Abstract: In order to improve the enhancement effect of partial brighter and darker image, an improved gray image enhancement method is proposed, which is based on histogram equalization and single-scale retinex(SSR) algorithm. Improved histogram equalization enhancement for original image is carried out, the low frequency components of the original image were enhanced by histogram equalization, With the high frequency components fusion;SSR algorithm enhancement is carried out to original image. Weighted fusion of the two images is carried out. Results show that the image obtained by the new method is more prominent to highlight the details of the original image, and the visual effect is improved significantly. Contrast and entropy are enhanced, and the brightness is adjusted. The feasibility on medical X - ray images is verified. Compared with other enhancement algorithms, the new method is more conducive to the accurate analysis of images.

Key words: image processing; image enhancement; histogram equalization; SSR algorithm; image fusion