Histogram based image enhancement for non-uniformly illuminated and low contrast images

Non-uniform illumination and low contrast are commonly encountered in low light level night vision equipment and mammogram. This study presents a new method to enhance the non-uniformly illuminated and low contrast images. The proposed method first derives a bright enhancer and a dark enhancer based on the resultant image produced by a mean filter. By applying enhancer on the image, the dark region would be brighter and bright region would be darker. This will improves the non-uniformly illuminated image. Both qualitative and quantitative analyses show that the proposed method has successfully produced better performance in term of measure of enhancement as compare to three state-of-art methods namely Histogram Equalization, Contrast-Limited Adaptive Histogram Equalization and Adjust Image Intensity Values which available in Matlab Image Processing Toolbox.