirelessly transmitted input signal, and the input connector 1022 may be replaced with a receiver that receives the wirelessly transmitted input signal. The input signal 1102 may be replaced with an input signal which is an analog electric signal, and the liquid crystal display device 1000 converts the input signal which is an analog electric signal into a digital electric signal to obtain gradation values Rin, Gin and Bin A A /D converter may be provided.

  The signal processing unit 1042 outputs a signal 1122 used to control the timing of driving each of the plurality of pixels 1082. The output signal 1122 is input to the gate driver IC 1026. In addition, the signal processing unit 1042 processes a signal including the input image data and outputs a signal 1124 used for controlling a color displayed in each of the plurality of pixels 1082. The output signal 1124 is input to the source driver IC 1028.

  The color correction unit 1062 corrects the color when the signal 1124 is generated. When color correction is performed, the gradation values Rin, Gin, and Bin before correction are input to the color correction unit 1062 for each of the plurality of pixels 1082, and the gradation values Rout, Gout, and Bout after correction are the colors. It is output from the correction unit 1062.

  The gate driver IC 1026 outputs an ON/OFF signal 1142 for controlling ON/OFF of a thin film transistor (TFT) provided in each of the plurality of pixels 1082 to the TFT gate based on the signal 1122.

  The source driver IC 1028 outputs a color signal 1144 for controlling the color displayed in each of the plurality of pixels 1082 to the TFT source based on the signal 1124. The color signal 1144 reflects the corrected gradation values Rout, Gout, and Bout that form the RGB data.

  The gate driver IC 1026 and the source driver IC 1028 configure a drive circuit that causes each pixel of the plurality of pixels 1082 to display a color represented by a set of corrected gradation values Rout, Gout, and Bout on the pixel. The drive circuit may be replaced with a drive circuit having a structure different from that of the drive circuit.

  The liquid crystal panel 1030 is a display panel. An image is displayed on the liquid crystal panel 1030 by displaying the color represented by the set of the corrected gradation values Rout, Gout, and Bout for each of the plurality of pixels 1082 on the pixel.

1.2 Gradation Conversion FIG. 2 is a diagram showing an example of gradation conversion in the first embodiment.

The one-dimensional lookup table 1202 shown in FIG. 2 defines gradation conversion characteristics when gradation conversion from gradation values before gradation conversion to gradation conversion after gradation conversion is performed. ..., 159, 160, 161,..., 256, 256 input grayscale values 1222, corresponding to 256 input grayscale values 1,..., 164, 169, 172, respectively. .., 256 output gradation values 1224. Each of the input gradation values 1222 is represented by an 8-bit bit string. Each of the output gradation values 1224 is represented by an 8-bit bit string. The 256 input gradation values 1222 may be replaced with a plurality of input gradation values each represented by a bit string of 7 bits or less or 9 bits or more. The 256 output grayscale values 1224 may be replaced with a plurality of output grayscale values each represented by a bit string of 7 bits or less or 9 bits or more.

  When gradation conversion is performed according to the one-dimensional lookup table 1202, the input gradation value that matches the gradation value before gradation conversion is selected from the 256 input gradation values 1222, and the selected input floor The output gradation value corresponding to the gradation value is set as the gradation value after gradation conversion. As a result, the gradation value before gradation conversion is converted into the gradation value after gradation conversion. For example, when the gradation value before gradation conversion is 159, 160 or 161, the gradation value after gradation conversion becomes 164, 169 or 172, respectively.

1.3 Color Correction Device FIG. 3 is a block diagram showing the color correction device according to the first embodiment.

  The color correction device 1290 shown in FIG. 3 is incorporated in the liquid crystal display device 1000 to become a color correction unit 1062, which is a primary color correction unit 1302, a white correction unit 1304, a coefficient calculation unit 1306, and a gradation value calculation unit 1308. Equipped with. The primary color correction unit 1302 includes a primary color gradation conversion unit 1322. The white correction unit 1304 includes a white gradation conversion unit 1342. The color correction device 1290 may include components other than these components.

  The color correction device 1290 may be incorporated in a liquid crystal display device having a configuration different from that of the liquid crystal display device 1000, a display device other than the liquid crystal display device, a device other than the display device, and the like.

  The input signal 1102 includes primary gradation values Rin, Gin and Bin indicating the primary color amounts of the three primary colors red (R), green (G) and blue (B), respectively. The primary gradation values Rin, Gin, and Bin are gradation values before correction, and are input to each of the primary color correction unit 1302, the white correction unit 1304, and the coefficient calculation unit 1306. R, G and B may be replaced with three primary colors other than R, G and B.

  The primary color gradation conversion unit 1322 defines gradation conversion characteristics for R, G, and B, which are a set of one-dimensional lookup tables for correcting the primary gradation values Rin, Gin, and Bin. It holds one-dimensional lookup tables R_LUT, G_LUT and B_LUT for primary colors. The primary color one-dimensional lookup tables R_LUT, G_LUT, and B_LUT are for correcting the γ characteristics of R, G, and B, respectively, and are preferably implemented by hardware.

  The primary color gradation conversion unit 1322 performs gradation conversion on the primary gradation value Rin according to the one-dimensional lookup table R_LUT to obtain the gradation-converted gradation value R′r. The gradation value G'g after gradation conversion is obtained by performing gradation conversion on the primary gradation value Gin according to the lookup table G_LUT, and the primary gradation value Bin according to the one-dimensional lookup table B_LUT. The gradation value is converted to obtain the gradation value B′b after the gradation conversion. The tone values R′r, G′g and B′b after tone conversion output from the tone conversion unit 1322 for the primary color are the secondary tone values R directly output from the correction unit 1302 for the primary color. Become'r, G'g and B'b. As a result, the primary color correction unit 1302 obtains the secondary gradation values R'r, G'g and B'b. The secondary gradation values R'r, G'g and B'b indicate the primary color amounts of R, G and B, respectively.

  The white gradation conversion unit 1342 is a set of one-dimensional lookup tables for correcting the primary gradation values Rin, Gin, and Bin, and is a one-dimensional defining gradation conversion characteristic for white (W). It holds lookup tables W_LUT(R), W_LUT(G) and W_LUT(B). Since W is a mixed color of R, G, and B, the gradation conversion characteristics for W are one-dimensional lookup tables W_LUT(R), W_LUT(G), and W_LUT that define the gradation conversion characteristics for R, G, and B, respectively. It is defined by the set of (B). The one-dimensional lookup tables W_LUT(R), W_LUT(G) and W_LUT(B) are for correcting the γ characteristic and color of W, and are preferably implemented by hardware.

  The gradation conversion unit 1342 for white performs gradation conversion on the primary gradation value Rin according to the one-dimensional lookup table W_LUT(R) to obtain the gradation value R′w after gradation conversion. The gradation value G'w after gradation conversion is obtained by performing gradation conversion on the primary gradation value Gin according to the one-dimensional lookup table W_LUT(G). ), the gradation conversion is performed on the primary gradation value Bin to obtain the gradation value B′w after the gradation conversion. The grayscale values R′w, G′w and B′w after the grayscale conversion output from the white grayscale conversion unit 1342 are the secondary grayscale values R directly output from the white correction unit 1304. Become'w, G'w and B'w. As a result, the white correction unit 1304 obtains the secondary gradation values R'w, G'w, and B'w. The secondary gradation values R'w, G'w and B'w indicate the primary color amounts of R, G and B, respectively.

  The coefficient calculation unit 1306 calculates weighting coefficients K_R, K_G, K_B, K_W(R), K_W(G) and K_W(B) from the primary gradation values Rin, Gin and Bin. The weighting factors K_R, K_G, K_B, K_W(R), K_W(G) and K_W(B) are respectively one-dimensional lookup tables R_LUT, G_LUT, B_LUT, W_LUT(R), W_LUT(G) and W_LUT(B). Corresponding to. Each of the weighting factors K_R, K_G, K_B, K_W(R), K_W(G) and K_W(B) is a gradation after gradation conversion obtained by gradation conversion performed according to the corresponding one-dimensional lookup table. Indicates the value weight. Therefore, the weighting factors K_R, K_G, K_B, K_W(R), K_W(G) and K_W(B) are respectively the secondary gradation values R'r, G'g, B'b, R'w, G'. The weights of w and B'w are shown.

  The tone value calculation unit 1308 calculates the weighted sum K_R*R'r+K_W(R)*R'w by multiplying the secondary tone values R'r and R'w by the weighting factors K_R and K_W(R), respectively. To the third-order gradation value Rout, and the weighting factors K_G and K_W(G) are respectively multiplied to the second-order gradation values G'g and G'w to obtain a weighted sum K_G*G'g+K_W(G)*G'. Weighting sum K_B*B'b+K_W(B)*B in which w is set to the third-order gradation value Gout and the weighting factors K_B and K_W(B) are respectively multiplied to the second-order gradation values B'b and B'w. 'Set w to the third gradation value Bout. The third-order gradation values Rout, Gout, and Bout included in the output signal 1362 are gradation values after correction, and indicate the primary color amounts of R, G, and B, respectively.

  The smaller the weighting coefficient K_R, the smaller the contribution of the secondary gradation value R'r to the tertiary gradation value Rout, and the larger the weighting coefficient K_R, the tertiary gradation value Rout of the secondary gradation value R'r. As the weighting coefficient K_W(R) decreases, the contribution of the secondary gradation value R'w to the tertiary gradation value Rout decreases, and as the weighting coefficient K_W(R) increases, the secondary gradation The contribution of the value R'w to the third gradation value Rout becomes large. Therefore, the weighting factors K_R and K_W(R) represent the magnitudes of the contributions of the secondary gradation values R′r and R′w to the tertiary gradation value Rout, respectively.

  Similarly, the weighting factors K_G and K_W(G) represent the magnitudes of the contributions of the secondary gradation values G'g and G'w to the tertiary gradation value Gout, respectively, and the weighting factors K_B and K_W(B ) Expresses the magnitude of the contribution of the secondary gradation values B'b and B'w to the tertiary gradation value Bout, respectively.

  Therefore, the coefficient calculation unit 1306 determines that the magnitude of the contribution of each of the secondary gradation values R'r and R'w to the tertiary gradation value Rout is represented by the weighting coefficients K_R and K_W(R). The magnitude of the contribution of each of the secondary gradation values G'g and G'w to the tertiary gradation value Gout is determined to be represented by the weighting factors K_G and K_W(G). A determining unit that determines the magnitude of the contribution of each of the grayscale values B'b and B'w to the third-order grayscale value Bout to that represented by the weighting factors K_B and K_W(B) is formed.

  Further, in the gradation value calculation unit 1308, the degree of contribution of each of the secondary gradation values R'r and R'w to the tertiary gradation value Rout is represented by the weighting factors K_R and K_W(R). So as to obtain the 3rd gradation value Rout from the 2nd gradation values R'r and R'w, and to each 3rd gradation value Gout of the 2nd gradation values G'g and G'w The 3rd gradation value Gout is derived from the 2nd gradation values G'g and G'w so that the magnitude of the contribution of is expressed by the weighting factors K_G and K_W(G). The secondary tone values B'b and B'b and B'w are adjusted so that the magnitude of the contribution of each of the values B'b and B'w to the third tone value Bout is represented by the weighting factors K_B and K_W(B). A derivation unit that derives the third gradation value Bout from B′w is configured.

  When the weighting factors K_R, K_G, K_B, K_W(R), K_W(G) and K_W(B) are calculated, the W of the color represented by the combination of the primary gradation values Rin, Gin and Bin The index Kw indicating the closeness is calculated by the equation (1).

  Kw=1-(RGBin_MAX-RGBin_MIN)/RGBin_MAX (1)

  The maximum value RGBin_MAX is the maximum value of the primary gradation values Rin, Gin and Bin, and is calculated by the equation (2).

  RGBin_MAX=MAX(Rin,Gin,Bin) (2)

  The minimum value RGBin_MIN is the minimum value of the primary gradation values Rin, Gin and Bin, and is calculated by equation (3).

  RGBin_MIN=MIN(Rin,Gin,Bin) (3)

  When the color represented by the combination of the primary gradation values Rin, Gin, and Bin is W, Rin=Gin=Bin, so that the index Kw is 1, and the color is R, G, or B. In some cases, two of the first-order gradation values Rin, Gin, and Bin become 0, and thus become 0, and the closer the color is to white, the larger. Therefore, the index Kw becomes a factor indicating the weight of W, and the index 1-Kw obtained by subtracting the index Kw from 1 becomes a factor indicating the sum of the weights of R, G and B.

  Further, the index Kr indicating the closeness of the color represented by the primary gradation values Rin, Gin and Bin to R is calculated by the formula (4), and the index Kg indicating the closeness of the color to G is calculated by the formula (4). The index Kb calculated from (5) and indicating the proximity of the color to B is calculated from equation (6).

Kr=(1-Kw)*Rin/(Rin+Gin+Bin) (4)
Kg=(1-Kw)*Gin/(Rin+Gin+Bin) (5)
Kb=(1-Kw)*Bin/(Rin+Gin+Bin) (6)

  The index 1-Kw is a factor indicating the sum of R weight, G weight, and B weight, and Rin/(Rin+Gin+Bin), Gin/(Rin+Gin+Bin) and Bin/(Rin+ The ratio of (Gin+Bin) indicates the ratio of the R weight, the G weight, and the B weight. Therefore, according to the equations (4), (5) and (6), the sum of the R weight, the G weight and the B weight is proportionally distributed to each of the R, G and B primary colors according to the weight of each primary color. It

  Furthermore, the weighting factors K_W(R), K_W(G), K_W(B), K_R, K_G and K_B are expressed by equations (7), (8), (9), (10), (11) and (12), respectively. ).

K_W(R)=Kw/(Kr+Kw) (7)
K_W(G)=Kw/(Kg+Kw) (8)
K_W(B)=Kw/(Kb+Kw) (9)
K_R=1-K_W(R) (10)
K_G=1-K_W(G) (11)
K_B=1-K_W(B) (12)

  The index Kr is a factor indicating the weight of R, and the index Kw is a factor indicating the weight of W. Therefore, the weighting coefficient K_W(R), which is the ratio of the index Kw to the sum of the indices Kr and Kw, specifies the ratio to which the correction for W most affected by the characteristics of the liquid crystal display device 1000 should be applied. Similarly, each of the weighting factors K_W(G) and K_W(B) also specifies the ratio to which the correction for W most affected by the characteristics of the liquid crystal display device 1000 should be applied.

  Equations (1) to (12) are examples, and weighting factors K_W(R), K_W(G), K_W(B), K_R, K_G and K_B are different from equations (1) to (12). It may be calculated by a formula.

  Each of the weighting factors K_W(R), K_W(G), K_W(B), K_R, K_G and K_B has a value of 0 or more and 1 or less. Further, the sum of the weight coefficient K_R and the weight coefficient K_W(R) becomes 1, the sum of the weight coefficient K_G and the weight coefficient K_W(G) becomes 1, and the sum of the weight coefficient K_B and the weight coefficient K_W(B) becomes The sum is 1. As a result, the third gradation values Rout, Gout and Bout are obtained by a simple weighted sum.

  According to the weighting factors K_W(R), K_W(G), K_W(B), K_R, K_G and K_B, the color represented by the combination of the primary gradation values Rin, Gin and Bin is close to white and the index Kw Is larger, the contribution of the secondary gradation value R'r to the tertiary gradation value Rout is smaller, the contribution of the secondary gradation value R'w to the tertiary gradation value Rout is larger, and the secondary The contribution of the gradation value G'g to the tertiary gradation value Gout is small, the contribution of the secondary gradation value G'w to the tertiary gradation value Gout is large, and the secondary gradation value B'b Of the secondary gradation value B'w to the tertiary gradation value Bout is large, and the contribution of the secondary gradation value B′w to the tertiary gradation value Bout is large.

  A coefficient indicating the magnitude of contribution of each of the secondary gradation values R'r and R'w to the tertiary gradation value Rout, and each tertiary gradation of each of the secondary gradation values G'g and G'w. The coefficient indicating the degree of contribution to the value Gout and the coefficient indicating the degree of contribution of each of the secondary gradation values B'b and B'w to the tertiary gradation value Bout are the tertiary gradation value. When the calculation formula for deriving Rout, Gout, and Bout is replaced with another calculation formula, it is replaced with a coefficient according to the other calculation formula.

  According to the first embodiment, the γ characteristics are corrected for R, G, and B according to the one-dimensional lookup tables R_LUT, G_LUT, and B_LUT, and the one-dimensional lookup tables W_LUT(R), W_LUT(G). And W_LUT(B), the γ characteristic and color of W are corrected. Further, the gradation values R'r, G'g and B'obtained by the former correction and the gradation values R'w, G'w and B'w obtained by the latter correction after the correction are respectively corrected. The magnitude of the contribution to the values Rout, Gout, and Bout is changed according to the color represented by the set of tone values Rin, Gin, and Bin before correction. Therefore, the γ characteristic is appropriately corrected for each of R, G, B, and W, and the color is appropriately corrected for W. In addition, color correction is appropriately performed for any color. Therefore, in the liquid crystal display device 1000 in which the color correction device 1290 is incorporated, color correction is performed for any color according to the characteristics of the liquid crystal panel 1030.

  Further, according to the first embodiment, the γ characteristic and the color are corrected according to the one-dimensional lookup tables R_LUT, G_LUT, B_LUT, W_LUT(R), W_LUT(G) and W_LUT(B). The γ characteristic and the color are corrected by.

Second Embodiment
The second embodiment relates to a color correction device that replaces the color correction device of the first embodiment.

  In the color correction apparatus according to the first embodiment, each primary color is corrected according to one one-dimensional lookup table, but in the color correction apparatus according to the second embodiment, each primary color has three one-dimensional lookup tables. Corrected according to the table. The purpose is to improve the accuracy of color correction for each primary color.

  FIG. 4 is a block diagram showing the color correction apparatus of the second embodiment.

  The color correction apparatus 2000 shown in FIG. 4 includes a primary color correction unit 2022, a white correction unit 2024, a coefficient calculation unit 2026, and a gradation value calculation unit 2028. The primary color correction unit 2022 includes a primary color gradation conversion unit 2042 and a calculation unit 2044. The white correction unit 2024 includes a white gradation conversion unit 2062. The white correction unit 2024, the coefficient calculation unit 2026, the gradation value calculation unit 2028, and the white gradation conversion unit 2062, which are included in the color correction apparatus 2000 of the second embodiment, are respectively the color correction apparatus of the first embodiment. This is the same as the white correction unit 1304, coefficient calculation unit 1306, tone value calculation unit 1308, and white tone conversion unit 1342 provided in 1290. Therefore, in the following, the primary color correction unit 2022, the primary color gradation conversion unit 2042, and the calculation unit 2044 will be described exclusively.

  The primary color gradation conversion unit 2042 has one-dimensional lookup tables R_LUT(R), R_LUT(G) and R_LUT(B), each of which defines gradation conversion characteristics regarding R, and each gradation conversion characteristic regarding G. One-dimensional look-up tables G_LUT(R), G_LUT(G) and G_LUT(B) to be defined, and one-dimensional look-up tables B_LUT(R), B_LUT(G) and B_LUT each of which define gradation conversion characteristics regarding B. Hold (B). The one-dimensional lookup tables R_LUT(R), R_LUT(G) and R_LUT(B) for the primary colors are for correcting the outputs of R, G and B with respect to the primary gradation value Rin, and are preferably Implemented in hardware. The one-dimensional lookup tables G_LUT(R), G_LUT(G) and G_LUT(B) for the primary colors are for correcting the outputs of R, G and B for the primary gradation value Gin, and are preferably Implemented in hardware. The one-dimensional lookup tables B_LUT(R), B_LUT(G) and B_LUT(B) for the primary colors are for correcting the outputs of R, G and B with respect to the primary gradation value Bin, and are preferably Implemented in hardware.

  The primary color gradation conversion unit 2042 performs gradation conversion on the primary gradation value Rin in accordance with the one-dimensional lookup tables R_LUT(R), R_LUT(G) and R_LUT(B) to respectively generate gradations. Obtain the converted gradation values R'r(R), R'r(G) and R'r(B) according to the one-dimensional lookup table G_LUT(R), G_LUT(G) and G_LUT(B). By performing gradation conversion on the primary gradation value Gin, gradation values G'g(R), G'g(G) and G'g(B) after gradation conversion are obtained, respectively, one-dimensionally. By performing gradation conversion on the primary gradation value Bin according to the lookup tables B_LUT(R), B_LUT(G) and B_LUT(B), the gradation values B'b(R) after gradation conversion respectively. ,B'b(G) and B'b(B) are obtained. Each of the gradation values R'r(R), G'g(R), and B'b(R) after gradation conversion represents the amount of R primary color. Each of the gradation values R′r(G), G′g(G), and B′b(G) after gradation conversion indicates the amount of G primary color. Each of the gradation values R′r(B), G′g(B), and B′b(B) after gradation conversion indicates the amount of B primary color.

  The calculation unit 2044 adds the gradation values R′r(R), G′g(R) and B′b(R) after gradation conversion to obtain a secondary gradation value R′r=R′r. (R)+G'g(R)+B'b(R) is obtained and the gradation values after gradation conversion R'r(G), G'g(G) and B'b(G) are added. By combining them, the secondary gradation value G'g=R'r(G)+G'g(G)+B'b(G) is obtained, and the gradation value after gradation conversion R'r(B), By adding G'g(B) and B'b(B) together, the secondary gradation value B'b=R'r(B)+G'g(B)+B'b(B) is obtained. The gradation values R′r, G′g, and B′b after the gradation conversion are output from the primary color correction unit 2022.

  According to the second embodiment, similarly to the first embodiment, the γ characteristic is appropriately corrected for each of R, G, B and W, the color is appropriately corrected for W, and an arbitrary color is obtained. The color correction is properly performed for. When the color correction device 2000 is incorporated in the liquid crystal display device 1000 in place of the color correction device 1290, color correction according to the characteristics of the liquid crystal panel 1030 is performed for any color.

  Further, according to the second embodiment, similarly to the first embodiment, the γ characteristic and the color are corrected with few resources.

  In addition, according to the second embodiment, the accuracy of color correction for each primary color is improved.

Third Embodiment
The third embodiment relates to a color correction device that replaces the color correction device of the first embodiment.

In the color correction apparatus according to the first embodiment, the weighting factors K_R, K_G, K_B, K_W( corresponding to the one-dimensional lookup tables R_LUT, G_LUT, B_LUT, W_LUT(R), W_LUT(G) and W_LUT(B), respectively. R), K_W(G) and K_W(B) are calculated and correction is performed according to the six one-dimensional lookup tables. In the color correction apparatus according to the third embodiment, the one-dimensional lookup table R_LUT , One common weighting coefficient K_RGB corresponding to G_LUT and B_LUT is calculated, and one common weighting coefficient K_W corresponding to one-dimensional lookup table W_LUT(R) , W_LUT(G) and W_LUT(B) is calculated, 6 The correction is performed according to the one-dimensional lookup table. The purpose is to reduce the amount of calculation required to calculate the weighting coefficient.

  FIG. 5 is a block diagram showing the color correction apparatus of the third embodiment.

The color correction apparatus 3000 shown in FIG. 5 is incorporated in the liquid crystal display device 1000 to become a color correction section 1062, which includes a primary color correction section 3022, a white correction section 3024, a coefficient calculation section 3026, and a gradation value calculation section 3028. Equipped with. The primary color correction unit 3022 includes a primary color gradation conversion unit 3042. The white correction unit 3024 includes a white gradation conversion unit 3062. The color correction device 3000 may include components other than these components. The primary color correction unit 3022, the white correction unit 3024, the primary color gradation conversion unit 3042, and the white gradation conversion unit 3062 provided in the color correction apparatus 3000 of the third embodiment are the same as those of the first embodiment. This is the same as the primary color correction unit 1302, the white correction unit 1304, the primary color gradation conversion unit 1322, and the white gradation conversion unit 1342 provided in the color correction device 1290 of FIG. Therefore, hereinafter, the coefficient calculation unit 3026 and the gradation value calculation unit 3028 will be described exclusively.

  The color correction device 3000 may be incorporated in a liquid crystal display device having a configuration different from that of the liquid crystal display device 1000, a display device other than the liquid crystal display device, a device other than the display device, and the like.

  The coefficient calculation unit 3026 calculates the weighting coefficients K_RGB and K_W from the primary gradation values Rin, Gin and Bin. The weighting factor K_RGB corresponds to the one-dimensional lookup tables R_LUT, G_LUT and B_LUT. The weight coefficient K_W corresponds to W_LUT(R), W_LUT(G) and W_LUT(B). The weighting factors K_RGB and K_W indicate the weights of the gradation values after the gradation conversion obtained by the gradation conversion performed according to the corresponding one-dimensional lookup table.

The gradation value calculation unit 3028 calculates the weighted sum K_RGB*R'r+K_W*R'w obtained by multiplying the secondary gradation values R'r and R'w by the weighting factors K_RGB and K_W, respectively, as the tertiary gradation value. Rout, and the weighting sums K_RGB *G'g + K_W *G'w obtained by multiplying the second-order gradation values G'g and G'w by the weighting coefficients K_RGB and K_W are set to the third-order gradation value Gout, and the weighting coefficient K_RGB And K_W are multiplied by the secondary gradation values B'b and B'w, respectively, and the weighted sum K_RGB *B'b+ K_W *B'w is set as the tertiary gradation value Bout. The third-order gradation values Rout, Gout, and Bout included in the output signal 1362 are gradation values after correction, and indicate the primary color amounts of R, G, and B, respectively.

  The smaller the weighting coefficient K_RGB, the smaller the contribution of the secondary gradation value R'r to the tertiary gradation value Rout, and the larger the weighting coefficient K_RGB, the tertiary gradation value Rout of the secondary gradation value R'r. As the weighting coefficient K_W becomes smaller, the contribution of the secondary gradation value R'w to the tertiary gradation value Rout becomes smaller, and as the weighting coefficient K_W becomes larger, the secondary gradation value R'w becomes 3 The contribution to the next gradation value Rout becomes large. Therefore, the weighting factors K_RGB and K_W represent the magnitudes of the contributions of the secondary gradation values R′r and R′w to the tertiary gradation value Rout, respectively.

  Similarly, the weighting factors K_RGB and K_W represent the magnitudes of the contributions of the secondary gradation values G'g and G'w to the tertiary gradation value Gout, respectively, and the secondary gradation values B'b and B'b and The magnitude of the contribution of B'w to the third gradation value Bout is expressed.

  Therefore, the coefficient calculation unit 3026 determines the magnitude of the contribution of each of the secondary gradation values R'r and R'w to the tertiary gradation value Rout to that represented by the weighting coefficients K_RGB and K_W, The magnitude of the contribution of each of the secondary gradation values G'g and G'w to the tertiary gradation value Gout is determined to be represented by the weighting factors K_RGB and K_W, and the secondary gradation value B'b is determined. And a deciding unit for deciding the magnitude of contribution of each of B′w to the third gradation value Bout to that represented by the weighting factors K_RGB and K_W.

  Further, in the gradation value calculation unit 3028, the degree of contribution of each of the secondary gradation values R′r and R′w to the tertiary gradation value Rout is represented by the weighting factors K_RGB and K_W. Thus, the 3rd gradation value Rout is derived from the 2nd gradation values R'r and R'w, and the contribution of the 2nd gradation values G'g and G'w to the 3rd gradation value Gout is calculated. The 3rd gradation value Gout is derived from the 2nd gradation values G'g and G'w so that the magnitude is represented by the weighting coefficients K_RGB and K_W, and the 2nd gradation values B'b and B' From the secondary gradation values B'b and B'w to the tertiary gradation value so that the magnitude of the contribution of'w to each tertiary gradation value Bout is represented by the weighting factors K_RGB and K_W. A derivation unit that derives Bout is configured.

  When the weighting factors K_RGB and K_W are calculated, the index K_W indicating the closeness of the color represented by the set of the primary gradation values Rin, Gin, and Bin to W is calculated by Expression (13).

K_W = (RGBin_MED+RGBin_MIN)/(RGBin_MAX*2) (13)

  The median value RGBin_MED is the median value of the primary gradation values Rin, Gin and Bin, and is calculated by the equation (14).

  RGBin_MED=MED(Rin,Gin,Bin) (14)

  When the color represented by the combination of the primary gradation values Rin, Gin and Bin is W, the index K_W becomes 1 because Rin=Gin=Bin, and the color is R, G or B. In some cases, two of the first-order gradation values Rin, Gin, and Bin become 0, and thus become 0, and the closer the color is to white, the larger. Therefore, the index K_W is a factor indicating the weight of W.

  Further, the index K_RGB indicating the closeness of the color represented by the combination of the primary gradation values Rin, Gin, and Bin to the single color is calculated by Expression (15).

K_RGB=1-K_W (15)
The weight coefficient K_RGB is an index obtained by subtracting the index K_W from 1, and is a factor indicating the total of the R weight, the G weight, and the B weight.

  Equations (13) to (15) are examples, and the weighting factors K_W and K_RGB may be calculated by equations different from the equations (13) to (15). For example, the weighting factors K_W and K_RGB may be calculated by the equations (16) and (17).

K_W=1-(RGBin_MAX-RGBin_MIN)/RGBin_MAX (16)
K_RGB=1-K_W (17)

  According to the third embodiment, similarly to the first embodiment, the γ characteristic is appropriately corrected for each of R, G, B, and W, the color correction is appropriately performed for W, and an arbitrary color is obtained. The color correction is properly performed for.

Further, according to the third embodiment, the γ characteristic and the color are corrected with less resources than the first embodiment.

  It should be noted that, in the present invention, the respective embodiments can be freely combined, or the respective embodiments can be appropriately modified or omitted within the scope of the invention.

  In the first to third embodiments, the liquid crystal display device has been described as an example of the display device including the color correction device of the present invention, and the embodiments have been described. However, the color correction in the present invention does not need to be performed in a specific display device, and may be performed in various display devices such as an organic electroluminescence (EL) display device and a micro electro mechanical system (MEMS) display.

  1000 liquid crystal display device, 1062 color correction unit, 1290, 2000, 3000 color correction device, 1302, 2022, 3022 primary color correction unit, 1304, 2024, 3024 white correction unit, 1306, 2026, 3026 coefficient calculation unit, 1308, 2028, 3028 gradation value calculation unit, 1322, 2042, 3042 primary color gradation conversion unit, 1342, 2062, 3062 white gradation conversion unit, 2044 calculation unit.

Claims (9)

A first one-dimensional look-up table, a second one-dimensional look-up table, and a third one-dimensional look-up table, which respectively define gradation conversion characteristics for the first primary color, the second primary color, and the third primary color. The second one-dimensional look-up table is stored by performing the gradation conversion on the first primary gradation value indicating the primary color amount of the first primary color according to the first one-dimensional look-up table. Gradation conversion is performed on the second primary gradation value indicating the primary color amount of the second primary color according to the above, and the primary color amount of the third primary color is indicated according to the third one-dimensional lookup table. A gradation conversion is performed on the third primary gradation value to obtain a first secondary gradation value indicating the primary color amount of the first primary color and a second secondary gradation value indicating the primary color amount of the second primary color. A first correction unit that obtains a next secondary tone value and a third secondary tone value indicating the primary color amount of the third primary color;
A fourth one-dimensional lookup table, a fifth one-dimensional lookup table, and a sixth one-dimensional lookup table that define gradation conversion characteristics for white are held, and according to the fourth one-dimensional lookup table. The gradation conversion is performed on the first primary gradation value, the gradation conversion is performed on the second primary gradation value according to the fifth one-dimensional lookup table, and the sixth conversion is performed. Gradation conversion is performed on the third primary gradation value in accordance with the one-dimensional look-up table, and a fourth secondary gradation value indicating the primary color amount of the first primary color, the second primary color A second correction unit that obtains a fifth secondary gradation value indicating the primary color amount and a sixth secondary gradation value indicating the primary color amount of the third primary color,
From the first primary gradation value, the second primary gradation value, and the third primary gradation value, the first secondary gradation value and the fourth secondary gradation value Determining the magnitude of the contribution to the first tertiary tone value indicating the primary color amount of each of the first primary colors to the first contribution magnitude, the second secondary tone value and the The magnitude of the contribution of each of the fifth secondary tone values to the second tertiary tone value indicating the primary color amount of the second primary color is determined to be the second contribution magnitude, and the third contribution is determined. To the third tertiary gradation value indicating the primary color amount of the third primary color of each of the secondary gradation value and the sixth secondary gradation value. And a decision unit that decides
The magnitude of the contribution of each of the first secondary grayscale value and the fourth secondary grayscale value to the first tertiary grayscale value becomes the magnitude of the first contribution. The first tertiary gradation value is derived from the first secondary gradation value and the fourth secondary gradation value, and the second secondary gradation value and the fifth secondary gradation value are derived. The second secondary gradation value and the fifth secondary gradation are set so that the magnitude of the contribution of each of the tonal values to the second tertiary gradation value becomes the magnitude of the second contribution. Deriving the second tertiary gradation value from the tonal value, and contributing each of the third secondary gradation value and the sixth secondary gradation value to the third tertiary gradation value. Deriving the third tertiary gradation value from the third secondary gradation value and the sixth secondary gradation value so that the magnitude of C is equal to the magnitude of the third contribution. When,
A color correction device including. The determining unit determines that the closer the color represented by the combination of the first primary gradation value, the second primary gradation value and the third primary gradation value is to white, the first color The contribution of the secondary gradation value of the above to the first tertiary gradation value is reduced, and the contribution of the fourth secondary gradation value to the first tertiary gradation value is increased, The contribution of the second secondary gradation value to the second tertiary gradation value is reduced, and the contribution of the fifth secondary gradation value to the second tertiary gradation value is increased. , Reducing the contribution of the third secondary gradation value to the third tertiary gradation value, and reducing the contribution of the sixth secondary gradation value to the third tertiary gradation value. The color correction device according to claim 1, wherein the size is increased. The determination unit is an index indicating the closeness of the color represented by the set of the first primary gradation value, the second primary gradation value and the third primary gradation value to white. And the closer the degree indicated by the index becomes, the smaller the contribution of the first secondary gradation value to the first tertiary gradation value becomes, and the fourth secondary gradation value becomes smaller. Of the second secondary gradation value to the second tertiary gradation value is decreased, and the contribution of the second secondary gradation value to the second tertiary gradation value is decreased. The contribution of the tonal value to the second tertiary gradation value is increased, the contribution of the third secondary gradation value to the third tertiary gradation value is decreased, and the sixth second gradation value is reduced. The color correction device according to claim 2, wherein the contribution of the next gradation value to the third tertiary gradation value is increased. The magnitude of the first contribution is represented by a first weighting coefficient and a second weighting coefficient respectively indicating weights of the first secondary gradation value and the fourth secondary gradation value,
The magnitude of the second contribution is represented by a third weighting coefficient and a fourth weighting coefficient respectively indicating weights of the second secondary gradation value and the fifth secondary gradation value,
The magnitude of the third contribution is represented by a fifth weighting coefficient and a sixth weighting coefficient respectively indicating weights of the third secondary gradation value and the sixth secondary gradation value,
The first tertiary gradation value is obtained by weighting the first secondary gradation value and the fourth secondary gradation value by the first weighting coefficient and the second weighting coefficient, respectively. It is a weighted sum of the first secondary gradation value and the fourth secondary gradation value,
In the second tertiary gradation value, the second secondary gradation value and the fifth secondary gradation value are weighted by the third weighting coefficient and the fourth weighting coefficient, respectively. A weighted sum of a second secondary gradation value and the fifth secondary gradation value,
In the third tertiary gradation value, the third secondary gradation value and the sixth secondary gradation value are weighted by the fifth weighting coefficient and the sixth weighting coefficient, respectively. 4. The color correction device according to claim 1, wherein the color correction device is a weighted sum of a third secondary gradation value and the sixth secondary gradation value. The magnitude of the first contribution is represented by a first weighting coefficient and a second weighting coefficient respectively indicating weights of the first secondary gradation value and the fourth secondary gradation value,
The magnitude of the second contribution is expressed by the first weighting coefficient and the second weighting coefficient, which respectively indicate weights of the second secondary gradation value and the fifth secondary gradation value. ,
The magnitude of the third contribution is expressed by the first weighting coefficient and the second weighting coefficient, which respectively indicate the weights of the third secondary gradation value and the sixth secondary gradation value. ,
The first tertiary gradation value is obtained by weighting the first secondary gradation value and the fourth secondary gradation value by the first weighting coefficient and the second weighting coefficient, respectively. It is a weighted sum of the first secondary gradation value and the fourth secondary gradation value,
The second tertiary gradation value is obtained by weighting the second secondary gradation value and the fifth secondary gradation value by the first weighting coefficient and the second weighting coefficient, respectively. A weighted sum of a second secondary gradation value and the fifth secondary gradation value,
In the third tertiary gradation value, the third secondary gradation value and the sixth secondary gradation value are weighted by the first weighting coefficient and the second weighting coefficient, respectively. 4. The color correction device according to claim 1, wherein the color correction device is a weighted sum of a third secondary gradation value and the sixth secondary gradation value. The first correction unit is
A gradation after the first gradation conversion indicating the primary color amount of the first primary color by performing gradation conversion on the first primary gradation value according to the first one-dimensional lookup table. A second gradation conversion indicating a primary color amount of the second primary color by obtaining a value and performing gradation conversion on the second primary gradation value according to the second one-dimensional lookup table. A third gradation indicating a primary color amount of the third primary color by obtaining a subsequent gradation value and performing gradation conversion on the third primary gradation value according to the third one-dimensional lookup table. The gradation value after the gradation conversion, and the gradation value after the first gradation conversion, the gradation value after the second gradation conversion, and the gradation value after the third gradation conversion. 6. A color according to any one of claims 1 to 5, further comprising: a gradation conversion unit for respectively converting the first secondary gradation value, the second secondary gradation value, and the third secondary gradation value. Correction device. The first correction unit is
A gradation after the first gradation conversion indicating the primary color amount of the first primary color by performing gradation conversion on the first primary gradation value according to the first one-dimensional lookup table. A second gradation conversion indicating a primary color amount of the second primary color by obtaining a value and performing gradation conversion on the second primary gradation value according to the second one-dimensional lookup table. A third gradation indicating a primary color amount of the third primary color by obtaining a subsequent gradation value and performing gradation conversion on the third primary gradation value according to the third one-dimensional lookup table. After obtaining the gradation value after the gradation conversion, the seventh one-dimensional lookup table, the eighth one-dimensional lookup table, the ninth one-dimensional lookup table, the tenth one-dimensional lookup table, the eleventh Further holding the one-dimensional look-up table and the twelfth one-dimensional look-up table, and according to the seventh one-dimensional look-up table and the eighth one-dimensional look-up table, the first primary gradation value Tone conversion after the seventh gradation conversion indicating the primary color amount of the second primary color and eighth gradation conversion indicating the primary color amount of the third primary color To obtain the gradation value of the second primary gradation value and perform gradation conversion on the second primary gradation value according to the ninth one-dimensional lookup table and the tenth one-dimensional lookup table. A gradation value after the ninth gradation conversion indicating the primary color amount of the first primary color and a gradation value after the tenth gradation conversion indicating the primary color amount of the third primary color are obtained, and the eleventh one-dimensional Eleventh gradation indicating a primary color amount of the first primary color by performing gradation conversion on the third primary gradation value according to a look-up table and the twelfth one-dimensional look-up table. A gradation conversion unit that obtains a gradation value after conversion and a twelfth gradation value after gradation conversion indicating the primary color amount of the second primary color;
The first secondary gradation is obtained by adding the gradation value after the first gradation conversion, the gradation value after the ninth gradation conversion, and the gradation value after the eleventh gradation conversion. The tone value is obtained, and the tone value after the second tone conversion, the tone value after the seventh tone conversion, and the tone value after the twelfth tone conversion are added to obtain the tone value. 2 secondary gradation value is obtained, and the gradation value after the third gradation conversion, the gradation value after the eighth gradation conversion and the gradation value after the tenth gradation conversion are added. An arithmetic unit that obtains the third secondary gradation value by combining
The color correction device according to claim 1, further comprising: A display panel having a plurality of pixels,
The color correction device according to any one of claims 1 to 7, wherein, for each of the plurality of pixels, the first primary gradation value, the second primary gradation value, and the third primary gradation value. A color correction unit that receives a gradation value and outputs the first tertiary gradation value, the second tertiary gradation value, and the third tertiary gradation value;
Driving for displaying a color represented by the set of the first tertiary gradation value, the second tertiary gradation value, and the third tertiary gradation value for each of the plurality of pixels Circuit,
A display device including. a) a first one-dimensional look-up table, a second one-dimensional look-up table and a third one-dimensional look-up table which respectively define gradation conversion characteristics of the first primary color, the second primary color and the third primary color. A table is prepared, gradation conversion is performed on a first primary gradation value indicating the primary color amount of the first primary color according to the first one-dimensional lookup table, and the second one-dimensional look-up is performed. The gradation conversion is performed on the second primary gradation value indicating the primary color amount of the second primary color according to the up table, and the primary color amount of the third primary color is calculated according to the third one-dimensional lookup table. Is converted to a first primary gradation value indicating the primary color amount of the first primary color and a second primary gradation value indicating the primary color amount of the second primary color. A second gradation value and a third secondary gradation value indicating the primary color amount of the third primary color,
b) preparing a fourth one-dimensional lookup table, a fifth one-dimensional lookup table, and a sixth one-dimensional lookup table that define white tone conversion characteristics, the fourth one-dimensional lookup table According to the fifth one-dimensional look-up table, the second primary gradation value is subjected to gradation conversion, and the first primary gradation value is subjected to gradation conversion according to the fifth one-dimensional lookup table. A gradation conversion is performed on the third primary gradation value according to a sixth one-dimensional lookup table, and a fourth secondary gradation value indicating a primary color amount of the first primary color, the second secondary gradation value, Obtaining a fifth secondary gradation value indicating the primary color amount of the primary color and a sixth secondary gradation value indicating the primary color amount of the third primary color,
c) From the first primary gradation value, the second primary gradation value and the third primary gradation value, the first secondary gradation value and the fourth secondary floor The magnitude of the contribution of each of the tonal values to the first tertiary tone value indicating the primary color amount of the first primary color is determined to be the first contribution magnitude, and the second secondary tone value is determined. And the magnitude of contribution of each of the fifth secondary tone values to the second tertiary tone value indicating the primary color amount of the second primary color is determined to be the second contribution magnitude, and A third contribution is a magnitude of contribution of each of the third secondary gradation value and the sixth secondary gradation value to the third tertiary gradation value indicating the primary color amount of the third primary color. The step of determining the size of
d) The magnitude of contribution of each of the first secondary grayscale value and the fourth secondary grayscale value to the first tertiary grayscale value becomes the magnitude of the first contribution. Thus, the first third-order gradation value is derived from the first second-order gradation value and the fourth second-order gradation value, and the second second-order gradation value and the fifth The second secondary gradation value and the fifth second gradation value are set so that the contribution of each of the next gradation values to the second tertiary gradation value becomes equal to the second contribution value. Deriving the second 3rd gradation value from the next gradation value to the 3rd 3rd gradation value of each of the 3rd 2nd gradation value and the 6th 2nd gradation value. The third tertiary gradation value is derived from the third secondary gradation value and the sixth secondary gradation value such that the contribution of the third gradation value becomes the third contribution value. Process,
A color correction method comprising:

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