JP6537401B2 - Display device and adjustment circuit for adjusting screen brightness of video signal - Google Patents

Description

  The present invention relates to a technology for adjusting the screen brightness of a video signal, and more particularly to a display device and a control circuit for performing contrast adjustment and brightness adjustment.

  Generally, in the process of acquiring an image by a camera and displaying it on a display of a display device, an optical-electro transfer function (OETF), and an electrical-signal-to-optical signal conversion (electro-optical) With transfer function (EOTF). The method of OETF in high-vision (registered trademark) broadcast imaging is described in ITU-R Recommendation BT. 709-5 (see Non-patent Document 1). On the other hand, the EOTF method for high-definition (registered trademark) broadcast imaging has a long history of using only Cathode Ray Tubes (CRTs) as a display, and being almost unique regardless of the manufacturer and model. It was not specified.

  However, the EOTF method was defined for the first time about the display characteristics of the master display used for program production in 2011, when the display was being replaced with a flat panel type such as liquid crystal, plasma, or organic EL without CRT. Reference 2).

  In the EOTF method defined by the recommendation of Non-Patent Document 2, as a function for adjusting the optimal screen luminance according to the brightness of the viewing environment, the contrast for adjusting the screen luminance gain with respect to the input video signal level And parameters of brightness to adjust the screen brightness of the reference black (adjust the reference black level).

Ｌはディスプレイの画面輝度、Ｖは入力の映像信号レベル、γはディスプレイ特性（ＣＲＴではγ＝２．４）である。ａは、画面輝度のゲインを調整するためのパラメータ（コントラストパラメータ）、ｂは、基準黒色の画面輝度を調整するためのパラメータ（ブライトネスパラメータ）である。ディスプレイ特性γ、コントラストパラメータａ及びブライトネスパラメータｂは、ユーザにより予め設定される。 In the EOTF system defined by the recommendation of Non-Patent Document 2, the screen brightness of the display is adjusted by the following equation.

L is the screen brightness of the display, V is the input video signal level, and γ is the display characteristic (γ = 2.4 for CRT). a is a parameter (contrast parameter) for adjusting the gain of the screen brightness, and b is a parameter (brightness parameter) for adjusting the screen brightness of the reference black. The display characteristic γ, the contrast parameter a and the brightness parameter b are preset by the user.

  FIG. 8 is a diagram showing display characteristics according to the EOTF method in the recommendation (ITU-R recommendation BT. 1886) of Non-Patent Document 2. As display characteristics γ = 2.4 (in the case of CRT), FIG. 8A shows that the contrast parameter a = 1.0, 2.0, 0.50 under the brightness parameter b = 0 (constant). FIG. 8 (b) shows the display characteristics when the brightness parameter b = 0, +0.025, -0.025 under the contrast parameter a = 1.0 (constant). . The horizontal axis is the video signal level V, and the vertical axis is the screen luminance L of the display.

  The display characteristics, contrast adjustment function and brightness adjustment function of the display using technology such as liquid crystal, plasma, organic EL, etc. replacing CRT, guarantee the consistency of image production and management by following the recommendation of Non-Patent Document 2. There is.

ITU-R Recommendation BT. 709-5 “Parameter values for the HDTV standards for production and international program exchange,” 2002 ITU-R Recommendation BT. 1886 “Reference electro-optical transfer function for flat panel displays used in HDTV studio production,” 2011

  In the video production in the current broadcasting system, the gray scale is represented with the video signal level of the reference black as 0% and the video signal level of the reference white as 100%. On the other hand, as a next-generation TV system, a system of Extended Image Dynamic Range TV (EIDRTV) is being studied. In the EIDRTV method, by setting the reference white video signal level to less than 100%, the high brightness component is made richer in the range from the reference white video signal level to the maximum video signal level 100% (over white area). Express in tone and color.

  Here, as shown in FIG. 8B, when the brightness parameter b is changed by the brightness adjustment, the screen brightness Lw of the reference white at the video signal level V = 1 (100%) is changed. In order to prevent the reference white screen luminance Lw from being changed, this is corrected by contrast adjustment in practical use. Specifically, after setting the optimal reference black screen brightness according to the brightness of the viewing environment by brightness adjustment, the contrast parameter a is changed by the contrast adjustment shown in FIG. The screen brightness Lw of the reference white at the signal level V = 1 (100%) is corrected.

  In the current broadcasting system, the effect of the effective brightness adjustment amount on the screen brightness Lw of the reference white is sufficiently small. This is apparent from the fact that the screen luminance L at the video signal level V = 1 (100%) in FIG. 8B does not change so much by the brightness adjustment. In order to eliminate the influence of the adjustment amount of brightness on the screen brightness Lw of the reference white, correction is performed by contrast adjustment. This will ensure the consistency of video production and management.

  On the other hand, in the EIDRTV method, the video signal level of the reference white is not 100% but less than 100%, so the effect of the effective brightness adjustment amount on the screen luminance Lw of the reference white is the current broadcast method. Larger than As shown in FIG. 8B, as the video signal level V is lowered, the screen brightness L is largely changed by the brightness adjustment, and the influence on the screen brightness Lw of the reference white is increased.

  When the EIDRTV method is used, it is desirable that the screen brightness of the reference white does not change even if the brightness parameter b is changed by the brightness adjustment, in order to guarantee consistency in image production and management.

  However, when the EOTF method prescribed by the recommendation of Non-Patent Document 2 is adopted as the EIDRTV method as it is, the screen brightness Lw of the reference white set to be less than the video signal level V = 1 (100%) by brightness adjustment. There was a problem that the

  Therefore, the present invention has been made to solve the above problems, and an object thereof is to provide a display device capable of adjusting the brightness of the reference black level so that the screen brightness of the reference white set arbitrarily does not change. It is in providing an adjustment circuit.

を満たすように、前記新たな映像信号を生成する、ことを特徴とする。 In order to solve the above problems, a display device according to claim 1 performs contrast adjustment and brightness adjustment on a video signal and displays the video signal in a display device for displaying a video, and the contrast for the video signal An adjusting unit that performs adjustment and the brightness adjustment to generate a new video signal, and outputs the new video signal as the adjusted video signal, and the video by the adjusted video signal output from the adjusting unit A display unit for displaying the display unit, the adjustment unit performs L on the screen brightness of the display in the display unit, a contrast parameter for adjusting the gain of the screen brightness a, and a brightness parameter b for adjusting the screen brightness of the reference black A video signal level of a reference white, a level of the video signal input by the adjustment unit, and a display signal of the display unit. As a ray characteristic γ, the formula

To generate the new video signal so as to satisfy the following.

を満たすように、前記新たな映像信号を生成する、ことを特徴とする。 The adjustment circuit according to claim 2 is an adjustment circuit which receives an image signal, performs contrast adjustment and brightness adjustment on the image signal, generates a new image signal, and outputs the new image signal to a display unit. In the display unit, the screen brightness of the display is L, the contrast parameter for adjusting the gain of the screen brightness is a, the brightness parameter for adjusting the screen brightness of the reference black is b, the video signal level of the reference white is r, the video signal Formula with V as the level and γ as the display characteristic of the display unit

To generate the new video signal so as to satisfy the following.

  The adjustment circuit according to claim 3 is the adjustment circuit according to claim 2, wherein the image signal is input, and the screen luminance L corresponding to the level V of the image signal is obtained by the equation. According to a conversion rule that defines a relationship between a video signal input by the display unit and a screen brightness when a video is displayed by the video signal, the screen brightness L determined by the calculating means is a video signal And converting means for converting the converted video signal as the new video signal to the display unit.

  In the adjustment circuit according to claim 4, in the adjustment circuit according to claim 2, for each group of parameters including the contrast parameter a, the brightness parameter b, the display characteristic γ, and the video signal level r of the reference white, A table in which a relationship between the video signal input by the adjustment circuit and the new video signal output by the adjustment circuit to the display unit is defined according to the equation, the video signal is input, and the table is input. And converting means for converting the video signal into the new video signal corresponding to the video signal and the parameter group, and outputting the new video signal to the display unit. I assume.

  As described above, according to the present invention, it is possible to adjust the brightness of the reference black level so that the screen brightness of the reference white set arbitrarily does not change. Therefore, consistency of video production and management using the EIDRTV scheme can be guaranteed.

It is a block diagram showing an example of composition of a display by an embodiment of the present invention. It is a figure explaining the contrast / brightness adjustment circuit by embodiment of this invention. FIG. 2 is a block diagram showing an example of the configuration of a contrast / brightness adjustment circuit according to a first embodiment. It is a block diagram showing an example of composition of operation means. FIG. 7 is a block diagram showing an example of the configuration of a contrast / brightness adjustment circuit according to a second embodiment. It is a figure explaining a table. It is a figure which shows the display characteristic by the system of EOTF in embodiment of this invention. It is a figure which shows the display characteristic by the system of EOTF in the recommendation (ITU-R recommendation BT. 1886) of a nonpatent literature 2. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is characterized in that, with respect to display adjustment according to the EOTF method in the recommendation of Non-Patent Document 2, new display adjustment is performed so that the screen brightness of the reference white becomes constant.

Display Adjustment in Embodiment of the Present Invention
The EOTF method in the embodiment of the present invention, like the EOTF method in the recommendation of Non-Patent Document 2, has an input video signal as a function for adjusting the optimal screen luminance according to the brightness of the viewing environment. It includes a contrast parameter for adjusting the screen brightness gain to the level, and a brightness parameter for adjusting the reference black level.

ｒは、基準白色の映像信号レベルであり、Ｌはディスプレイの画面輝度、Ｖは入力の映像信号レベル、γはディスプレイ特性（ＣＲＴではγ＝２．４）である。また、ａは、画面輝度のゲインを調整するためのコントラストパラメータ、ｂは、基準黒色の画面輝度を調整するためのブライトネスパラメータである。基準白色の映像信号レベルｒ、ディスプレイ特性γ、コントラストパラメータａ及びブライトネスパラメータｂは、ユーザにより予め設定される。 In the embodiment of the present invention, the screen brightness of the display is adjusted by the following equation.

r is the reference white video signal level, L is the display screen brightness, V is the input video signal level, and γ is the display characteristic (γ = 2.4 for CRT). Further, a is a contrast parameter for adjusting the gain of the screen brightness, and b is a brightness parameter for adjusting the screen brightness of the reference black. The video signal level r of the reference white, the display characteristic γ, the contrast parameter a and the brightness parameter b are preset by the user.

The formula (2) is such that the screen brightness L of the display is constant without relation to the brightness parameter b with respect to an arbitrary reference white video signal level r preset by the user. The right side of is multiplied by the following correction factor.

That is, the equation (2) can be expressed by the following equation.

前記数式（５）は、ブライトネスパラメータｂが存在しない数式であり、映像信号レベルＶが基準白色の映像信号レベルｒのときのディスプレイの画面輝度Ｌは、コントラストパラメータａ、基準白色の映像信号レベルｒ及びディスプレイ特性γにより決定されることを示している。 Here, when the video signal level V is the reference white video signal level r (when V = r), the equations (2) and (4) can be expressed by the following equations.

The equation (5) is an equation in which the brightness parameter b does not exist, and the screen brightness L of the display when the video signal level V is the reference white video signal level r is the contrast parameter a and the reference white video signal level r. And determined by the display characteristic γ.

  As described above, in the embodiment of the present invention, the screen brightness L of the display is adjusted using the equation (2). This equation (2) indicates that new display adjustment is performed by multiplying the conventional equation (1) by the correction coefficient of the equation (3) as in the equations (3) and (4). ing. By using this equation (2), the screen brightness L of the display when the video signal level V is the reference white video signal level r does not relate to the brightness parameter b as in the above equation (5). Therefore, the screen brightness of the reference white can be made constant regardless of the brightness parameter b.

  FIG. 7 is a diagram showing display characteristics according to the EOTF method in the embodiment of the present invention. As the display characteristic γ = 2.4 (in the case of CRT), FIG. 7A shows that the contrast parameter is a = 1.0, 2.0, 0.50 under the brightness parameter b = 0 (constant). Display characteristics of the contrast adjustment when the Further, FIG. 7B shows that when the brightness parameter b = 0, +0.025, −0.025 under the reference white video signal level r = 0.50 and the contrast parameter a = 1.0. The display characteristic of brightness adjustment is shown. The horizontal axis is the video signal level V, and the vertical axis is the screen luminance L of the display.

  It can be seen that the display characteristics of the contrast adjustment of FIG. 7A are similar to the display characteristics of the prior art according to Non-Patent Document 2 shown in FIG. 8A. Moreover, the display characteristic of the brightness adjustment of FIG.7 (b) differs from the display characteristic of the prior art by the nonpatent literature 2 shown in FIG.8 (b), and set the video signal level of reference | standard white to r = 0.50. In this case, it can be seen that, at the video signal level V = 0.50, the screen brightness L of the display becomes constant regardless of the brightness parameter b.

  As described above, according to the embodiment of the present invention, the screen brightness of the reference white can be made constant regardless of the brightness parameter b. That is, it is possible to adjust the brightness of the reference black level so that the screen brightness of the reference white set arbitrarily does not change. Therefore, in the case of using the EIDRTV system in which the video signal level of the reference white is less than 100% and the high luminance element is expressed with richer gradations and colors in the over white area as the broadcasting system, Consistency can be guaranteed.

[Display device]
Next, a display device according to an embodiment of the present invention will be described. FIG. 1 is a block diagram showing a configuration example of a display device according to an embodiment of the present invention. The display device 1 includes an adjustment unit 10 and a display unit 20.

  The adjustment unit 10 includes the contrast / brightness adjustment circuit 11 according to the embodiment of the present invention, and other adjustment circuits not shown. The contrast / brightness adjustment circuit 11 inputs various parameters (a contrast parameter a, a brightness parameter b, a display characteristic γ and a reference white video signal level r) preset by the user. Then, the contrast / brightness adjustment circuit 11 performs contrast adjustment and brightness adjustment on the video signal so as to satisfy the equation (2) using these various parameters. Other adjustment circuits (not shown) perform various adjustments such as luminance gamma adjustment on the video signal.

  The adjustment unit 10 inputs an image signal acquired by a camera, performs contrast adjustment and brightness adjustment by the contrast / brightness adjustment circuit 11, and adjustment by the other adjustment circuit (not shown) on the image signal, and the adjusted image A signal is output to the display unit 20. The adjustment unit 10 may input the video signal stored in the memory instead of inputting the video signal from the camera.

  The display unit 20 receives the video signal adjusted by the adjustment unit 10, and displays an image of the video signal on the screen.

[Contrast / brightness adjustment circuit 11]
Next, the contrast / brightness adjustment circuit 11 shown in FIG. 1 will be described. FIG. 2 is a diagram for explaining the contrast / brightness adjustment circuit 11 according to the embodiment of the present invention. The video signal output from the contrast / brightness adjustment circuit 11 to the display unit 20 is V ′, and the screen brightness of the video displayed by the display unit 20 is L.

  The contrast / brightness adjustment circuit 11 inputs the video signal V and uses various parameters (a contrast parameter a, a brightness parameter b, a display characteristic γ, and a reference white video signal level r) set in advance for the video signal V. The contrast adjustment and the brightness adjustment are performed in consideration of the screen luminance L of the display of the display unit 20 so as to satisfy the equation (2), and a new video signal V ′ is generated.

  The new video signal V ′ is a signal corresponding to the screen luminance L of the display calculated by the equation (2), and more specifically, the image of the screen luminance L of the display calculated by the equation (2) Is a signal for displaying on the display unit 20.

Example 1: Contrast / Brightness Adjustment Circuit 11
Next, the contrast / brightness adjustment circuit 11 of the first embodiment shown in FIG. 1 will be described in detail. FIG. 3 is a block diagram showing a configuration example of the contrast / brightness adjustment circuit 11 according to the first embodiment. The contrast / brightness adjustment circuit 11-1 includes arithmetic means 12 and conversion means 13.

  The arithmetic unit 12 inputs the video signal V and also inputs various parameters set in advance (a contrast parameter a, a brightness parameter b, a display characteristic γ and a video signal level r of a reference white). Then, the calculating means 12 calculates the screen brightness L of the display by the equation (2) using the video signal V and various parameters, and outputs this to the converting means 13 as brightness L information.

Here, in the right side of the equation (2), the portion a is the operation portion corresponding to the contrast adjustment circuit, and in the right side of the equation (2) the operation portion corresponding to the brightness adjustment circuit It is.

  The conversion means 13 receives the luminance L information from the calculation means 12 and converts the luminance L information into the video signal V 'according to the conversion rule corresponding to the display unit 20 shown in FIG. 1 and FIG. Output

  The conversion rule corresponding to the display unit 20 is preset according to the display unit 20. This conversion rule defines the relationship between the video signal (video signal V ′) input by the display unit 20 and the screen brightness (brightness L information) when the video is displayed by the input video signal. It is a rule.

  FIG. 4 is a block diagram showing a configuration example of the computing means 12 shown in FIG. The computing means 12 comprises a computing stage 16 and a correction stage 17.

  The operation stage 16 inputs the video signal V and also inputs various parameters (a contrast parameter a, a brightness parameter b, a display characteristic γ and a reference white video signal level r) set in advance. Then, using the video signal V and various parameters, the operation stage 16 uses the equation (2) that corresponds to the prior art (the equation of the first term in the right side of the The screen brightness L 'of the display is calculated by 1). The operation stage 16 outputs this as luminance L 'information to the correction stage 17.

  The correction stage 17 receives the luminance L ′ information from the operation stage 16 and also receives the brightness parameter b, the display characteristic γ and the video signal level r of the reference white among various preset parameters. Then, using the luminance L ′ information and these parameters, the correction stage 17 uses the equation (3) of the equation (3) of the equation (2) (the second equation in the right side of the equation (4)). The screen luminance L of the display is calculated according to the term equation). The correction stage 17 outputs this to the conversion means 13 as luminance L information.

  As a result, since the arithmetic stage 16 uses the mathematical formula corresponding to the conventional technology (the above-mentioned mathematical formula (1) according to the EOTF method defined by the recommendation of Non-Patent Document 2), the arithmetic processing of the prior art is used as it is The cost of implementing the embodiments of the present invention can be reduced.

  Here, in the right side of the equation (1) corresponding to the prior art by the operation stage 16, the portion a is an operation portion corresponding to the contrast adjustment circuit. Further, the part other than a on the right side of the formula (1) and the formula (3) by the correction stage 17 are calculation parts corresponding to the brightness adjustment circuit.

  As described above, according to the contrast / brightness adjustment circuit 11-1 of the first embodiment of the present invention, the computing unit 12 can execute various parameters (contrast parameter a, brightness parameter b, display characteristic γ, and video signal level of reference white) The luminance L information is obtained from the video signal V by the equation (2) using r), and the conversion means 13 converts the luminance L information into the video signal V ′ according to a predetermined conversion rule.

  Thus, when the video signal V 'is input to the display unit 20, the display unit 20 displays an image based on the luminance L of the luminance L information output from the arithmetic unit 12 on the screen. The video signal V ′ is obtained by reflecting the equation (2) on the original video signal V. As described above, the equation (2) is an equation which can make the screen brightness of the reference white constant without regard to the brightness parameter b.

  Therefore, it becomes possible to adjust the brightness of the reference black level so that the screen brightness of the reference white set arbitrarily does not change, and guaranteeing consistency of production and management of the image using the EIDRTV method it can.

Example 2 Contrast / Brightness Adjustment Circuit 11
Next, the contrast / brightness adjustment circuit 11 of the second embodiment shown in FIG. 1 will be described in detail. FIG. 5 is a block diagram showing a configuration example of the contrast / brightness adjustment circuit 11 according to the second embodiment. The contrast / brightness adjustment circuit 11-2 includes conversion means 14 and a table 15.

  The conversion means 14 inputs the video signal V and also inputs various parameters (a contrast parameter a, a brightness parameter b, a display characteristic γ and a reference white video signal level r) set in advance. Then, the conversion means 14 searches the table 15 using the video signal V and various parameters as keys, and reads the video signal V and the video signal V ′ corresponding to the various parameters from the table 15 to obtain the video signal V as a video signal. Convert to V 'and output a video signal V'.

  FIG. 6 is a diagram for explaining the table 15. This table 15 is composed of a plurality of tables for each parameter group consisting of the contrast parameter a, the brightness parameter b, the display characteristic γ and the reference white video signal level r. The relationship between the video signal V and the video signal V 'is defined in each of the plurality of tables.

  For example, in the first table, the video signal V and the video signal V ′ for the parameter group of the contrast parameter a = a1, the brightness parameter b = b1, the display characteristic γ = γ1 and the reference white video signal level r = r1 The relationship between is defined. Also, in the second table, the video signal V and the video for the parameter group of the contrast parameter a = a2 (≠ a1), the brightness parameter b = b1, the display characteristic γ = γ1 and the reference white video signal level r = r1 The relationship between the signal V 'is defined. That is, the relationship between the video signal V and the video signal V 'is defined for each table of parameter groups in which at least one of the various parameters is different.

  This table 15 uses the equation (2) for realizing the contrast / brightness adjustment circuit 11-1 shown in FIG. 3 and the conversion rule corresponding to the display unit 20 to set the video signal V for the video signal V for each of various parameters. It is generated by calculating '. That is, in the table 15, the relationship between the video signal V and the video signal V 'on which the equation (2) and the conversion rule are reflected is defined.

  Referring back to FIG. 5, specifically, the conversion unit 14 specifies one table from a plurality of tables configuring the table 15 based on various parameters set in advance. When the conversion means 14 specifies the table, when the values of various parameters set in advance are different from the values of the parameters defined in the table group of the table 15, the table with the closest two parameters is the table of the plurality of tables. Identify from inside. Then, the conversion unit 14 converts the video signal V into the video signal V ′ by reading the video signal V ′ corresponding to the video signal V from the specified table.

  As described above, according to the contrast / brightness adjustment circuit 11-2 of the second embodiment of the present invention, the conversion unit 14 reads the video signal V and the video signal V ′ corresponding to various parameters from the table 15. The video signal V is converted into a video signal V ′, and the video signal V ′ is output. In the table 15, the relationship between the video signal V and the video signal V 'on which the equation (2) and the conversion rule of the display unit 20 are reflected is defined.

  The video signal V ′ is obtained by reflecting the equation (2) on the original video signal V, and as described above, the equation (2) does not relate to the brightness parameter b, and the reference white screen is displayed. It is an equation that can make the luminance constant.

  Therefore, it becomes possible to adjust the brightness of the reference black level so that the screen brightness of the reference white set arbitrarily does not change, and guaranteeing consistency of production and management of the image using the EIDRTV method it can.

  Further, since the contrast / brightness adjustment circuit 11-2 of the second embodiment performs conversion processing using the table 15, the processing load is reduced compared to the contrast / brightness adjustment circuit 11-1 of the first embodiment which performs arithmetic processing. And the processing speed can be increased.

  The present invention has been described above by the embodiment. However, the present invention is not limited to the embodiment, and can be variously modified without departing from the technical concept thereof.

Reference Signs List 1 display device 10 adjustment unit 11 contrast / brightness adjustment circuit 12 calculation means 13 and 14 conversion means 15 table 16 calculation stage 17 correction stage 20 display unit

Claims (4)

In a display device that performs contrast adjustment and brightness adjustment on an image signal and displays the image,
An adjusting unit that receives the video signal, performs the contrast adjustment and the brightness adjustment on the video signal, generates a new video signal, and outputs the new video signal as the adjusted video signal;
And a display unit configured to display the video according to the adjusted video signal output by the adjustment unit.
The adjustment unit is
In the display unit, the screen brightness of the display is L, the contrast parameter for adjusting the gain of the screen brightness is a, the brightness parameter for adjusting the screen brightness of the reference black is b, the video signal level of the reference white is input, the adjustment unit inputs And the display characteristic of the display unit is γ.

To generate the new video signal so as to satisfy. An adjustment circuit which receives an image signal, performs contrast adjustment and brightness adjustment on the image signal, generates a new image signal, and outputs the new image signal to a display unit;
In the display unit, the screen brightness of the display is L, the contrast parameter for adjusting the gain of the screen brightness is a, the brightness parameter for adjusting the screen brightness of the reference black is b, the video signal level of the reference white is r, the level of the video signal Where V is the display characteristic of the display unit

An adjustment circuit characterized by generating the new video signal so as to satisfy. In the adjustment circuit according to claim 2,
Operation means for inputting the video signal and obtaining the screen brightness L corresponding to the level V of the video signal according to the equation;
According to a conversion rule that defines a relationship between a video signal input by the display unit and a screen brightness when a video is displayed by the video signal, the screen brightness L determined by the calculating means is a video signal Conversion means for converting the converted video signal to the display unit as the new video signal.
The adjustment circuit characterized by having. In the adjustment circuit according to claim 2,
The video signal input by the adjustment circuit and the adjustment circuit are displayed for each parameter group consisting of the contrast parameter a, the brightness parameter b, the display characteristic γ, and the video signal level r of the reference white according to the equation A table in which a relationship between the new video signal to be output to the unit and the new video signal is defined;
The video signal is input, and the video signal is converted into the new video signal corresponding to the video signal and the parameter group using the table, and the new video signal is output to the display unit Means,
The adjustment circuit characterized by having.

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