JP2010286656A - Display image correction method and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To drastically reduce the number of correction data stored for three-dimensional correction. <P>SOLUTION: The image display device includes: a horizontal direction correction factor LUT (12) for storing and outputting a horizontal direction correction factor Kx corresponding to a horizontal position x; a vertical direction correction factor LUT (22) for storing and outputting a vertical direction correction factor Ky corresponding to a vertical position y; a gray level direction correction factor LUT (32) for storing and outputting a gray level direction correction factor Kp corresponding to a gamma-corrected gray level value P(z); a correction arithmetic operation unit (40) for performing correction to satisfy a three-dimensionally-corrected gray level value Q(x, y, z)=äKx(x)×Ky(y)×Kp(P(z))+1-Kp(P(z))}×(P(z)); and an image display unit (2) for displaying an image based on the three-dimensionally-corrected gray level value Q. Thus, circuit scale is reduced and adjustment man-hour for setting the correction data is drastically reduced. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a display image correction method and an image display device, and more particularly to a display image correction method and an image display device for correcting luminance unevenness and color unevenness on a screen of the display device.

  Conventionally, three-dimensional correction for correcting gradation values using correction data corresponding to the horizontal position x, vertical position y, and gradation value (signal level) z of a pixel on the screen of the display device has been performed. A technique for correcting luminance unevenness and color unevenness on the screen is known (see, for example, [0044] of Patent Document 1).

Japanese Patent Laid-Open No. 11-109927

In the prior art described above, correction data corresponding to the horizontal position x, vertical position y, and gradation value z of the pixel is stored in advance (see, for example, FIG. 7 of Patent Document 1).
However, for example, assuming that the reference horizontal position is 100 points, the reference vertical position is 75 points, and the reference gradation value is 5 points, the number of correction data to be stored is 100 × 75 × 5 = 37500. However, there is a problem that a very large memory capacity is required and the circuit configuration becomes large. In addition, there is a problem that the number of adjustment steps for setting the correction data is very large.
Accordingly, an object of the present invention is to greatly reduce the number of correction data to be stored for performing three-dimensional correction, and the circuit configuration is small, and the adjustment man-hour for setting correction data is greatly reduced. It is an object of the present invention to provide a display image correction method and an image display device that can be used.

In a first aspect, the present invention relates to a horizontal direction correction coefficient Kx (x) corresponding to a horizontal position x of a pixel in an image, a vertical direction correction coefficient Ky (y) corresponding to a vertical position y, and a gradation value z. Alternatively, a tone direction correction coefficient Kp (P) corresponding to the tone value P (z) after gamma correction is stored, and the tone value Q (x, y, z) after three-dimensional correction = {Kx (x ) × Ky (y) × Kp (P (z)) + 1−Kp (P (z))} × (P (z)).
In the display image correction method according to the first aspect, three-dimensional correction can be performed in which the gradation value is corrected by correction data corresponding to the horizontal position and vertical position of the pixel on the display screen and the gradation value. For example, assuming that the reference horizontal position is 100 points, the reference vertical position is 75 points, and the reference gradation value is 5 points, the number of correction data (= correction coefficients) to be stored is 100 + 75 + 5 = 180. As a result, the number of correction data stored for three-dimensional correction can be greatly reduced, and the circuit configuration can be reduced, and the adjustment man-hours for setting correction data in advance can be reduced. I can do it.

In a second aspect, the present invention provides the display image correction method according to the first aspect, wherein Kx = 1 and Ky = 1 at the center of the screen.
In the display image correction method according to the second aspect described above, the luminance at the center of the screen remains unchanged, which affects the calibration performed by applying a color luminance meter to the center of the screen (calibration of luminance, color, and gamma characteristics). First, the order and combination of three-dimensional correction and calibration are free.

In a third aspect, the present invention relates to a horizontal direction correction coefficient output means for storing and outputting a horizontal direction correction coefficient Kx corresponding to the horizontal position x of the pixel in the image, and a vertical direction correction coefficient Ky corresponding to the vertical position y. The vertical direction correction coefficient output means for storing and outputting, and the gradation direction correction coefficient output for storing and outputting the gradation direction correction coefficient Kp (P) corresponding to the gradation value z or the gradation value P (z) after gamma correction Means and three-dimensional corrected gradation value Q (x, y, z) = {Kx (x) × Ky (y) × Kp (P (z)) + 1−Kp (P (z))} × (P (Z)) There is provided an image display device characterized by comprising correction calculation means for performing correction calculation so as to satisfy (z)) and image display means for displaying an image based on the three-dimensional corrected gradation value Q. .
In the image display device according to the third aspect, the display image correction method according to the first aspect can be suitably implemented.

In a fourth aspect, the present invention provides the image display device according to the third aspect, wherein Kx = 1 and Ky = 1 at the center of the screen.
In the image display device according to the fourth aspect, the display image correction method according to the second aspect can be suitably implemented.

  According to the display image correction method and the image display apparatus of the present invention, the number of correction data stored for performing three-dimensional correction can be greatly reduced. As a result, the circuit configuration can be reduced, and the number of adjustment steps for setting correction data in advance can be reduced.

1 is a block diagram illustrating a configuration of an image display device according to Embodiment 1. FIG. It is a graph which illustrates horizontal direction correction coefficient Kx, vertical direction correction coefficient Ky, and gradation direction correction coefficient Kp. It is a conceptual diagram which illustrates the numerical example of the horizontal direction correction coefficient Kx, the vertical direction correction coefficient Ky, and the gradation direction correction coefficient Kp. It is a graph which illustrates the luminance change rate J (P) on the screen with respect to the gradation value P after gamma correction. It is a numerical example figure for demonstrating the setting process of the horizontal direction correction coefficient Kx and the vertical direction correction coefficient Ky. It is a numerical example figure for demonstrating the setting process of the gradation direction correction coefficient Kp. It is a graph for demonstrating the setting process of the gradation direction correction coefficient Kp. It is a numerical example figure explaining the effect of three-dimensional correction when a solid image with a gradation value of 50% is input. It is a numerical example figure explaining the effect of three-dimensional correction when a solid image with a gradation value of 75% is input. FIG. 6 is a block diagram illustrating a configuration of an image display device according to a second embodiment.

  Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the drawings. Note that the present invention is not limited thereby.

Example 1
FIG. 1 is a block diagram illustrating an image display apparatus 100 according to the first embodiment.
The image display apparatus 100 includes a gamma correction unit 1 that performs gamma correction on a gradation value z and outputs a gradation value P (z) after gamma correction, and a pixel in an image based on a horizontal synchronization signal and a clock signal. A horizontal position output circuit 11 for outputting the horizontal position x, a horizontal direction correction coefficient LUT (LookUpTable) 12 for storing and outputting a horizontal direction correction coefficient Kx corresponding to the horizontal position x, a vertical synchronization signal and a horizontal synchronization signal. The vertical position output circuit 21 for outputting the vertical position y of the pixel in the image, the vertical direction correction coefficient LUT22 for storing and outputting the vertical direction correction coefficient Ky corresponding to the vertical position y, and the gamma-corrected gradation value P (z ), And a gradation direction correction coefficient LUT32 that stores and outputs the gradation direction correction coefficient Kp corresponding to), and a three-dimensional corrected gradation value Q (x, y, z) = {Kx (x) × Ky (y) × Kp (P (z)) + 1−Kp (P (z))} × (P (z)) A correction calculator 40 that performs a correction calculation and an image based on the three-dimensional corrected gradation value Q. And an image display 2 for displaying.

FIG. 2A illustrates the horizontal direction correction coefficient Kx.
The horizontal direction correction coefficient Kx is a value of 0 ≦ Kx <2, and Kx = 1 at the horizontal position Xc in the center of the screen. As will be described later, the calculation is made from the two-dimensional luminance distribution characteristics of a display screen on which a solid screen having a specific gradation value is displayed without performing three-dimensional correction.

FIG. 2B illustrates the vertical correction coefficient Ky.
The vertical direction correction coefficient Ky is a value of 0 ≦ Ky <2, and Ky = 1 at the vertical position Yc in the center of the screen. As will be described later, the calculation is made from the two-dimensional luminance distribution characteristics of a display screen on which a solid screen having a specific gradation value is displayed without performing three-dimensional correction.

FIG. 2C illustrates the gradation direction correction coefficient Kp.
The gradation direction correction coefficient Kp is a value of about 0 to 70, and Kp = 1 for the post-gamma correction gradation value Pc = P (Zc) corresponding to the predetermined gradation value Zc. As will be described later, considering the gradation characteristics of the image display 2, the product requirement specifications, the overall image quality, etc. based on the value calculated using the luminance change rate of the screen with respect to the gradation value P after gamma correction. Decide.

FIG. 3A illustrates a numerical example of the horizontal direction correction coefficient Kx when the reference horizontal position is 5 points.
FIG. 3B illustrates a numerical example of the vertical direction correction coefficient Ky when the reference vertical position is five points.
FIG. 3C illustrates a numerical example of the gradation direction correction coefficient Kp when the reference gradation value is 5 points.

FIG. 4 is a graph illustrating the luminance change rate J (P) = ΔL / ΔP with respect to the gradation value P (z) after gamma correction. ΔP is a change in gradation value after gamma correction (or a change in gradation value after gamma correction), and ΔL is a change in luminance (or a change in luminance) with respect to ΔP.
When the gradation value P after gamma correction corresponding to the gradation value z = 50% is P (50%), J (P) = 0.96, and the gradation value P after gamma correction corresponding to the gradation value z = 75%. J (P) = 1.56 at (75%), and J (P) = 2.20 at the gradation value P (100%) after gamma correction corresponding to the gradation value z = 100%. Yes.

Next, a method for setting the horizontal direction correction coefficient Kx and the vertical direction correction coefficient Ky will be described with reference to FIG.
(1) The correction computing unit 40 is not operated, a solid image signal having a gradation value z = 50% as shown in FIG. 5A is given, and the luminance at a 5 × 5 point on the display screen is set. The luminance value obtained at the center of the screen is normalized with the luminance value obtained at the center of the screen as 100, and the luminance distribution L (x, x, 3) before three-dimensional correction as shown in FIG. y) is obtained. For simplicity of explanation, the number of points in the luminance distribution is 5 × 5, but there are actually several thousand or more.

(2) If the luminance correction amount of E% of the current luminance L is added and the luminance becomes 100%,
L (x, y) + L (x, y) × E (x, y) / 100 = 100
Therefore, if this is transformed,
E (x, y) = 100 × (100−L (x, y)) / L (x, y)
It becomes.
The required brightness correction amount E (x, y) as shown in FIG.

(3) If the gradation L after gamma correction is multiplied by K and the luminance L changes by E%, a value obtained by multiplying the difference (K-1) by the luminance change rate J (P) in FIG. I just need to be E
(K-1) * J (P) * 100 = E (x, y)
It becomes. If this is transformed,
K (x, y) = E (x, y) / (100 × J (P)) + 1
It becomes. Here, since a solid image signal having a gradation value z = 50% is given, J (P (50%)) = 0.96 from FIG.
K (x, y) = E (x, y) / 96 + 1
It becomes.
From the above equation, a provisional gamma-corrected gradation value multiplication factor K (x, y) as shown in FIG.

(4) The horizontal direction correction coefficient Kx (x) and the vertical direction correction coefficient Ky (y) are calculated from the temporary gamma-corrected gradation value multiplication factor K (x, y) by the following equation. The general notation is K (x, y), Kx (x), Ky (y), but K11 to K55, Kx1 to Kx5, and Ky1 to Ky5 are used as simple notation.
Kx1 = √ ((K11 + K12 + K13 + K14 + K15) / 5)
Kx2 = √ ((K22 + K23 + K24) / 3)
Kx3 = √ (K33)
Kx4 = √ ((K42 + K43 + K44) / 3)
Kx5 = √ ((K51 + K52 + K53 + K54 + K55) / 5)
Ky1 = √ ((K11 + K21 + K31 + K41 + K51) / 5)
Ky2 = √ ((K22 + K32 + K42) / 3)
Ky3 = √ (K33)
Ky4 = √ ((K24 + K34 + K44) / 3)
Ky5 = √ ((K15 + K25 + K35 + K45 + K55) / 5)
As shown in FIG. 5E, the above equation is such that a temporary weight value after the gamma correction at a position near the center of the screen is given a greater weight. Further, since the horizontal direction correction coefficient Kx and the vertical direction correction coefficient Ky are multiplied at the time of three-dimensional correction, each coefficient is set to a square root.
Thus, the horizontal direction correction coefficient Kx (x) and the vertical direction correction coefficient Ky (y) as shown in FIG. 5F are obtained, and the horizontal direction correction coefficient LUT12 and the vertical direction correction coefficient LUT22 are set.

(5) The gradation direction correction coefficient Kp (P) is a temporary gradation direction correction coefficient Kp ′ (P),
Kp ′ (P) = J (specific gradation value after gamma correction) / J (P)
And determine it by empirically correcting it.
For example, if a specific gradation value after gamma correction is P (50%), J (P (50%)) = 0.96 from FIG.
Kp ′ (P) = 0.96 / J (P)
Thus, a provisional gradation direction correction coefficient Kp ′ as shown in FIG. 6A is obtained.
The provisional gradation direction correction coefficient Kp ′ is corrected in consideration of the gradation characteristics of the image display device 2, the product requirement specifications of the image display device 100, the quality of the overall image quality, and the like, as shown in FIG. Is determined, and the gradation direction correction coefficient LUT32 is set.

  FIG. 7A shows the provisional gradation direction correction coefficient Kp ′, and FIG. 7B shows the gradation direction correction coefficient Kp. In the central part of the gradation value P after gamma correction (the part where the intermediate brightness is obtained), the temporary gradation direction correction coefficient Kp ′ is used as it is as the gradation direction correction coefficient Kp. The bright brightness area) has been corrected. This is because when the image display 2 is a liquid crystal panel, the tendency of display unevenness is remarkably different in the low luminance region and control is difficult, so that the correction is hardly performed, and the maximum luminance is sacrificed by the correction in the high luminance region. The amount of correction has been lowered to reduce the amount.

  In the image display device 100 in which the horizontal direction correction coefficient LUT12, the vertical direction correction coefficient LUT22, and the gradation direction correction coefficient LUT32 are set as described above, the correction arithmetic unit 40 is operated, and the floor as shown in FIG. When a solid image signal having a tone value z = 50% is given, a three-dimensional correction Q = G using a gamma-corrected tone value multiplication factor G (x, y, 50%) as shown in FIG. XP is performed. As a result, the luminance distribution as shown in FIG. 8B is obtained, and the luminance unevenness can be corrected.

  Further, when a signal of a solid image having a gradation value z = 75% as shown in FIG. 9A is given, the luminance distribution as shown in FIG. 9B is obtained before the three-dimensional correction. As a result of performing the three-dimensional correction Q = G × P using the post-gamma correction gradation value multiplication factor G (x, y, 75%) as shown in FIG. 9C, as shown in FIG. 9D. It becomes a luminance distribution, and luminance unevenness can be corrected.

According to the image display device 100 of the first embodiment, the following effects can be obtained.
(A) Brightness unevenness can be corrected. In the case of color display, color unevenness can be corrected similarly.
(B) Since the number of correction data stored for performing three-dimensional correction can be greatly reduced, the circuit configuration of the LUTs 12, 22, and 32 can be reduced, and adjustment for setting correction data is possible. Man-hours can be saved. .
(C) Conventionally, it has been necessary to measure two-dimensional luminance data for each gradation in order to set correction data. However, since it is only necessary to measure two-dimensional luminance data of one specific gradation, this point But adjustment man-hours can be saved.
(D) Since the brightness at the center of the screen remains unchanged, the periphery of the screen is corrected, so adjustment is possible independent of calibration (calibration of brightness, color, and gamma characteristics) performed by applying a color luminance meter to the center of the screen Therefore, the order and combination of brightness unevenness adjustment and calibration can be freely performed.

-Example 2-
FIG. 10 is a block diagram illustrating an image display apparatus 100 ′ according to the second embodiment.
The image display apparatus 100 ′ uses a gradation direction correction coefficient LUT 32 ′ that outputs a gradation direction correction coefficient Kp according to the gradation value z. Since the gradation value z and the gradation value P after gamma correction correspond to 1: 1, such a configuration is also possible.

-Example 3-
In the case of color display, by performing three-dimensional correction for each of R, G, and B, color unevenness can be corrected in addition to luminance unevenness correction.

  The display image correction apparatus and the image display apparatus of the present invention are particularly useful for displaying an image by correcting luminance unevenness and color unevenness of a liquid crystal panel caused by CCFL, diffusion sheet, liquid crystal application unevenness, and the like.

DESCRIPTION OF SYMBOLS 1 Gamma correction part 2 Image display 11 Horizontal position output circuit 12 Horizontal direction correction coefficient LUT
21 Vertical position output circuit 22 Vertical correction coefficient LUT
32, 32 'gradation direction correction coefficient LUT
40 Correction calculator 100, 100 'Image display device

Claims (4)

The horizontal direction correction coefficient Kx (x) corresponding to the horizontal position x of the pixel in the image, the vertical direction correction coefficient Ky (y) corresponding to the vertical position y, and the gradation value z or the gradation value P (z after gamma correction) ) And the gradation direction correction coefficient Kp (P) corresponding to the three-dimensional corrected gradation value Q (x, y, z) = {Kx (x) × Ky (y) × Kp (P (Z)) + 1-Kp (P (z))} × (P (z)). 2. The display image correction method according to claim 1, wherein Kx = 1 and Ky = 1 at the center of the screen. Horizontal direction correction coefficient output means for storing and outputting the horizontal direction correction coefficient Kx corresponding to the horizontal position x of the pixel in the image, and vertical direction correction coefficient output means for storing and outputting the vertical direction correction coefficient Ky corresponding to the vertical position y A gradation direction correction coefficient output means for storing and outputting a gradation direction correction coefficient Kp (P) corresponding to the gradation value z or the gradation value P (z) after gamma correction, and a gradation value after three-dimensional correction Q (x, y, z) = {Kx (x) × Ky (y) × Kp (P (z)) + 1−Kp (P (z))} × (P (z)) An image display device comprising: correction calculation means for performing image display; and image display means for displaying an image based on the three-dimensional corrected gradation value Q. 4. The image display device according to claim 3, wherein Kx = 1 and Ky = 1 at the center of the screen.

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