| 摘要 |
PROBLEM TO BE SOLVED: To hold a dynamic range of gradation on a color of a pixel included in a region of an inputted image without reducing it as much as possible and to reduce the number of colors.SOLUTION: A dynamic range on gradation of individual color components in a color space is obtained on a pixel included in a region of an inputted image, and the dynamic ranges of the individual color components are divided to divide a rectangular parallelepiped corresponding to the dynamic ranges of the individual color components into blocks of small rectangular parallelepipeds. Pre-processing for reducing the number of colors in the region of the image by replacing the gradation of the individual color components of the pixels included in the respective blocks with gradation of a nearest apex of the block is performed. The pre-processed pixels whose distance on a color space are near are collected into a set, and representative colors of the respective sets are determined. Thus, processing for reducing the number of colors in a region of the image is performed. |
