Brightness Preserving Image Contrast Enhancement using Spatially Weighted Histogram Equalization

This paper presents a simple and effective method for image contrast enhancement called spatially weighted histogram equalization. Spatially weighted histogram not only considers the times of each grey value appears in a certain image, but also takes the local characteristics of each pixel into account. In the homogeneous region of an image, the spatial weights of pixels tend to zero, whereas at the edges of the image, this weights are very large. In order to maintain the mean brightness of the original image, the grey level transformation function calculated by spatial weighted histogram equalization is modified, and the final result is given by mapping the original image through this modified grey level transformation function. The experimental results show that the proposed method has better performance than the existing methods, and preserve the original brightness quite well, so that it is possible to be utilized in consumer electronic products.