VLSI implementation and performance evaluation of adaptive filters for impulse noise removal

An efficient VLSI implementation of Adaptive Rank Order Filter (AROF) and Adaptive Median Filter (AMF) is proposed in this paper. Impulse noise is introduced in digital images during image acquisition and transmission. The noise reduction algorithms remove noise without degrading image information. Linear filters tend to blur an image; hence they are not commonly used. Non-linear filters provide more satisfactory results in comparison to linear filters. The proposed paper adapts the filter based on the level of noise intensity in the image. AMF provides better filtering properties than standard median filters for images corrupted with 60% noise density. AROF provides better filtering properties than it is possible with AMF for images corrupted with higher noise densities (>60%). The VLSI architecture for AROF and AMF implements pipelining with parallel processing in order to speed up the filtering process. The performance of the proposed algorithm is compared with Peak Signal to Noise Ratio (PSNR) and Image Enhancement Factor (IEF).