| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve problems that only one mapping curve is prepared with respect to one whole picture in conventional gradation correction using a histogram equalization method, and thereby when the gradation width of a certain gradation level range is extended, the gradation width of another gradation level range is narrowed and blackening and halation are caused. <P>SOLUTION: The local average luminance value of a local area in the picture of input image data is found out (102), the degree of backlight (202) is calculated (101) from the distribution of gradation frequencies of luminance values in the whole picture and a conversion condition for converting the gradation of the input image data is determined (103) by using the local average luminance value (204) and the backlight degree (202). <P>COPYRIGHT: (C)2007,JPO&INPIT |
