Color-unevenness inspection apparatus and method

1. A color-unevenness inspection apparatus comprising:

an image pickup section to pick up an image of an inspection target in a color-unevenness inspection;

an image generation section to generate an uneven-color image by, in the picked-up image of the inspection target obtained by the image pickup section, calculating a chroma in each unit region and identifying an uneven-color region based at least in part on a magnitude of the calculated chroma;

a calculation section to calculate, for the uneven-color region in the uneven-color image, an evaluation parameter to be used in the color-unevenness inspection; and

an inspection section to perform the color-unevenness inspection based at least in part on the calculated evaluation parameter,

wherein the image generation section calculates the chroma, in each unit region of the picked-up image, while performing correction processing that reflects variations in color-unevenness visibility from color to color,

wherein as the evaluation parameter, the color-unevenness inspection apparatus uses an uneven-color area ratio that is an area ratio of an uneven-color region to an entire region of the inspection target, and a maximum chroma in an entire region of the uneven-color region.

2. The color-unevenness inspection apparatus according to claim 1 , wherein the image generation section calculates values (a*, b*) in a CIELAB color space, in each unit region of the picked-up image, and

the image generation section performs, as correction processing that reflects variations in color-unevenness visibility from color to color, gain correction processing expressed by equation (1) on the calculated value a*, and calculates a chroma C by using equation (2):

a *′=(α× a *) (when a*> 0:gain α>1, when a*≦ 0:gain α=1)  (1)

C ={( a* ′) 2 +( b *) 2 } 1/2   (2).

3. The color-unevenness inspection apparatus according to claim 1 , wherein the inspection section performs the color-unevenness inspection based at least in part on a comprehensive evaluation value obtained through weighting and addition of the uneven-color area ratio and a maximum chroma.

4. The color-unevenness inspection apparatus according to claim 3 , wherein the inspection section determines that

the larger the comprehensive evaluation value, the larger a degree of color unevenness in the inspection target, and

the smaller the comprehensive evaluation value, the smaller the degree of color unevenness in the inspection target.

5. The color-unevenness inspection apparatus according to claim 2 , wherein the inspection target is a display screen in a display device that displays a color image.