JPH11355606A - Display device and correction curve design method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily design the gamma interpolation curve of a display device. SOLUTION: This device is provided with a gamma correction curve editor 4a applied to the display device provided with a gamma correction table 1b for designing an interpolation curve passing through the points and rewriting the contents of the gamma correction table 1b while adding and moving the optional number of the points on a plane where signal strength before correction is arranged on a horizontal axis and the signal strength after the correction is arranged on a vertical axis and a luminance pattern generation part 4b for generating a uniform rectangular pattern using the signal strength V before the correction at the point during adjustment by the gamma correction curve editor 4a and a rectangular dither pattern for which the uniform rectangular pattern is binarized by using a corrected signal which has the signal strength αsmaller than the signal strength V and the corrected signal which has the signal strength β larger than the signal strength V. The rectangular pattern and the rectangular dither pattern are displayed side by side on a screen, the point is moved so as to make the luminance of the rectangular pattern equal to the luminance of the rectangular dither pattern and the interpolation curve is designed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for correcting a gamma characteristic of a liquid crystal panel in a projection display apparatus using the liquid crystal display panel, for example.

[0002]

2. Description of the Related Art A projection type display device using a liquid crystal display panel (hereinafter referred to as a liquid crystal projection type display device) is a projection type CRT.
(Cathode Ray Tube) has attracted attention as a projection-type display device that replaces the display device, and is small and lightweight, capable of displaying a large screen, and does not require color adjustment by changing the projection distance. The feature is that the projection size can be freely changed by changing the position. In a display device, in order to faithfully reproduce the color of a displayed image, the brightness of an image projected on a screen needs to have a linear characteristic with respect to an input signal level. However, both the CRT and the liquid crystal panel have non-linear characteristics as shown in FIG. 10 (conversely, the fact that the luminance of an input video signal can be reproduced as it is has linearity). This is called a gamma characteristic. Therefore,
The video signal is corrected using a curve (hereinafter, referred to as a gamma correction curve) as shown in FIG. 11 that shows the inverse characteristic of the gamma characteristic so that the entire system from the input to the output of the video signal has linear characteristics.

FIG. 9 conceptually shows the structure of a conventional liquid crystal projection display device. In FIG. 9, the liquid crystal projection display device has a signal processing circuit 1 and an optical system 2. The signal processing circuit 1 includes an analog / digital (A / D) converter 1a,
A gamma correction table 1b is provided. A / D converter 1
a indicates that the analog video signal input to the display device is red,
The image data is converted into green and blue digital video signals R, G, and B and supplied to the gamma correction table 1b. The gamma correction table 1b holds a gamma correction curve as shown in FIG. 11 for each of the digital video signals R, G, and B as a one-dimensional array on a memory. When an input signal is applied to an address pin of the memory of the gamma correction table 1b, a corrected digital video signal is output from the data pin. When the digital signal is 8 bits, it takes a value in the range of 0 to 255. The gamma correction table 1b stores the digital signals R, G,
B is supplied to the optical system 2. Each of the liquid crystal display panels 2a, 2b, and 2c of the optical system 2 outputs the digital video signals R, G, and B.
The light from the light source (not shown) is modulated in accordance with. The combining optical system 2d combines the RGB color display components obtained by light modulation into one, focuses on the screen 3, and projects and displays an image.

[0004]

In the conventional liquid crystal projection display device, a gamma-corrected image is projected and displayed on the screen 3 with the above-described configuration. Due to its characteristics, liquid crystal display panels have different gamma characteristics for each product, and often have more complicated characteristics than CRTs.
Conventionally, the gamma correction curve has been determined by trial and error such that the gamma correction curve has a linear characteristic over the entire input signal level while watching the image projected on the screen 3. As described above, since there is no design method in which a gamma correction curve is established, it is necessary to take into account the experience and intuition of a skilled designer who can accurately judge the linearity of luminance. In addition, a conventional projection display device does not include an interface capable of easily rewriting the gamma correction table, and often requires a great deal of time to design the gamma correction table.

The present invention has been made to solve such a problem, and enables a non-skilled designer to easily and quickly design a gamma correction curve for realizing linearity. The purpose is to:

[0006]

A display device according to the present invention comprises the following elements. (A) As correction information for correcting an image signal having nonlinear characteristics including at least signal strength information into an image signal having linear characteristics, signal strength information before correction and signal strength information after correction are stored in association with each other. Correction table,
(B) A plane on which the signal strength before correction and the signal strength after correction are arranged in correspondence with each other is displayed, the correction information stored in the correction table is indicated as a mark on the plane, and an arbitrary plane is displayed on the plane. A correction curve editor for adding a number mark, designing an interpolation curve passing through the added mark and the mark indicated by the correction information, and updating the correction table based on the designed interpolation curve.

Further, the display device further generates a rectangular pattern using the uncorrected signal strength V of the added mark and corrects the uncorrected signal strength α smaller than the uncorrected signal strength V. A luminance pattern generation unit that generates a binarized rectangular dither pattern using the corrected image signal and the corrected image signal having the corrected signal strength β larger than the pre-correction signal strength V.

Further, the correction curve editor moves the added mark, and designs an interpolation curve passing through the moved mark and the mark indicated by the correction information.

[0009] The luminance pattern generating section may change at least the rectangular pattern in accordance with the movement of the mark added by the correction curve editor.

[0010] The luminance pattern generating section may generate a staircase pattern for visualizing a luminance difference between signals that can be displayed on the display device.

Further, the display device further includes a focus control unit for adjusting a focus when displaying the rectangular dither pattern and the rectangular pattern generated by the luminance pattern generating unit and when displaying a video signal. It is characterized by the following.

Further, a correction curve designing method according to the present invention has the following steps. (A) As correction information for correcting an image signal having non-linear characteristics including at least signal strength information into an image signal having linear characteristics, a memory in which signal strength information before correction and signal strength information after correction are associated with each other With reference to the correction table stored in the table, a plane on which the signal strength before correction and the signal strength after correction are arranged in correspondence with each other is displayed on the screen, and the correction information stored in the correction table is marked on the plane. (B) adding an arbitrary number of marks on the plane displayed by the correction information display step, and interpolating the added mark and the mark indicated by the correction information. An interpolation curve designing step for designing a curve; and (c) a correction table updating the correction table based on the interpolation curve designed in the interpolation curve designing step. Process.

[0013] The correction curve designing method further comprises:
A rectangular pattern generating step of generating a rectangular pattern using the pre-correction signal strength V of the added mark; a corrected image signal having a pre-correction signal strength α smaller than the pre-correction signal strength V; A rectangular dither pattern generating step of generating a binarized rectangular dither pattern using a corrected image signal having a pre-correction signal strength β larger than the pre-signal strength V.

Further, the interpolation curve designing step includes a step of moving the added mark and designing an interpolation curve passing through the moved mark and the mark indicated by the correction information.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A display device and a correction curve designing method according to the present invention will be described below with reference to the drawings using a projection type liquid crystal display device as an example. Note that “gamma” in the following description is “gamma characteristic”, and “non-linear characteristic” as shown in FIG. 10 is referred to as “gamma characteristic” as described in the conventional example.

Embodiment 1 FIG. 1 shows the first embodiment.
1 shows a liquid crystal projection display device according to the first embodiment. In FIG. 1, a liquid crystal projection display device includes a signal processing circuit 1, an optical system 2,
It has a gamma curve design support unit 4, and the signal processing circuit 1 includes an analog-to-digital (A / D) conversion unit 1a and a gamma correction table 1b as a correction table. The optical system 2
Three liquid crystal display panels 2a, 2b, 2c and a synthetic optical system 2
d, a focus control unit 2e. The gamma curve design support unit 4 includes a gamma correction curve editor 4a, which is a correction curve editor, and a luminance pattern generation unit 4b.
The A / D converter 1a inputs an analog video signal having at least signal strength information having nonlinear characteristics, and converts the analog video signal into digital image signals R of red (R), green (G), and blue (B). The data is converted into G and B and supplied to the gamma correction table 1b. The gamma correction table 1b holds a gamma interpolation curve as shown in FIG. 11 for each of the digital image signals R, G, and B as a one-dimensional array on a memory. The gamma correction table 1b performs gamma correction on each of the digital image signals R, G, and B using the data stored in the memory, and supplies the data to the optical system 2. Each liquid crystal display panel 2a, 2b, 2c of the optical system 2
Modulates light from a light source (not shown) according to the digital video signals R, G, and B. The combining optical system 2d combines the RGB color display components selected by light modulation into one, and focuses and displays the image on the screen 3 by the focus control unit 2e. Gamma correction curve editor 4
In a, the horizontal axis represents the input signal strength before gamma correction and the vertical axis represents the output signal strength after gamma correction, and a graphic display is used. An arbitrary number of points are displayed on this plane using a pointing device such as a mouse. Marks, for example, points are added and moved, and an interpolation curve passing through these points is designed. The gamma correction curve editor 4a is connected to the gamma correction table 1b via a cable or the like, and converts the designed gamma curve into a conversion table that can be held in the gamma correction table 1b.
The contents of the gamma correction table 1b are rewritten.

FIG. 2 shows an outline of the processing of the gamma correction curve editor 4a. FIG. 3 is a flowchart showing a procedure for updating the gamma correction table using the gamma correction curve design method. The post-correction and pre-correction signal strength shown in FIG. 2 is an 8-bit digital signal and ranges from 0 to 255.
Take values up to. A plane in which the horizontal axis represents the input signal strength before gamma correction and the vertical axis represents the output signal strength after gamma correction shown in FIG. 2 and points 5, 6, and 7 represent the correction information display step in S1 in FIG. Is displayed. Points 5, 6, and 7 represent the corrected correction information stored in the gamma correction table 1b using points. Point 8 shown in FIG. 2 is a point added by the gamma correction curve editor 4a, and represents a point that is being corrected by operating the mouse or the like. Point 8
Can move at any position between points 6 and 7, that is, between α and β in the horizontal axis direction and between 0 and 255 in the vertical axis direction. However, at the stage of correcting the point 8, the point 6
Since point and point 7 are assumed to have been corrected, point 8 must be within a range in which luminance can be expressed using point 6 and point 7. Accordingly, a rectangular area having the points 6 and 7 as diagonals (rectangular area 10 shown by oblique lines in FIG. 2) is the effective area of point 8. As the point 8 moves, a curve passing through all the points 5 to 8 is calculated by the gamma correction curve editor 4a and redrawn. From the addition of point 8 in FIG.
Is a process executed in the interpolation curve design step of S2 in FIG. In the initial state before designing the gamma correction curve, only points 5 and 7 are located at coordinates (0, 0) and (255, 255), respectively.
The user adds points until the desired curve is obtained. This interpolation curve is converted into an array having 256 points as a set of signal strength before correction as an address and signal strength after correction as a value. This array is used as a conversion table for updating the gamma correction table 1b. The process of updating the gamma correction table based on the designed interpolation curve is shown in FIG.
This is a process executed in the correction table updating step in S3.

The luminance pattern generation section 4b generates a luminance pattern for confirming the effect of correcting the gamma correction curve designed by the gamma correction curve editor 4a, and generates a signal processing circuit 1.
Is supplied to the A / D converter 1a. A uniform rectangular pattern of the signal strength V before correction for the point being changed by the gamma correction curve editor 4a, and a corrected luminance level α having a signal value smaller than the signal strength V before correction and a signal larger than the signal strength V before correction A rectangular dither pattern binarized using the corrected luminance level β having a value is displayed side by side so that comparison can be easily performed. FIG.
9 is a flowchart showing a procedure for generating a rectangular pattern and a rectangular dither pattern. In S4 of FIG. 4, a rectangular pattern is generated by the rectangular pattern generation step using the signal intensity V before correction of the added point 8. Also, S in FIG.
At 5, the point 6 is obtained by the rectangular dither pattern generation step.
, And the uncorrected signal intensity β at point 7 (hereinafter, referred to as the luminance level α).
A binarized rectangular dither pattern is generated using the pre-correction signal intensity β (also referred to as a luminance level β). The two luminance levels α and β used in the binarization have been corrected. Therefore, the luminance processed by the gamma correction table 1b and projected on the screen 3 has a linear characteristic. Therefore, the luminance of the dither pattern using the luminance levels α and β can also be regarded as having luminance on a linear characteristic, and this dither pattern is used as reference luminance for correction. The user adjusts the position of the point 8 so that the luminance of the uniform rectangular pattern of the pre-correction signal strength V at the point 8 is equal to the luminance of the dither pattern. In this case, the horizontal axis position of the point 8, that is, the value of the signal strength before correction is
The vicinity of the midpoint between points 6 and 7 is considered to be an effective position for obtaining luminance equal to the luminance of the dither pattern. The reason for this is that the dither pattern is formed as a black and white inverted pattern, and black and white are alternately arranged near the midpoint,
This is because particles are most difficult to see. Therefore, the gamma correction curve editor 4a controls the abscissa coordinate of the newly added point to be fixed at the midpoint between two neighboring points (points 6 and 7).

When the gamma is adjusted by changing the corrected signal strength (vertical axis) while fixing the point 8 to the signal strength before correction (horizontal axis) V, the luminance of the rectangular pattern projected on the screen changes. However, since the reference rectangular dither pattern has been corrected, the luminance does not change. Therefore,
The position of the point 8 is determined so that the luminance of the rectangular pattern matches the luminance of the rectangular dither pattern. If the value of the signal intensity before correction (horizontal axis) at the point 8 is changed, the luminance of the rectangular dither pattern also changes, but the linearity is maintained. Therefore, even if the luminance of the rectangular dither pattern changes, linearity can be obtained by moving point 8 so that the luminance of the rectangular pattern becomes the same.

FIG. 5 illustrates a luminance pattern generated by the luminance pattern generation section 4b. In FIG. 5, a rectangular pattern 30 is a uniform rectangular pattern corresponding to the pre-correction signal strength V at the point 8 shown in FIG. 2 being adjusted by the gamma correction curve editor 4a. The rectangular dither pattern 31 is an enlarged image of the dither pattern obtained by binarizing the rectangular pattern of the signal strength V before correction using the signal strengths α and β before correction of the adjusted points 6 and 7. One grid represents one pixel. The grid 32 indicates pixels having a luminance α, and the grid 33 indicates pixels having a luminance β. When viewed from a distance, the rectangular dither pattern 31 looks like the same luminance as the uniform rectangular pattern 30 such as the signal strength V before correction. The position of the point 8 is adjusted by the gamma correction curve editor 4a so that the luminance of the rectangular pattern 30 in FIG. 5 looks equal to the luminance of the rectangular dither pattern 31 in FIG.

Further, the luminance pattern generation section 4b performs
Is displayed. The staircase pattern 34
The difference in luminance is visually shown for the luminance level that can be displayed on the display device. With the staircase pattern 34, the gradation characteristics of the entire signal (0 to 255) can be confirmed.

FIG. 6 schematically shows a binarizing method using the error diffusion dither method. In this method, a quantization error generated in quantization of each pixel is diffused to other pixels. FIG. 6A shows some pixels of a uniform rectangular pattern where the signal strength V before correction is “60”. Attention is paid to the pixel 9 among them. First, the pixel 9 is expressed by the equation (1) in FIG.
(2) Quantization is performed to obtain a luminance B and a quantization error E.
Assuming that the value of the pixel 9 is “60” and the luminance level α and the luminance level β are “0” and “100”, respectively, the luminance B after quantization is obtained as “100” from equation (1) in FIG. Further, the quantization error E is obtained as “−40” from the equation (2) in FIG. Next, the quantization error E is weighted and added to other pixels. The value of the weight is determined by the user based on experience.
However, the sum of the weights of the pixels is set to “1”.
FIG. 6C shows an example of the weight. In this, g
(0,0) is the pixel position being quantized, that is, pixel 9
Represents the weight of. FIG. 6E shows the coordinates of the weights corresponding to the pixel positions shown in FIG. FIG. 6 (c)
When the weight is used, the error is diffused to four neighboring pixels, and as a result, the pixel value of FIG. 6B is obtained. For example, the pixel value of the pixel 9 is such that the luminance B after quantization is “100”.
Therefore, as shown in the upper left of FIG.
0 ". The pixel to the right of pixel 9 has a weight of g
Since (1,0) = 7/16, [original luminance] 60+ [quantization error] -40 *
[Weight] 7/16 is obtained as “42.5”. Further, since the weight of the pixel located below the pixel 9 is g (0, 1) = 5/16, [original luminance] 60 + [quantization error] −40 *
[Weight] It is obtained as 47.5 from 5/16. The above processing is performed as shown in FIG.
From the pixel at the upper left corner to the pixel at the lower right corner of the rectangular pattern. When V, α, and β have the relationship of Expression (3) in FIG. 7, the pixel having the luminance of α and the pixel having the luminance of β almost have a checkerboard pattern as shown in FIG. 8B.

The dither pattern of the reference luminance generated by the luminance pattern generating section 4b looks uniform even without being affected by binarization when viewed from a sufficiently long distance. However, when projected on a large screen or near the screen, a dither pattern that should originally look the same as a rectangular pattern with uniform luminance looks different in luminance due to binarization. The focus control unit 2e controls the focus by moving the projection lens. When projecting a normal video signal, focus is set on the screen 3 to obtain a sharp video. When performing the gamma correction by projecting the correction luminance pattern generated by the luminance pattern generation unit 4b, the focus control unit 2e receives a command to generate a luminance pattern from the gamma correction curve editor 4a, and The focus on the screen 3 is reduced to blur the image. By controlling the focus and projecting the dither pattern on the screen 3 in a blurred state, the effect of binarization is removed and the dither pattern looks like a uniform rectangular pattern. FIG. 8 shows a state in which the focus control unit 2e projects the dither pattern with less focus. FIG. 8A is an image of the projected image when the focus is adjusted, and FIG. 8B is an image of the projected image when the focus is slightly reduced. The checkerboard pattern that can be clearly recognized in FIG. 8A is almost invisible in FIG. 8B and approaches a uniform rectangular pattern.

As described above, according to the present invention, in a display device having a gamma correction table capable of storing, referencing, and rewriting a gamma correction conversion table between an input digital signal and an output digital signal, the horizontal axis indicates signal intensity before correction. While adding and moving an arbitrary number of points on a plane on which the corrected signal intensity is arranged on the vertical axis, designing the interpolation curve passing through these points to create the gamma correction conversion table, A gamma correction curve editor for rewriting the contents of the gamma correction table by using the gamma correction curve editor.

The present invention also stores a gamma correction conversion table between an input digital signal and an output digital signal,
In a display device having a rewritable gamma correction table, an arbitrary number of points are added and moved on a plane having a signal strength before correction on the horizontal axis and a signal strength after correction on the vertical axis.
A gamma correction curve editor for designing the interpolation curve passing through this point to create the gamma correction conversion table and rewriting the contents of the gamma correction table; and a uniform rectangular pattern of the signal intensity V before correction of the signal to be corrected. And generate
A rectangle obtained by binarizing the rectangular pattern using a corrected signal having a pre-correction signal strength α smaller than the pre-correction signal strength V and a corrected signal having a pre-correction signal strength β larger than the pre-correction signal strength V. A gamma correction curve is designed using a luminance pattern generation unit that generates a dither pattern and generates a display signal so that the generated rectangular pattern and the rectangular dither pattern are arranged on a screen at the same time.

The luminance pattern generation section generates a staircase pattern for confirming gradation characteristics, and generates a signal for displaying the staircase pattern on a screen.

The present invention is, for example, an invention used for a projection type display device for projecting an image by using a liquid crystal panel, in which a conversion table between an input digital signal and an output digital signal is stored and can be referred to and rewritten. A gamma correction table, the gamma correction curve editor, the luminance pattern generation unit, and a focus control unit that controls the focus of an image projected on a screen.

[0028]

According to the display device of the present invention, the gamma correction curve in the gamma correction table is plotted on a graphic plane with the input signal strength before gamma correction on the horizontal axis and the output signal strength after gamma correction on the vertical axis. With a gamma correction curve editor that can automatically generate an interpolation curve passing through an arbitrary number of points added and moved on this plane using a pointing device such as a mouse, the gamma correction table can be easily created. This has the effect that the contents can be created and rewritten.

Further, in the display device of the present invention, a uniform rectangular pattern using the uncorrected signal strength V of the mark added during design by the gamma correction curve editor, and this rectangular pattern is converted from the uncorrected signal strength V A luminance pattern generation unit converts a corrected image signal having a small signal intensity α before correction and a rectangular dither pattern binarized by using a corrected image signal having a signal intensity β before correction larger than the signal intensity β before correction. To generate and project. Therefore, the amount of gamma correction can be determined by a simple operation of comparing a uniform rectangular pattern and a rectangular dither pattern, and there is an effect that even an unskilled designer can easily design a gamma correction curve.

In the display device of the present invention, when projecting the rectangular pattern and the rectangular dither pattern generated by the luminance pattern generating unit as described above, the focus control unit reduces the focus of the image on the screen. Therefore, the image is not affected by the binarization of the dither pattern even when the image is captured on a large screen or viewed from a nearby position. Therefore, there is an effect that the gamma correction curve can be more accurately designed without being affected by the surrounding environment.

Further, in the display device according to the present invention, the luminance pattern generation section generates and projects a staircase pattern for visualizing a luminance difference between signals that can be displayed on the display device. For this reason, the gamma correction amount can be determined by a simple operation of comparing a uniform rectangular pattern and a rectangular dither pattern, and the linearity can be easily checked by checking the staircase pattern. Has the effect that a gamma correction curve can be designed.

In the gamma correction curve designing method of the present invention, the correction information displaying step displays the input signal strength before gamma correction on the horizontal axis and the output signal strength after gamma correction on the vertical axis. Displaying the correction information stored in the gamma correction table as points, adding and moving an arbitrary number of points on the plane by the interpolation curve design process,
By designing an interpolation curve passing through the added points and the correction information indicated by the points, by a gamma correction table updating step,
The gamma correction table is updated based on the interpolation curve. Therefore, there is an effect that the contents of the gamma correction table can be easily created and rewritten.

Further, in the rectangular pattern generating step, a rectangular pattern is generated using the signal strength V before correction of the added point, and in the rectangular dither pattern generating step, the rectangular pattern is made smaller than the signal strength V before correction. A binarized rectangular dither pattern is generated using the corrected image signal having the pre-correction signal strength α and the corrected image signal having the pre-correction signal strength β larger than the pre-correction signal strength V. Therefore, the gamma correction amount can be determined by a simple operation of displaying a uniform rectangular pattern and a rectangular dither pattern side by side and comparing them, and there is an effect that even an unskilled designer can easily design a gamma correction curve. .

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a liquid crystal projection display device according to the present invention.

FIG. 2 is a diagram conceptually illustrating a gamma correction curve editor.

FIG. 3 is a flowchart illustrating a procedure for updating a gamma correction table using a gamma correction curve design method.

FIG. 4 is a flowchart illustrating a procedure for generating a rectangular pattern and a rectangular dither pattern.

FIG. 5 is a diagram conceptually illustrating a luminance pattern generation unit.

FIG. 6 is a diagram conceptually illustrating generation of a dither pattern using an error diffusion dither method.

FIG. 7 is a diagram showing an expression for calculating a luminance B and a quantization error E.

FIG. 8 is a diagram illustrating an effect of the focus control unit.

FIG. 9 is an explanatory diagram showing a schematic configuration of a conventional liquid crystal projection display device.

FIG. 10 is a diagram illustrating a gamma characteristic based on an inverse gamma characteristic of a display device.

FIG. 11 is a diagram illustrating gamma correction of a display device.

[Explanation of symbols]

1 signal processing circuit, 1a A / D converter, 1b gamma correction table, 2 optical system, 2a R liquid crystal panel, 2
b liquid crystal panel for G, 2c liquid crystal panel for B, 2d synthetic optical system, 2e focus control unit, 3 screen,
4 gamma curve design support section, 4a gamma correction curve editor, 4b luminance pattern generation section, 9 pixels, 10 rectangular area, 30 rectangular pattern, 31 rectangular dither pattern, 32 luminance α, 33 luminance β, 34 step pattern.

 ────────────────────────────────────────────────── ─── Continued from the front page (72) Inventor Haruhiko Nagai 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation

Claims (9)

[Claims] 1. A display device comprising the following elements: (a) as a correction information for correcting an image signal having non-linear characteristics including at least signal strength information into an image signal having linear characteristics, A correction table for storing the signal strength information and the corrected signal strength information in association with each other,
(B) A plane on which the signal strength before correction and the signal strength after correction are arranged in correspondence with each other is displayed, the correction information stored in the correction table is indicated as a mark on the plane, and an arbitrary plane is displayed on the plane. A correction curve editor for adding a number mark, designing an interpolation curve passing through the added mark and the mark indicated by the correction information, and updating the correction table based on the designed interpolation curve. 2. The display device further generates a rectangular pattern using the pre-correction signal strength V of the added mark, and corrects the pre-correction signal strength α that is smaller than the pre-correction signal strength V. A luminance pattern generating unit configured to generate a binarized rectangular dither pattern using the corrected image signal and a corrected image signal having a corrected signal strength β larger than the pre-correction signal strength V. Item 2. The display device according to Item 1. 3. The correction curve editor according to claim 1, wherein the correction mark editor moves the added mark, and designs an interpolation curve passing through the moved mark and the mark indicated by the correction information. Display device. 4. The display device according to claim 3, wherein the luminance pattern generation unit changes at least the rectangular pattern in accordance with the movement of the mark added by the correction curve editor. 5. The luminance pattern generation unit according to claim 2, wherein the luminance pattern generation unit generates a staircase pattern for visualizing a luminance difference between signals that can be displayed on the display device.
5. The display device according to 4. 6. The display device further includes a focus control unit that adjusts focus when displaying a rectangular dither pattern and a rectangular pattern generated by the luminance pattern generating unit and when displaying a video signal. The display device according to claim 2 or 4, wherein 7. A correction curve design method comprising the following steps: (a) correction information for correcting an image signal having a non-linear characteristic including at least signal strength information into an image signal having a linear characteristic; Referring to the correction table stored in the memory in correspondence with the signal strength information before correction and the signal strength information after correction, the plane on which the signal strength before correction and the signal strength after correction are arranged correspondingly is screened. And displaying the correction information stored in the correction table on the plane as a mark on the screen, and (b) placing an arbitrary number of marks on the plane displayed in the correction information display step. In addition, an interpolation curve design step of designing an interpolation curve passing through the added mark and the mark indicated by the correction information, and (c) the interpolation curve design step Correction table updating step of updating the correction table based on the interpolation curve. 8. The method for designing a correction curve further includes a rectangular pattern generating step of generating a rectangular pattern using the signal intensity V before correction of the added mark, and a pre-correction signal intensity smaller than the signal intensity V before correction. A rectangular dither pattern that generates a binarized rectangular dither pattern using a corrected image signal having a signal strength α and a corrected image signal having a pre-correction signal strength β that is greater than the pre-correction signal strength V. 8. The method according to claim 7, further comprising a generating step. 9. The interpolation curve designing step includes a step of moving the added mark and designing an interpolation curve passing through the moved mark and the mark indicated by the correction information. Or, the correction curve designing method according to 8.