| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent gradation correction from becoming unnatural by local property distortion or inclination change that is specific to equalizing of histograms. <P>SOLUTION: The gradation correction apparatus for converting gradations of an original image comprises a histogram creating part, a first property creating part, a second property creating part, a property compositing part, and a gradation correcting part. The histogram creating part creates a histogram from lightness of the original image. The first property creating part finds a first gradation conversion property for making approximately equal fineness and coarseness of probability densities of the histogram. The second property creating part holds a second gradation conversion property limited to a gradation change, wherein a gradation skip does not occur. The characteristic compositing part performs weighted compositing of the first gradation conversion property and the second gradation conversion property, to create a composited gradation conversion characteristics. The gradation correcting part finds the ratio of input/output gradations of the composited gradation conversion characteristics, using the lightness as an input parameter and multiplies the color components of the source image with this ratio to correct the gradations of the original image. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
