Patent ID: 7391903

Claim:
An image processing method for converting a first image, which is expressed in a colorimetric system made up of a plurality of color components and is constituted of a plurality of pixels each holding color information corresponding to a single color component, to a second image constituted with a plurality of pixels all holding color information corresponding to at least one common color component, comprising: a similarity factor calculation step in which similarity factors are calculated for each pixel in the first image to determine an extent of similarity change, wherein each similarity factor is a sum of at least absolute differences between color information corresponding to different color components of said each pixel and its horizontally adjacent neighbors, or of said each pixel and its vertically adjacent neighbors; a color difference information generation step in which color difference information is generated by using color information in the first image, based upon the similarity factors having been calculated; a temporary color difference information correction step in which the generated color difference information is corrected; a color gradient analysis step in which a color gradient indicating an extent of color change is determined based upon the color difference information having been corrected; and an image conversion step in which the first image is converted to the second image based upon the color gradient having been determined.