Fuzzy weighted histogram equalisation for contrast enhancement of mammogram images

Abstract

The early detection of breast cancer in the mammograms is very important in the field of medicine. Histogram equalisation is mainly used for contrast enhancement. The histogram equalisation (HE) usually results in excessive contrast enhancement because of lack of control on the level of enhancement. A novel technique, Fuzzy Weighted Histogram Equalisation (FWHE) for Contrast Enhancement of Mammogram Images is presented in this paper. The proposed method consists of three stages. First, the grey level intensities of the original mammogram image are transformed to fuzzy plane and the amount of fuzziness is adjusted by using contrast intensification operator. In the second stage, the Probability Distribution Function (PDF) of the fuzzy matrix is modified by applying weighting and thresholding and then, the HE procedure is applied to the fuzzy plane of the mammogram image. Finally, the fuzzy plane is de-fuzzified to get contrast enhanced mammogram image. From the qualitative and quantitative measures, it is interesting to see that the proposed method provides optimum results by giving better contrast enhancement and preserving the local information of the original mammogram image.