Edge Preserving Lossy Image Compression with Wavelets and Contourlets

In this paper an edge preserving lossy image coder is presented. An edge image is obtained from the original with a digital image processing module using four different filters: Canny, Sobel, Roberts and Prewitt, then the original image is domain transformed with wavelets or contourlets, and a pixel mapping from original domain to transformed is done. For the compression, the edges points and the approximation image (which determines the compression factor) are selected; finally the image is decompressed in order to observe the reconstruction quality and edge preserving. The stages of the compression system are: a) Image selection, b) Digital image processing, c) Feature vector extraction, d) Domain Transformation, e) Pixel mapping, f) Image compression and g) Image decompression. Additionally, the results obtained from comparisons of error measures between original and decompressed images are shown and finally conclusions about the coder are presented.