An efficient method for contrast enhancement of digital mammographic images

Abstract

Mammogram images are very sensitive and a little change in environment affect the quality of the images. It is difficult to analyze the minute changes in mammogram images due to lack of expert radiologists. If the contrast of the mammogram images can be changed manually or with pre-processing of image then it is easy to interpret the images. In this chapter a new method is proposed for contrast enhancement of digital mammogram images. Proposed method is based on wavelet based variable gain modified sigmoid function. In this method after wavelet subband decomposition of the image, variable gain modified sigmoid function is applied on the image. In the final step the result of previous step is processed by adaptive histogram equalization. The qualitative and subjective performance of proposed method is evaluated on MIAS database images. The performance of the proposed method is compared with existing methods in terms of EME, EMF and CPU time. Simulation results indicate that the proposed method provides better image qualitative and quality performance as compared to existing algorithms.