JP2005198343A - Image display unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display unit equipped with a color correction circuit capable of displaying an image which is corrected in more suitable color and has vivid and more natural color tone visually. <P>SOLUTION: The display is equipped with: an A/D conversion circuit 21; a matrix converting circuit 22; a hue converting circuit 23; a saturation converting circuit 24; a color difference converting circuit 25; an inverse matrix converting circuit 26; a signal processing circuit 1; a microcomputer 3; a display device 4; a specifc hue correction circuit 11 which controls a hue in a specific color among the image signals inputted to the signal processing circuit 1; a specific color saturation correction circuit 12 which corrects color saturation in the specific color; and a color adaptive luminance gain control circuit 14A for brightness in the specific color. Thus, the display controls brightness of the specific color in relation with control of hue of the specific color. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method and color correction circuit for optimally correcting the color of a video signal, and a video display device such as a color television receiver or a liquid crystal projector provided with such a color correction circuit.

  Currently, video sources such as DVDs, VTRs, digital broadcast tuners and personal computers are diversified. These diversified video sources are displayed on various video display devices such as a color television receiver, a plasma display panel, a liquid crystal projector, and a personal computer display. Since these video display devices have different light emission characteristics, the appearance of various shades and shades of color differs depending on the video display device, so color reproduction technology that displays video faithfully depending on the video source, video There is a need for color correction technology that adjusts the hue according to the video display device even if it is different from the actual color of the source, or dares to darken the actual video even if it is a light color or expresses a vivid color Increasingly. In addition, since there are many devices that connect video signal interfaces with digital signals in these video display devices, there is an increasing demand for realizing color reproduction and color correction by digital signal processing.

  As a conventional technique that satisfies these requirements, for example, there is a technique described in Patent Document 1 below. This is because the hue signal and saturation signal digitized from the three primary color signals are obtained, and the hue is adjusted by converting an arbitrary hue signal into a desired hue signal, and the level of the saturation signal in an arbitrary hue Is a color correction technique in which the color density is adjusted by converting a color signal into a saturation signal having a desired saturation level.

  By the way, in the above-described prior art, it is possible to freely adjust the hue and shade of the color by adjusting an arbitrary hue and an arbitrary saturation, but such color correction is performed depending on the color. However, there is a problem that the appearance on the video display device cannot always be corrected to a suitable color.

  Hereinafter, as an example, an image of a landscape such as a lawn or a tree will be described. The color correction of the yellowish green part of the lawn will be described. First, it is assumed that the hue is adjusted so as to control the fresh green by changing the hue of the yellow-green part of the lawn, or that the saturation level is amplified so that the color of the lawn becomes darker. . In performing this control, there have been the following problems in controlling the saturation level. That is, when the color is controlled to be dark, in a dominant color such as lawn where the brightness level is relatively high, green is emphasized and the color is displayed darker, but at the same time, the visual brightness appears to increase more. As a result, the saturation gradation seems to have deteriorated, and it has become too bright, resulting in a slightly unnatural calm green grass. In addition, in dark green tree leaves, etc., with a relatively low brightness level, the color becomes darker due to saturation enhancement. There was a problem that appeared to deteriorate.

  In this way, by enhancing the saturation, the overall vivid coloration is enriched. However, when the image is observed all over the details, the color of the image and its color, as in the case of the lawn, etc. described above. Depending on the brightness of the image, even if the color is darker at high brightness levels, it may display an unnaturally bright image, or conversely, at low brightness levels such as in the case of tree leaves. There is a problem that the color correction cannot be suitably performed for the user, such as the color of the portion where the saturation enhancement is performed becomes dark and the color of the portion looks dark visually.

JP 2001-125557 A

  The present invention has been made in view of the above-described problems, and a color correction method capable of displaying an image having a visually vivid and more natural color tone by correcting to a more suitable color and It is an object of the present invention to provide a color correction circuit and a video display device including such a color correction circuit.

  In order to achieve the above object, according to the present invention, in the video display device, specific hue control means for controlling the hue of a specific color in the input video signal and brightness in the specific color of the input video signal are obtained. Specific color luminance control means for controlling is provided, and the brightness of the specific color is controlled in association with the control of the hue of the specific color.

  In order to achieve the above object, according to the present invention, in the video display device, a specific color saturation control means for gain-controlling the saturation level of a specific color in the input video signal, and the saturation gain control is performed. Signal processing means including brightness control means for controlling the brightness of the video signal is provided.

  Specifically, the signal processing means includes an AD converter that converts an input video signal into a digital signal, and a matrix conversion circuit that converts the digital signal output from the AD converter into a luminance signal and at least two color difference signals. A color conversion circuit for obtaining a hue signal from the color difference signal output from the matrix conversion circuit, a saturation conversion circuit for obtaining a saturation signal from the color difference signal, and a microcomputer, and the color luminance The control means performs signal processing for controlling the gain and direct current level of the luminance signal based on the set value of the predetermined hue range supplied from the microcomputer.

  The luminance control means is constituted by a signal processing circuit including a multiplier for controlling the gain of the luminance signal or an adder for changing the direct current level of the luminance signal.

  The color correction method according to the present invention includes a step of converting an input video signal into a digital signal, a step of separating the digital signal into a luminance signal and a color difference signal, and converting the color difference signal into a hue signal and a saturation signal. And a step of controlling a gain of a saturation signal in a specific hue from the hue signal, and a step of varying a brightness included in an image gained from the saturation signal. .

  According to the configuration of the present invention, since the brightness of the color is changed by controlling the luminance signal included in the video signal subjected to the saturation correction, for example, a bright green color such as lawn. Even if the image is mainly yellowish green, the brightness can be slightly reduced even if the color is controlled deeper by enhancing the saturation, so that the color can be deepened and natural and clearer. Green can be achieved. In this way, it is possible to provide an image that can be corrected and reproduced in a more beautiful color with respect to a bright color.

  According to the present invention, it is possible to suitably correct the hue and saturation in a desired video signal. In particular, since gain control of the luminance signal included when performing saturation enhancement can be performed, natural color correction with depth can be performed, and there is an effect that suitable color correction can be easily performed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The configuration of the signal processing circuit used in the video display apparatus according to the first embodiment of the present invention will be described with reference to the block diagram of FIG.

  The video display device includes a signal processing circuit 1A, an A / D conversion circuit 21, a matrix conversion circuit 22, a hue conversion circuit 23, a saturation conversion circuit 24, a color difference conversion circuit 25, and an inverse matrix conversion circuit 26. And a microcomputer (hereinafter referred to as a microcomputer) 3 and a display device 4.

  The signal processing circuit 1A has a function of controlling the luminance of a specific color in the input video signal, and includes a specific hue correction circuit 11, a specific saturation correction circuit 12, an adder 13, and a color adaptive luminance. A gain control circuit 14 </ b> A and a multiplier 15 are included.

  The color adaptive luminance gain control circuit 14 includes a luminance comparison circuit 141, a hue comparison circuit 142, and a luminance gain control circuit 143.

  The A / D conversion circuit 21 has an R input terminal T21R to which an R primary color signal is input, a G input terminal T21G to which a G primary color signal is input, and a B input terminal T21B to which a B primary color signal is input. The input analog primary color signal is converted into a digital primary color signal signal.

  The matrix conversion circuit 22 performs matrix conversion processing on the digital primary color signals (R, G, B) input from the A / D conversion circuit 21 to obtain a luminance signal Y and a color difference signal (R−Y) signal. And (BY) signals are output. The luminance signal Y is output to the color adaptive luminance gain control circuit 14A and the multiplier 15. Both the (R−Y) signal and the (B−Y) signal are output to the hue conversion circuit 23 and the saturation conversion circuit 24.

  The hue conversion circuit 23 uses the (R−Y) signal and the (B−Y) signal input from the matrix conversion circuit 22, for example, performs an attribute conversion operation as shown in the following equation 1 to perform a digital hue. The signal θ is output.

彩度変換回路２４は、マトリクス変換回路２２から入力された（Ｒ−Ｙ）信号と（Ｂ−Ｙ）信号を用いて、例えば下記数２式に示すような属性変換演算をしてデジタル形式の彩度信号Ｓを出力する。

The saturation conversion circuit 24 uses the (R−Y) signal and the (B−Y) signal input from the matrix conversion circuit 22 to perform an attribute conversion operation as shown in the following equation 2, for example, in a digital format. A saturation signal S is output.

色差変換回路２５は、信号処理回路１の特定色相補正回路１１で補正された色相信号と特定彩度補正回路１２で補正された彩度信号が入力され、（Ｒ−Ｙ）’と（Ｂ−Ｙ）’の色差信号に変換して逆マトリクス変換回路２６へ出力する。

The color difference conversion circuit 25 receives the hue signal corrected by the specific hue correction circuit 11 of the signal processing circuit 1 and the saturation signal corrected by the specific saturation correction circuit 12, and inputs (R−Y) ′ and (B−). Y) 'is converted into a color difference signal and output to the inverse matrix conversion circuit 26.

  The inverse matrix conversion circuit 26 performs color correction on the luminance signal Y ′ subjected to luminance control and the color difference signal (RY) ′ and the color difference signal (BY) ′ on which hue correction and saturation correction have been performed. The signals are converted into R, G, and B primary color signals and output to the display device 4. The video display device 4 displays a video that has been color-corrected based on the three primary color signals.

  The R primary color signal, G primary color signal, and B primary color signal supplied to the A / D conversion circuit 21 via the R input terminal T21R, the G input terminal T21G, and the B input terminal T21B are converted into digital signals, respectively, and matrix conversion is performed. It is output to the circuit 22. The matrix conversion circuit 22 performs matrix conversion processing on the digital primary color signals (R, G, B) output from the A / D conversion circuit 21, and generates a luminance signal Y and a color difference signal from the digital three primary color signals. It converts into (R−Y) signal and (B−Y) signal and outputs. This luminance signal Y is output to the color adaptive luminance gain control circuit 14. Further, the (R−Y) signal and the (B−Y) signal, which are color difference signals, are output to the hue conversion circuit 23 and the saturation conversion circuit 24, respectively.

  Here, the hue signal and the saturation signal will be described with reference to FIG. As shown in FIG. 2, when the horizontal axis represents the (BY) signal, the vertical axis represents the (RY) signal, and the vertical axis (not shown) represents the luminance (brightness), the color is Expressed as a vector. The direction of the vector (the angle formed by the (BY) axis which is the horizontal axis and the vector) indicates the hue θ which is a hue, and the magnitude of the vector indicates the saturation S which is the color shading. In this way, a vector display of colors is called a hue circle and is generally known.

  In this hue circle, for example, magenta is represented by a vector located at an angle of 45 ° from the (BY) axis, as shown in FIG. That is, the magenta hue θ is 45 °. The saturation S is determined by the size of the vector. The larger the vector size, the darker the color, and the smaller the color, the lighter the color. If the vector size is 0, it indicates that there is no color. The hues of red, yellow, green, cyan, and blue are 113.2 °, 173.0 °, 225.0 °, 293.2 °, and 353.0 °, respectively.

  The hue conversion circuit 23 outputs a hue signal in a digital format. If the bit accuracy of the digital signal is 10 bits, the hue conversion circuit 23 outputs a hue of 0 ° to 359.9 ° as a digital signal of 0 to 1023. That is, the hue 360 ° is divided by 1024 which is the power of 2, and 1LSB of the hue digital signal is about 0.35 °.

  The contents described above will be supplemented using FIG. FIG. 3 is a diagram showing an example of the relationship between the hue signal and the saturation signal as a waveform A, where the horizontal axis represents the hue signal θ (10-bit accuracy) and the vertical axis represents the saturation signal S (8-bit accuracy). Yes. Also, representative hues (B−Y) are shown as 0, (R−Y) as 256, − (B−Y) as 512, and − (R−Y) as 768.

  On the other hand, the saturation conversion circuit 24 outputs a saturation signal S having a color vector corresponding to the hue signals 0 to 1023 as a digital signal. When the bit accuracy of the digital saturation signal is 8 bits, the saturation conversion circuit 24 outputs a digital signal of 0 to 255.

  The digital hue signal θ output from the hue conversion circuit 23 is input to the specific hue correction circuit 11 of the signal processing circuit 1A. The specific hue correction circuit 11 adjusts the hue by correcting and outputting a hue signal in a specific hue range of the input digital hue signal θ. The hue range and correction amount of the hue signal θ corrected by the specific hue correction circuit 11 are determined by various setting values output from the microcomputer 3.

  Details of the configuration and operation of the specific hue correction circuit 11 will be described with reference to FIGS. 4, 5, and 6. FIG. 4 is a block diagram showing a specific configuration of the specific hue correction circuit 11. The specific hue correction circuit 11 includes an adder 111, a local hue correction circuit 112, a hue signal input terminal T111, a hue range setting signal input terminal T112, and a corrected hue signal output terminal T113. .

  When the specific hue correction circuit 11 does not add the correction signal to the digital hue signal θ input by the adder 111, the specific hue correction circuit 11 is a linear output in which the input is output as it is, as indicated by the straight line B in FIG. It shall have input / output characteristics. The digital hue signal θ output from the hue conversion circuit 23 is input to the adder 111 and the local hue correction circuit 112 via the hue signal input terminal T111. In the local hue correction circuit 112, the hue center value (HP shown in FIG. 5B), the level (H shown in FIG. 5B), the level (H shown in FIG. 5B), and the hue width (FIG. 5), which are hue range setting signals. 5) is input via the hue range setting signal input terminal T112, and the hue within this hue range is decoded based on these values, as shown by the waveform C in FIG. 5B. A signal with a trapezoidal waveform is output.

  The adder 111 adds the digital hue signal θ and the output signal of the local hue correction circuit 112 having the trapezoidal waveform C. As a result, as shown in FIG. 6A, the output of the adder 111 outputs a signal having a waveform D that is shifted by H upward in the W section centered on HP. This shift (control) amount is determined by the level H input from the microcomputer 3.

  The operation of the above-described hue correction will be described by taking the above-described lawn image as an example. When the hue range is designated as a yellow-green hue and the shift amount is added to this color, the yellow-green hue is shown in FIG. The hue is controlled in the green direction (counterclockwise) of the hue circle shown in FIG. As described above, the specific hue correction circuit 11 variably controls the hue within the range specified by the microcomputer 3 at the level specified by the microcomputer, so that the hue can be controlled locally. .

  Further, the output signal (waveform D) of the adder 111 is input to one input terminal of the adder 13 via the output terminal T113. The offset value output from the microcomputer 3 is input to the other input terminal of the adder 13. This offset value has a constant value a over the entire hue as shown by a straight line E in FIG. The adder 13 adds the signal D output from the specific hue correction circuit 11 and the offset value a output from the microcomputer 3. As a result, the adder 13 outputs a signal obtained by shifting the entire signal shown in FIG. 6A upward (offset) by the offset value a as shown by the waveform F in FIG. As described above, the adder 13 can control the overall hue (over all hues). This is a function corresponding to so-called tint adjustment, and is used when it is desired to adjust the overall hue.

  In the first embodiment of the present invention, a 10-bit adder is used for both input and output as the adder 13, and therefore when the addition result exceeds 1023, it overflows and returns to 0. Therefore, when the addition result exceeds 1023, the adder 13 outputs a value obtained by subtracting 1023 from the addition result.

  As described above, the specific hue correction circuit 11 can change the hue signal in the hue range designated by the microcomputer 3 to another hue. For example, even for a yellow-green image such as lawn, the hue shift control is performed so that a specific hue in the specified hue range is shifted counterclockwise so that it is away from the yellow component and becomes pure green. Can do. Further, by setting the adder 13 so as to add the offset, it is possible to output a signal in which the entire hue is offset by a predetermined value, so that the overall hue can be adjusted.

  Here, since the digital signal having the bit accuracy of the hue signal of 10 bits is used, highly accurate hue shift control and hue offset control in units of about 0.35 degrees can be performed. Further, parameters related to hue correction, such as hue shift amount H, shift range W, and offset amount a, are set by the microcomputer 3, so that these parameters can be arbitrarily changed and adjusted.

  In this embodiment, the range of hue shift is set to one. However, a plurality of local hue correction circuits 112 are prepared, and parameters for hue correction are set independently by the microcomputer 3, and these local hue correction circuits 112 are set. It is also possible to independently shift (control) a plurality of hues by adding all of the output signals to the adder 13. Then, the color-corrected hue signal θ ′ from the adder 13 is input to the color difference conversion circuit 25.

  On the other hand, the digital saturation signal S output from the saturation conversion circuit 24 is input to the specific saturation correction circuit 12. The digital hue signal θ output from the hue conversion circuit 23 is also input to the specific saturation correction circuit 12. The specific saturation correction circuit 12 adjusts the color shade by correcting the saturation signal in a specific hue range of the input digital saturation signal S and adjusting the saturation gain. The hue range (saturation gain control range) and the correction amount of the saturation signal corrected by the specific saturation correction circuit 12 are determined by various setting values output from the microcomputer 3.

  Details of the configuration and operation of the specific saturation correction circuit 12 will be described with reference to FIGS. FIG. 7 is a block diagram illustrating a specific circuit configuration example of the specific saturation correction circuit 12. The specific saturation correction circuit 12 includes a multiplier 121, a local saturation correction circuit 122, an adder 123, a saturation signal input terminal T121, a hue signal input terminal T122, and a hue range setting signal input terminal T123. And a post-correction saturation signal output terminal T124.

  The specific saturation correction circuit 12 adds nothing to the digital saturation signal in the adder 123 and does not multiply anything in the multiplier 121 (when the gain is set to 1), as shown in FIG. It is assumed that the input and output characteristics are such that the input is output as it is, as indicated by the straight line G. The digital saturation signal S output from the saturation conversion circuit 24 is input to one of the multipliers 121 through the saturation signal input terminal T121 of the specific saturation correction circuit 12. The digital hue signal θ output from the hue conversion circuit 23 is input to the local saturation correction circuit 122 via the hue signal input terminal T122.

  In the local saturation correction circuit 122, the hue center value (HP shown in FIG. 8B), the level (SH shown in FIG. 8B), the hue width (FIG. W) shown in b) is input, a hue within this range is decoded from the digital hue signal based on these values, and a specific range having a trapezoidal waveform as shown by waveform H in FIG. A saturation correction signal H for locally correcting the saturation in the hue of. The adder 123 adds the offset value (default value is 128) output from the microcomputer 3 and the output signal H of the local saturation correction circuit 122. As a result, as shown in the waveform I of FIG. 8C, the adder 123 shifts by SH above the W section with the HP as the center, and the saturation amplification coefficient having a characteristic offset as a whole by the offset value. I is output. Therefore, it is the height SH that determines the amplification degree of the saturation signal in the specific hue range, and the amplification degree of the entire saturation signal (saturation signal in all hues) is determined by the offset value from the microcomputer 3. .

  This offset value is constant over the entire hue, and the level is 128 in the present embodiment, which is intermediate between the minimum value (0) and the maximum value (255) of the saturation signal (8-bit accuracy). Is set. The output signal (saturation amplification coefficient I) of the adder 123 is input to the other input terminal of the multiplier 121, and the multiplier 121 outputs the digital saturation signal output from the saturation conversion circuit 24 previously input to the other. Multiply by S. By multiplying the digital saturation signal S by the saturation amplification coefficient I, a saturation signal S ′ whose gain in the saturation of the specific hue range is gain-controlled is output from the output terminal T124.

  As described above, the specific saturation correction circuit 12 can variably control the color density by locally correcting the saturation signal in the specified hue range and controlling the saturation gain in the specific hue. In this embodiment, the color to be corrected by the specific saturation correction circuit 12 is yellowish green, but the hue correction from yellow green to green is performed by the specific hue correction circuit 11 described above, and as a result, the green saturation is enhanced. Will be. For example, a yellow-green image such as a lawn can be darkened by controlling the gain of the saturation level to enhance the color.

  Here, in the specific hue correction circuit 11 described above, assuming that the lawn yellow-green color is corrected to pure green as exemplified in the above example, the specific saturation correction circuit 12 performs hue correction to pure green. Since the saturation is corrected with respect to the selected color, the color of the lawn is corrected to an image in which a pure green color is corrected deeply. Further, the saturation signal of all hues can be controlled by the adder 123 which is a component of the specific saturation correction circuit 12 to variably control the color shading in all hues, which corresponds to so-called color adjustment. It is a function.

  Further, since the microcomputer 3 sets parameters for saturation correction, such as the saturation correction amount SH, the correction range W, and the offset amount, these parameters can be arbitrarily changed and adjusted.

  In the first embodiment, the saturation correction range is one. However, a plurality of local saturation correction circuits 122 are prepared, and the parameters related to the saturation gain are set by the microcomputer 3 independently of each other. It is also possible to independently correct the saturation in a plurality of hue ranges by adding all the outputs of the above and inputting them to the adder 123.

  The saturation signal S ′ output from the specific saturation correction circuit 12 is input to the other input of the color difference conversion circuit 25. Then, the color difference conversion circuit 25 converts the saturation signal S ′ and the hue signal θ ′ described above into a color difference signal (RY) ′ and a color difference signal (BY) ′, and outputs them to the inverse matrix conversion circuit 26. .

  The color adaptive luminance gain control circuit 14A described below is a main feature of the present invention, and is a circuit that controls the gain of a luminance signal included in an image that has been subjected to saturation gain control by the specific saturation correction circuit 12. . The color adaptive luminance gain control circuit 14A includes a luminance comparison circuit 141, a hue comparison circuit 142, and a luminance gain control circuit 143.

  Hereinafter, the operation of the color adaptive luminance gain control circuit 14A will be described with reference to FIG. FIG. 9 shows the characteristics of each part constituting the color adaptive luminance gain control circuit 14A.

  The luminance signal Y output from the matrix conversion circuit 22 is input to one input terminal of the luminance comparison circuit 141. The luminance threshold value YL output from the microcomputer 3 is input to the other input terminal of the luminance comparison circuit 141. In the luminance comparison circuit 141, the luminance threshold value YL and the luminance signal Y are compared in level. FIG. 9A shows the input / output characteristics of the luminance comparison circuit 141. The horizontal axis represents the input luminance signal Y, and the vertical axis represents the output flag signal YF. On the horizontal axis of the luminance signal Y, the luminance threshold value YL input from the microcomputer 3 is shown. The luminance comparison circuit 141 outputs a flag signal “1” if the level of the luminance signal Y is larger than the luminance threshold YL, as shown by the waveform J in FIG. If it is smaller than the luminance threshold YL, a flag signal “0” is output. The luminance threshold value YL can be set to a desired value by the microcomputer 3.

  The digital hue signal θ output from the hue conversion circuit 23 is input to one input terminal of the hue comparison circuit 142. A hue range value θW output from the microcomputer 3 is input to the other input terminal of the hue comparison circuit 142. As the hue range value θW, the same information as the hue designation information (HP and W shown in FIG. 8B) designated by the microcomputer 3 in the specific saturation correction circuit 12 can be designated. The hue comparison circuit 142 compares and detects whether or not the input hue signal θ is a value θW within the hue range designated by the microcomputer 3. FIG. 9B shows the input / output characteristics of the hue comparison circuit 142, where the horizontal axis represents the input hue signal θ and the vertical axis represents the output match flag signal θF. On the horizontal axis of the hue signal θ, the hue range set by the microcomputer 3 is shown. As shown by the waveform K in FIG. 9B, the hue comparison circuit 142 outputs a match flag signal “1” if the value θW is within the hue range, and outputs a match flag signal “0” if they do not match. To do.

  The flag signal YF output from the luminance comparison circuit 141 and the match flag signal θF output from the hue comparison circuit 142 are input to the luminance gain control circuit 143, respectively. Further, the luminance gain control value YGC output from the microcomputer 3 is input to the luminance gain control circuit 143 and set. The luminance gain control circuit 143 outputs a luminance gain signal controlled as described below, and this luminance gain signal is input to the multiplier 15. A waveform L in FIG. 9C shows the input / output characteristics of the luminance gain control circuit 143. The horizontal axis represents the luminance signal Y, and the vertical axis represents the luminance gain signal (YGAIN) as an output. The luminance gain control circuit 143 shows input / output characteristics when the flag signal YF output from the luminance comparison circuit 141 is “1” and the match flag signal θF output from the hue comparison circuit 142 is “1”. At this time, a gain A is output. Note that the value of the gain A is the luminance gain control value YGC from the microcomputer 3 described above, and can be set to a desired value. Here, it is assumed that the gain A is set to a value smaller than 1 and 0.9. Further, when the flag condition is not described above, that is, when either one of the flag signal YF output from the luminance comparison circuit 141 or the coincidence flag signal θF output from the hue comparison circuit 142 is “0”. The luminance gain control circuit 143 outputs a gain 1 (waveform L shown in FIG. 9C). In this way, the luminance gain control circuit 143 can generate a binary luminance gain signal YGAIN (1 or A) with the luminance threshold YL of the luminance signal Y in the specified color as a boundary.

  The luminance gain signal YGAIN output from the luminance gain control circuit 143 is input to the multiplier 15, and the luminance signal Y output from the matrix conversion circuit 22 is multiplied by the luminance gain signal YGAIN. If the threshold YL or less, the gain is 1, so the luminance signal Y is output as it is, and if the threshold YL or more is the gain A (= 0.9), the amplitude level of the luminance signal Y is controlled to be small. The controlled luminance signal Y ′ is output.

  In the lawn example described above, the green color of the lawn whose hue has been corrected by the specific hue correction circuit 11 and whose saturation has been corrected by the specific saturation correction circuit 12 is included in the yellow-green image of the lawn before the hue correction and saturation correction. Since the level of the luminance signal to be transmitted is quite high, the luminance signal is quite bright. For this reason, the color adaptive luminance gain control circuit 14A can control the image portion of the lawn to have a high saturation and to reduce the level of the green luminance signal, so that the luminance can be reduced by appropriately reducing the luminance. The color can be corrected to green with a natural depth.

  Here, the hue comparison circuit 142, which is a component of the color adaptive luminance gain control circuit 14A, does not necessarily perform the luminance gain control as described above for the color on which the saturation saturation control is performed by the specific saturation correction circuit 12. It is not necessary to perform this, and the color for which the luminance gain control is performed can be designated via the microcomputer 3 so that the luminance gain is controlled only for a specific color, for example, a yellow-green portion such as a lawn. . In addition, the luminance comparison circuit 141 is provided as a component of the color adaptive luminance gain control circuit 14, but the hue comparison circuit 142 limits the hue range as much as possible to limit the color to a high luminance level only. Since the color adaptive luminance gain control circuit 14 can be realized, the function of the luminance comparison circuit 141 is not necessarily required.

  Further, the luminance gain control circuit 143 does not have the binary gain characteristics as shown in FIG. 9C, but as shown in the waveform M above the luminance threshold YL as shown in FIG. May be provided with a downward-sloping slope characteristic that lowers the luminance gain YG as the luminance signal level increases. As a result, there is an effect that the luminance can be suppressed in a portion where the input luminance is higher depending on the video.

  Further, two or more luminance threshold values YL are specified in the luminance comparison circuit 141 and a plurality of flag signals for identifying luminance levels of three or more values are provided, and the luminance gain control circuit 143 provides three or more. A luminance gain signal having a luminance gain control value may be generated.

  In this way, the gain-controlled luminance signal Y ′ is input to the inverse matrix conversion circuit 26 together with the color difference signals (RY) ′ and (BY) ′ output from the color difference conversion circuit 25, and is subjected to an inverse matrix conversion process. Is converted into R, G, and B primary color signals. The three primary color signals output from the inverse matrix conversion circuit 26 are supplied to the video display device 4, and the video display device 4 displays a video that has been color-corrected based on the three primary color signals.

  As described above, in the first embodiment, the gain of the luminance signal included in the video signal for which the saturation gain control is performed can be controlled. Therefore, as in the above-described example of the video, the lawn Even in a video mainly composed of yellowish green with a relatively high luminance level, even if gain control is performed by increasing the saturation and darkening the color, it can be controlled to decrease the luminance gain, so that the natural depth There is an effect that an image corrected in color can be displayed.

  In addition, brightness gain control can be performed optimally for a specified color, so brightness control can be performed without affecting the brightness of other colors, and suitable color correction can be easily performed. There is an effect that can be performed.

  Further, when controlling the saturation gain of a specific color, it is not always necessary to perform luminance gain control, and the specific saturation gain control and the luminance gain control can be controlled independently of each other. Depending on the color, it is also possible to control the gain of only the luminance signal included in the designated color without performing the saturation gain control, and such a control method is also included in the first embodiment. Needless to say. In addition, the microcomputer can freely set the brightness threshold value YL, the hue width θW, etc., and these controls can adjust the control level for any color.

  The outline of the configuration of the signal processing circuit used in the video display apparatus according to the second embodiment of the present invention will be described with reference to FIG. In the second embodiment shown in FIG. 11, blocks having the same functions as those of the first embodiment shown in FIG. In the second embodiment, an adder 16 is used in place of the multiplier 15, and a color in which a luminance DC control circuit 144 is provided in place of the color adaptive luminance gain control circuit 14A including the luminance gain control circuit 143. The difference from the first embodiment is that the adaptive luminance DC control circuit 14B is used.

  The flag signal YF output from the luminance comparison circuit 141 and the match flag signal θF output from the hue comparison circuit 142 are input to the luminance DC control circuit 144, respectively. Further, the microcomputer 3 outputs a luminance offset YO value, which will be described later, to the luminance DC control circuit 144.

  The characteristics of the output signal of the luminance DC control circuit 144 will be described with reference to FIG. In the figure, the horizontal axis represents the luminance signal Y input to the color adaptive luminance DC control circuit 14B, the vertical axis represents the luminance offset signal YOFFSET, which is the output signal of the luminance DC control circuit 144, and the vertical axis -B represents the microcomputer 3 The luminance offset YO value input from is shown. Hereinafter, the operation of the luminance DC control circuit 144 will be described with reference to FIG.

  In the luminance DC control circuit 144, the flag signal YF output from the luminance comparison circuit 141 is “1” (indicating a pixel in a luminance signal larger than the luminance threshold YL), and the match flag signal θF output from the hue comparison circuit 142 is “ Only when 1 ″ (indicating a pixel in the hue signal of the specified color), as shown in FIG. 12, an offset amount equal to the luminance offset YO value is generated in the luminance offset signal (YOFFSET) as the output signal. When both flag signals are not “1”, the default value “0” is output as the luminance offset signal YOFFSET. The luminance offset YO value can be set to a desired value by the microcomputer 3. Now, the luminance offset YO value is set to a negative value (here, assumed to be −B).

  Next, the operation of the adder 16 will be described. First, the luminance offset signal (YOFFSET) is input to one input terminal of the adder 16. On the other hand, the luminance signal Y output from the matrix conversion circuit 22 is input to the other input terminal of the adder 16. The adder 16 adds the luminance signal Y and the luminance offset signal (YOFFSET). In this way, the adder 16 has a luminance signal obtained by lowering the direct current level of the luminance signal included in the video for controlling the saturation gain of the specific color by YOFFSET (−B). Can be output.

In the same manner as in the above-described example, the lawn will be described as an example. The brightness DC control circuit 144 can control the lawn image portion to have a high brightness and to reduce the direct current level of the brightness signal included in the green picture.

  As described above, in the second embodiment, since the DC level of the luminance signal included in the video signal for which the saturation gain control is performed can be controlled, the video described in the above example is used. In addition, even if the image is mainly composed of yellowish green with a relatively high brightness level of the lawn, it is possible to control the gain to increase the saturation and gain the color darkly, and to reduce the brightness brightness slightly. As in the first embodiment, since the brightness can be moderately suppressed, there is an effect that a natural and fresh image with more vividness and deep color can be displayed.

  The configuration of the signal processing circuit used in the video display apparatus according to the third embodiment of the present invention will be described with reference to FIG. In the description of the third embodiment, blocks having the same functions as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In the third embodiment, a saturation gain control circuit 145 is newly added to the color adaptive luminance gain control circuit 14A to obtain a color adaptive luminance saturation gain control circuit 14C, and the output of the specific saturation correction circuit 12 2 is different from the first embodiment in that a multiplier 17 is newly provided.

  First, the saturation gain control circuit 145 that is a component of the color adaptive luminance saturation gain control circuit 14C will be described. The flag signal YF output from the luminance comparison circuit 141 and the match flag signal θF output from the hue comparison circuit 142 are input to the saturation gain control circuit 145, respectively. Further, the microcomputer 3 inputs a saturation gain control value SGC described later to the saturation gain control circuit 145. In the saturation gain control circuit 145, the flag signal YF output from the luminance comparison circuit 141 is “0” (the pixel in the luminance signal equal to or lower than the luminance threshold YL), and the match flag signal θF output from the hue comparison circuit 142 is “1”. Only when “(pixel in the hue signal of the specified color)”, the gain “C” is output to the saturation gain signal SG as the output signal as shown in FIG. The value of the gain “C” is the saturation gain control value SGC input by the microcomputer 3 and can be set to a desired value. Here, the gain “C” is set to a value smaller than “1”. When both flag signals are not in the condition described above, SG = “1” is output as the saturation gain of the default value. As described above, the saturation gain control circuit 145 can obtain the saturation gain P in which the saturation gain of the low luminance portion with the luminance threshold value YL as the boundary is varied as shown in FIG.

  As described above, in the present embodiment, after the saturation gain of a specific color is controlled at a constant gain by the specific saturation correction circuit 12, the multiplier 17 uses the saturation gain signal SG to adjust the saturation in the low luminance portion. Since the gain of the signal S ′ can be lowered, in addition to the effects described in the first embodiment, the specific saturation is controlled darkly by the specific saturation correction circuit 12, and the gradation is deteriorated. Even in the color in the low-luminance part, there is an effect that the brightness can be adjusted to the optimum brightness visually.

  Further, the saturation gain in the low luminance portion is not controlled as in the characteristics shown in FIG. 14A, but the luminance gain control circuit 143 as shown in the waveform Q in FIG. 14B. It is also possible to obtain the same effect as described above by varying the luminance gain of the low luminance portion with the luminance threshold YL as a boundary. The luminance gain control circuit 143 controls to increase the gain of low luminance with respect to the color in which the saturation gain of the specific color is controlled at a constant gain by the specific saturation correction circuit 12 (see FIG. 14B). “D”). As a result, the brightness of the low-brightness portion that appears to be dark visually by controlling the specific color deeply by the specific saturation correction circuit 12 can be adjusted to increase the brightness and become brighter. In addition to the effects of the above embodiments, there is an effect that the brightness of low luminance can be adjusted similarly.

  The configuration of the signal processing circuit used in the video display apparatus according to the fourth embodiment of the present invention will be described with reference to FIG. In the fourth embodiment, blocks having the same functions as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The fourth embodiment is different from the first embodiment in that a signal processing circuit 1D is provided by newly providing a luminance nonlinear correction circuit 18 in the signal processing circuit 1A.

  The luminance nonlinear correction circuit 18 variably controls the amplitude level and DC level of the luminance signal Y separated from the input video signal by the matrix conversion circuit 22, and FIG. 16 shows a detailed circuit diagram thereof. The luminance nonlinear correction circuit 18 includes a black extension circuit 181, a white extension circuit 182, a multiplier 183, a clip circuit 184, an adder 185, and a clip circuit 186, and a maximum / minimum value detection circuit. 112 is provided. Further, the luminance nonlinear correction circuit 18 includes a luminance signal input terminal T181 to which a luminance signal Y is input, a YBK input terminal T182 to which a black expansion upper limit setting value YBK and a gain coefficient are input, a white expansion lower limit setting value YWT and a gain. YWT input terminal T183 to which a coefficient is input, contrast control coefficient input terminal T184 to which a contrast control coefficient is input, DC level input terminal T185 to which a DC level signal is input, and maximum value / minimum value detection signal output terminal T186 And a luminance signal output terminal T187.

  The luminance signal Y output from the matrix conversion circuit 22 is supplied to one input terminal of the black expansion circuit 181 via the luminance signal input terminal T181. The other input terminal of the black expansion circuit 181 is supplied with the black expansion upper limit set value YBK and the gain coefficient set by the microcomputer 3 via the YBK input terminal T182. The black expansion circuit 181 variably controls and outputs the luminance amplitude of the luminance signal equal to or less than the black expansion upper limit setting value YBK, and supplies it to one input terminal of the white expansion circuit 182.

  The other input terminal of the white extension circuit 182 is supplied with the white extension lower limit set value YWT and gain coefficient set by the microcomputer 3 via the YWT input terminal T183. The white expansion circuit 182 variably controls the luminance amplitude of the luminance signal equal to or greater than the white expansion lower limit setting value YWT and outputs the luminance signal. The luminance signal whose amplitude is controlled by the white expansion circuit 182 is supplied to the multiplier 183.

  The multiplier 183 multiplies this luminance signal by the contrast control coefficient input from the microcomputer 3 via the contrast control coefficient input terminal T184 to variably control the amplitude (contrast control).

  When an overflow occurs in the output signal from the multiplier 183, the clip circuit 184 clips the overflow with the upper limit value (maximum value 255 with 8-bit accuracy) and outputs the result. This output signal is input to the adder 185.

  The adder 185 adds the output signal and the direct current (DC) value input from the microcomputer 3 via the direct current level input terminal T185 to perform brightness control.

  When an overflow occurs in the output signal from the adder 185, the clip circuit 186 clips the overflow with an upper limit value (maximum value 255 with 8-bit accuracy). The output signal of the clip circuit 186 is output to the inverse matrix conversion circuit 26 via the luminance output terminal T187.

  The maximum value / minimum value detection control circuit 187 detects the maximum level and the minimum level of the luminance signal Y before the luminance correction input via the luminance signal input terminal T181, and sets the maximum / minimum value detection signal output terminal T186. To the microcomputer 3.

  Based on the detected maximum level and minimum level, the microcomputer 3 determines the black expansion upper limit setting value YBK and the gain coefficient input to the black expansion circuit 181 and the white expansion lower limit setting value YWT input to the white expansion circuit 182. And the gain coefficient, the contrast control coefficient input to the multiplier 183, and the direct current level input to the adder 185 are determined by calculation.

  FIG. 17 is a diagram for supplementarily explaining the operation of the luminance nonlinear correction circuit 18 described above, and shows input / output characteristics of each part of the luminance nonlinear correction circuit 18. A waveform R in FIG. 17A shows input / output characteristics when nothing is corrected by the luminance nonlinear correction circuit 18, and shows a case where the luminance signal Y inputted from the luminance signal input terminal T181 is outputted as it is. A waveform S in FIG. 17B shows an output signal in which the black portion and the white portion are expanded by the black expansion circuit 181 and the white expansion circuit 182. In the waveform S, the portion processed by the black expansion circuit 181 is a solid line portion whose gain is adjusted below the set value YBK level, and the portion processed by the white expansion circuit 182 is the gain adjustment above the set value YWT level. It is the part of the solid line made. A waveform T in FIG. 17C shows a signal when the luminance input signal is subjected to contrast control processing by the multiplier 183 and the clip circuit 184 (in FIG. 17C, for simplicity of illustration). The black and white stretches are shown as not being done). A waveform U in FIG. 17D shows a signal when the waveform R is subjected to brightness control processing by the adder 185 and the clip circuit 186 (in FIG. 17D, for simplicity of illustration). Black stretch, white stretch, and contrast control are shown as not being performed).

  As described above, in the present embodiment, brightness control (contrast control) and DC level control (brightness control) are performed on the luminance signal Y, and gradation control of the high-level luminance signal Y is enhanced (white expansion). Control) and emphasis control (black expansion control) of the gradation of the low-level luminance signal. As a result, a sharp tone-rich luminance signal (hereinafter referred to as a corrected luminance signal) can be obtained. Since the corrected luminance signal corrected nonlinearly in this way is input to the multiplier 15 and the color adaptive luminance gain control circuit 14D, saturation gain control and luminance gain control are performed for a specific color. be able to. Therefore, there is an effect that color correction can be corrected more optimally even for a video display apparatus in which image quality is better when luminance correction is performed.

  Although the details of the color correction signal processing circuit including the luminance gain control according to the present invention have been described above, this signal processing circuit is used for a direct-view television receiver or a rear projection television receiver. The present invention can also be applied to a display device for a computer monitor. Furthermore, as a display device of a video display device provided with this signal processing circuit, not only a cathode ray tube but also a liquid crystal panel, a plasma display panel (PDP), or the like can be used. That is, according to the present invention, the above-described effects can be obtained even if display devices having different light emission characteristics are used. In addition, various parameters relating to hue correction and saturation correction (for example, luminance lower limit setting value YL) may be appropriately changed by the microcomputer 3 in accordance with the type of display device (various characteristics such as color reproduction and luminance saturation). Is preferred. It goes without saying that such embodiments are also included in the present invention.

The block diagram explaining the structure of the signal processing circuit used for the video display apparatus concerning the 1st Embodiment of this invention. The figure explaining the hue circle which represented the color with the vector. The figure explaining an example of the relationship between a hue signal and a saturation signal. The block diagram explaining the detailed structure of a specific hue correction circuit. The figure explaining the characteristic of each part of a specific hue correction circuit. The figure explaining the characteristic of each part of a specific hue correction circuit. The block diagram explaining the detailed structure of a specific saturation correction circuit. The figure explaining the characteristic of each part of a specific saturation correction circuit. The figure explaining the characteristic of each part of a color adaptive luminance gain control circuit. The figure explaining an example of the gain control characteristic of a color adaptive brightness | luminance gain control circuit. The block diagram explaining the structure of the signal processing circuit used for the video display apparatus concerning the 2nd Embodiment of this invention. The figure explaining the characteristic of the output signal of a brightness | luminance DC control circuit. The block diagram explaining the structure of the signal processing circuit used for the video display apparatus concerning the 3rd Embodiment of this invention. FIG. 14 is a diagram illustrating characteristics of each unit in FIG. 13. The block diagram explaining the structure of the signal processing circuit used for the video display apparatus concerning the 4th Embodiment of this invention. The block diagram explaining the detailed structure of a brightness | luminance nonlinear correction circuit. The figure explaining the input-output characteristic of each part of a brightness | luminance nonlinear correction circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A, 1B, 1C, 1D ... Signal processing circuit, 11 ... Specific hue correction circuit, 111 ... Adder, 112 ... Local color correction circuit, 12 ... Specific saturation correction circuit, 121 ... Multiplier, 122 ... Local saturation correction Circuit 123... Adder 13... Adder 14 A color adaptive luminance gain control circuit 14 B color adaptive luminance DC control circuit 14 C color adaptive luminance saturation gain control circuit 14 D color adaptive luminance gain control circuit 141 ... Luminance comparison circuit, 142 ... Hue comparison circuit, 143 ... Luminance gain control circuit, 144 ... Luminance DC control circuit, 145 ... Saturation gain control circuit, 15 ... Multiplier, 16 ... Adder, 17 ... Multiplier, 18 ... brightness non-linear correction circuit, 181 ... black extension circuit, 182 ... white extension circuit, 183 ... multiplier, 184 ... clip circuit, 185 ... adder, 186 ... clip circuit, 187 ... maximum value / minimum value detection control circuit T21R ... R primary color signal input terminal, T21G ... G primary color signal input terminal, T21B ... B primary color signal input terminal, 21 ... AD conversion circuit, 22 ... Matrix conversion circuit, 23 ... Hue conversion circuit, 24 ... Saturation conversion circuit, 25 ... color difference conversion circuit, 26 ... inverse matrix conversion circuit, 3 ... microcomputer, 4 ... video display device.

Claims (24)

  Among the input video signals, a specific hue control means for controlling the hue of a specific color and a specific color luminance control means for controlling the brightness of the specific color are provided, and the brightness of the specific color is related to the control of the hue of the specific color. A video display device characterized by controlling the thickness.   Among the input video signals, specific color saturation control means for controlling the gain of the saturation signal in a specific color, and brightness control of a specific color included in the video signal whose saturation gain is controlled by the specific color saturation control means An image display device comprising specific color luminance control means for performing   The specific color saturation control means is a means for enhancing a saturation level by increasing a gain of a saturation signal of a specific color among the input video signals, and the specific color luminance control means is the specific color saturation control. 3. The video display device according to claim 2, wherein the video display device is luminance gain control means for controlling the gain of the luminance signal contained in the video in which the level of the saturation signal from the means is emphasized to be small.   The specific color saturation control means is a means for controlling the gain of the saturation level of a specific color in the input video signal, and the specific color luminance control means is a video whose saturation gain is controlled by the specific color saturation control means. 3. The video display device according to claim 2, wherein the video display device is luminance direct current level control means for controlling the direct current level of the luminance signal included in the signal to be lowered. A hue conversion circuit that obtains a hue signal from an input video signal, a saturation conversion circuit that obtains a saturation signal from the video signal, and a hue signal in which the hue value of a specific color is varied from the hue signal obtained from the hue conversion circuit A specific hue control circuit for obtaining a saturation signal in which the gain of the saturation signal in a specific hue is controlled from the hue signal obtained from the hue conversion circuit and the saturation signal obtained from the saturation conversion circuit In a video display device configured with a degree control circuit,
An image display apparatus comprising: a specific color luminance control means for controlling a luminance signal included in an image for controlling a gain of a saturation signal in the specific color saturation control circuit. An AD converter for converting the input video signal into a digital signal, a matrix conversion circuit for converting the digital signal output from the AD converter into a luminance signal and at least two color difference signals, and an output from the matrix conversion circuit A hue conversion circuit that obtains a hue signal from a hue difference signal, a saturation conversion circuit that obtains a saturation signal from the hue difference signal, and a hue signal in which the hue value of a specific color is varied from the hue signal obtained by the hue conversion circuit A specific color saturation control circuit, and a specific color saturation control circuit for obtaining a saturation signal in which the saturation level of the specific hue is varied from the hue signal obtained by the hue conversion circuit and the saturation signal obtained by the saturation conversion circuit. In a video display device configured to include:
An image display apparatus comprising: a specific color luminance control means for controlling a luminance signal including a color for gain control of a saturation level in the specific color saturation control circuit.   7. The video display device according to claim 2, wherein the specific color luminance control means includes luminance gain control means for controlling a gain of a luminance signal.   7. The video display device according to claim 2, wherein the specific color luminance control means includes luminance direct current level control means for controlling a direct current level of the luminance signal. .   8. The video display according to claim 3, wherein the luminance gain control means includes a multiplication circuit that varies an amplitude level based on a pedestal level of the luminance signal. apparatus.   9. The video display device according to claim 3, wherein the luminance direct current level control means includes an adding circuit or a subtracting circuit that varies the direct current level of the luminance signal. .   The luminance gain control means detects a predetermined hue from the hue signal obtained by the hue conversion circuit and obtains a flag signal, and generates a luminance gain control signal from the flag signal obtained by the hue comparison circuit. A brightness gain control circuit; and a multiplication circuit that obtains a gain-controlled brightness signal by multiplying the brightness gain control signal obtained by the brightness gain control circuit and the brightness signal obtained from the matrix conversion circuit. The video display device according to claim 3 or 7.   The luminance gain control means detects a predetermined hue from a luminance comparison circuit that obtains a flag signal by comparing the luminance signal obtained by the matrix conversion circuit with a predetermined level, and a hue signal obtained by the hue conversion circuit. A hue comparison circuit for obtaining a flag signal, a luminance gain control circuit for generating a luminance gain control signal from the flag signal obtained by the luminance comparison circuit and the flag signal obtained by the hue comparison circuit, and the luminance gain control circuit The video display device according to claim 3, further comprising: a multiplication circuit that obtains a gain-controlled luminance signal by multiplying the gain control signal and the luminance signal. The luminance level control means detects a predetermined hue from the hue signal obtained by the hue conversion circuit and obtains a flag signal, and generates a luminance level control signal from the flag signal obtained by the hue comparison circuit. A luminance gain control circuit; and an addition circuit for obtaining a luminance signal whose luminance level is controlled by multiplying the luminance level control signal obtained from the luminance gain control circuit by the luminance signal obtained by the matrix conversion circuit. The video display device according to claim 4 or 7.   The luminance level control means detects a predetermined hue from a luminance comparison circuit that obtains a flag signal by comparing the luminance signal obtained by the matrix conversion circuit with a predetermined level, and a hue signal obtained by the hue conversion circuit. A hue comparison circuit that obtains a flag signal, a luminance level control signal generation circuit that generates a luminance level control signal from the flag signal obtained by the luminance comparison circuit and the flag signal obtained by the hue comparison circuit, and the luminance level control signal generation 8. The video display according to claim 4, further comprising an addition circuit for obtaining a luminance signal whose luminance level is controlled by adding the luminance level control signal obtained by the circuit and the luminance signal. apparatus.   Non-linear luminance signal control means for detecting the information of the luminance signal to nonlinearly control the gain in the luminance signal and controlling the DC level, and using the luminance signal obtained by the non-linear luminance signal control means, the luminance control means The video display apparatus according to claim 1, wherein the luminance control is performed by the control.   The non-linear luminance signal control means includes a black expansion circuit that controls the amplitude of a black signal having a predetermined black luminance or less in the luminance signal, a white expansion circuit that controls the amplitude of a white signal having a predetermined white luminance or higher, and the white expansion circuit 16. The video display device according to claim 15, further comprising: a contrast control circuit that controls the amplitude of the output signal; and a brightness control circuit that controls a DC level of the output signal of the contrast control circuit.   A luminance gain control method, comprising: controlling brightness of a specific color in association with control of a hue of a specific color in an input video signal.   A luminance level control method, comprising: controlling a direct current level of a luminance signal corresponding to a specific color among input video signals.   A method of performing gain control of saturation of a specific color with respect to an input video signal, and controlling the gain of a luminance signal included in the video signal when performing gain control of saturation of the input video signal And a color correction method.   A method of performing gain control of saturation of a specific color with respect to an input video signal, wherein a DC level of a luminance signal included in the video signal is controlled when performing gain control of saturation of the input video signal. A color correction method characterized by controlling.   A method of performing gain control of saturation of a specific color with respect to an input video signal, wherein a DC level of a luminance signal included in the video signal is controlled when performing gain control of saturation of the input video signal. A color correction method characterized by controlling.   A method for emphasizing the saturation level of a specific color with respect to an input video signal, wherein the gain of a luminance signal included in the video signal is controlled when performing control to increase the saturation gain of the input video signal. A color correction method characterized by controlling to lower.   A method for emphasizing a saturation level of a specific color with respect to an input video signal, and of the input video signal, a direct current level of a luminance signal included in the video signal when performing control to increase a saturation gain A color correction method characterized by controlling to lower the color. A method of performing color correction on an input video signal, the step of converting the input video signal into a digital signal, the step of separating the digital signal into a luminance signal and a color difference signal, and the color difference signal as a hue signal Converting to a saturation signal, controlling a gain of a saturation level in a specified hue signal among the hue signals, and controlling a gain of a luminance signal included in the color whose saturation level gain is controlled. And a color correction processing method.

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