Method and apparatus for acquiring luminance information and for evaluating the quality of a display device image

A method of evaluating the image quality of a display device comprising the steps of:

• subdividing a photographed image into a plurality of pixels;
• calculating a first luminance value as a difference between the sum of luminance values of predetermined pixels and the luminance value of a predetermined pixel, said predetermined pixels forming a first pixel group surrounding said predetermined pixel, said first luminance value calculation providing local luminance unevenness information;
• calculating a second luminance value as a difference between a sum of luminance values of predetermined pixels forming a second pixel group and the luminance value of said predetermined pixel, said predetermined pixels surrounding said predetermined pixel being positioned farther away from said predetermined pixel than pixels from said first pixel group, said second luminance calculation providing luminance unevenness information of the entire photographed image;
• obtaining a third luminance value based on said first luminance value and said second luminance value, said third luminance providing a double peripheral difference;
• and
• evaluating the luminance of said photographed screen based on said third luminance value to determine an acceptable level of quality.

An apparatus of acquiring luminance information of a display device, wherein the luminance information of an image displayed on the display device is acquired, comprising:

• photographic means for photographing the image displayed on said display device;
• image processing means for dividing image data relating to the image photographed by said photographic means;
• and
• operation means for executing operation processing represented by equation (1) for the image data subdivided by said image processing means, wherein equation (1) is represented by:
• A(x,y)=[pi−/(x,y)] (1)
• wherein p represents luminance values of pixels forming a pixel group surrounding a pixel at a position of said image data defined by (x, y), and l(x, y) represents a luminance value of the pixel at the position defined by (x, y) of said image data.

An apparatus of evaluating image quality of a display device, wherein the quality of an image displayed on the display device is evaluated, comprising:

• photographic means for photographing the image displayed on said display device;
• image processing means for dividing image data relating to the image photographed by said photographic means;
• and
• operation means for executing operation processing represented by equation (2) for the entire image data divided by said image processing means and for quantifying the photographed image based on P(x, y) as luminance data obtained by said operation processing, wherein equation (2) being represented by:
• A(x,y)=[Σpi −/(x,y] (1)
• where
• are luminance values of pixels forming a first pixel group arranged linearly in a symmetrical form with respect to a position of said image data defined by (x, y),
• po are luminance values of pixels constituting a second pixel group forming a linearly symmetrical form with respect to the position of said image data defined by (x, y), said second pixel group being located outside of said first pixel group, wherein
• I(x, y) is the luminance value of a pixel at the position defined by (x, y) of said image, and
• a, b, c are coefficients either 0 or a positive number.