Method of calculating correction value and display device

1. A method of calculating a correction value used when signal value correction is performed with respect to an image signal supplied to a display panel, the method comprising the steps of:

setting a target luminance value, which is not uniform in an overall surface of the display panel, as a target luminance value of one image signal value such that at least a portion of a distribution of target luminance values at each plane position of the display panel becomes a curved distribution; and

calculating a correction value at each plane position of the display panel using luminance observed at each plane position of the display panel when one image signal value is given to the overall surface of the display panel and the target luminance value at each plane position of the display panel.

2. The method according to claim 1 , wherein each of a plurality of representative values selected from a minimum grayscale value to a maximum grayscale value of the display panel becomes one image signal value, and the correction value at each plane position of the display panel is calculated corresponding to the image signal value as each of the representative values.

3. The method according to claim 2 , wherein the target luminance value of one image signal value at each plane position of the display panel is set so as to be distributed in a range which does not exceed a maximum luminance value observed when one image signal is given to the overall surface of the display panel.

4. The method according to claim 3 , wherein the distribution of the target luminance value of one image signal value at each plane position of the display panel becomes a curved distribution in which four corner portions of the panel have a low luminance value, as compared with the center portion of the panel.

5. The method according to claim 3 , wherein the distribution of the target luminance value of one image signal value at each plane position of the display panel becomes a curved distribution in which left and right portions of the panel have a low luminance value, as compared with the center portion of the panel.

6. The method according to claim 3 , wherein the distribution of the target luminance value of one image signal value at each plane position of the display panel has a uniform distribution area, in which the target luminance value is uniform, in a central portion of the panel, and has a curved distribution in a portion other than the central portion of the panel.

7. The method according to claim 2 , wherein the distribution of the target luminance value of one image signal value at each plane position of the display panel is set so as to become a curved distribution represented by a curve obtained by reducing a frequency of a curve of a variation in luminance value at each plane position of the display panel observed when one image signal value is given to the overall surface of the display panel.

8. The method according to claim 2 , wherein the target luminance value of one image signal value at each plane position of the display panel is set in a range in which an image signal value after the correction using the correction value does not exceed a maximum grayscale value of the display panel.

9. A display device comprising:

a display unit which performs an image display on a display panel by a supplied image signal;

a memory table unit having a plurality of reference tables respectively corresponding to a plurality of representative values as an image signal value, the reference tables each storing a correction value at each plane position of the display panel in advance; and

a correction operation unit which calculates a corrected image signal value as the image signal supplied to the display panel by an operation using an input image signal value and the correction value read from a reference table corresponding to the input image signal value in the memory table unit,

wherein the correction value stored in each of the reference tables is calculated at each plane position of the display panel using luminance observed at each plane position of the display panel when one image signal value is given to an overall surface of the display panel and a target luminance value to each plane position of the display panel, after a target luminance value which is not uniform in the overall surface of the display panel is set as a target luminance value of one image signal value such that at least a portion of a distribution of the target luminance value at each plane position of the display panel becomes a curved distribution.