IMAGE SEPARATION BASED ON NON SUBSAMPLED CONTOURLET (NSCT)

When an image or a document on a paper acquired through scanning, photographing or photocopying, the image on the back page may be show through. This cause a non-linear image mixture and should be resolved through a non-linear source separation. In this paper, we improve a previously introduced method, which suppose two independent images in the same point don't have same frequency. In this work we first give a mathematical analysis for an approximate linear separation as preprocessing; then nonlinear separation procedure is improved using Non-Subsampled Contourlet Transform (NSCT) instead of normal separable wavelet transform. The NSCT provides multiscale decomposition with directional filters at each scale. Furthermore, NSCT is very efficient in saving the geometric information of images and therefore it has very good feature localization. Experimental results show that our linear preprocessing and NSCT-based non-linear separation methods both have better separation quality, comparing with previously introduce methods.