| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problem that, in conventional gray level correction, when a gray level width of a certain gray level range is widened, a gray level width of another gray level range is narrowed to cause a saturated gray level. <P>SOLUTION: The gray level correction apparatus comprises: a local average luminance calculation unit 102 which divides a picture of an input image into a plurality of local regions B and determines a local average luminance value (a) for each of the plurality of local regions; a backlight level calculation unit 101 which calculates a backlight level (g) from the distribution of gray level frequency of luminance values in the entire picture of the input image; and a gray level conversion unit 103 which determines a conversion condition for converting the gray level of the input image using the local average luminance value (a) and the backlight level (g) and uses the determined conversion condition to perform gray level conversion in the input image. Regarding the conversion condition, in the local region B where the local average luminance value (a) is smaller than a predetermined value, a luminance value is changed to increase luminance in the local region. In a local region where the local average luminance value (a) is greater than the predetermined value, a luminance value is changed to decrease luminance in the local region. As a value of the backlight level (g) is great, a change amount of the luminance value is enlarged. <P>COPYRIGHT: (C)2009,JPO&INPIT |
