A texture image processing system for image processing apparatus comprises, first calculator for calculating a maximum value and a minimum value of texture image data; second calculator for calculating an average value and a gain value with employment of said maximum value and minimum value; and synthesizing processor for synthesizing texture image data by image picture data, this synthesizing processor synthesizing the texture image data with the image picture data by multiplying a difference between the texture image data and the average value by the gain value. Also, synthesizing processor synthesizes the texture image data with chromaticity information of the image picture data, or chromaticity information of the image picture data with predetermined chromaticity information, chromaticity information of the texture image data. With the above-described structures, both of hue and saturation in the image picture data are maintained, and also the synthesized texture image having no great brightness change over its entire region is obtained.