Loss of gray-scale image information caused by swallowing is a common image processing and a bad solution. An improved histogram equalization method, to some extent, is introduced to avoid graphical information phagocytosis. The method uses rough set theory and approximate measure of the importance and classification of similar concepts, divided into a collection of appropriate boundaries, and compared to experiment. The results show that the improved histogram equalization histogram processed image clarity, detail-rich, graphical information can swallow to avoid phagocytosis.