Contrast enhancement is a very important issue in processing and analysing image, is a fundamental step in analyzation and segmentation image. These are mainly two categories: (1) indirect method of contrast enhancement and (2) direct method of contrast enhancement. a) About indirect method There are many indirect techniques, which were proposed in references. They only modifies the histogram, without using any contrast measure. In recent years, many researchers have applied fuzzy set theory to develope new techniques to enhance the contrast of the image. Fuzzy approach algorithms often lead to the requirement of designing a gray-scale transformation S-shape function (The function is continuous monotonous increase, decreasing the input gray level when the input is below the threshold, and increasing the value gray level input when the input is above the threshold). However, the selection of functions in the fuzzy rule inference to produce the gray-scale transformation S-shape function is not easy. With the following simple fuzzy rule