An Efficient VLSI Design of Threshold Filter using Removal of Impulse Noise using Wallace Tree Encoder

Abstract

Impulse noise often corrupts the images in the procedures of image acquisition and transmission. Denoising of image corrupted by impulse noise is a prominent research area in Image Processing. To carry out noise suppression many denoising schemes introduced which uses standard median filter or its modifications. However, these approaches might blur the image since both noisy and noise-free pixels are modified. An studied denoising scheme called threshold filter and its VLSI architecture introduced to avoid the damage on noise-free pixels and also for the removal of high density impulse noise. Decision Tree Based Denoising method is performed as two phase process — a detection phase and a filtering phase. Noisy pixels will be detected by decision-tree-based impulse noise detector followed by a direction oriented edge-preserving median filter. Based on the probability distribution function of noise and SNR information obtained from the image, the filter uses selection of filtering window of size 3X3 to perform de-noising. The filtering technique has been implemented on MRI images. The efficiency of the proposed filtering technique is verified with a study of the PSNR characteristic of the de-noised and noisy image with respect to the true image. The proposed de-noising technique shows an improvement in the contrast ratio and PSNR of the noisy image.