Comparative Analysis of Decimation-Free Directional Filter Bank with Directional Filter Bank: In Context of Image Enhancement

This paper presents a new directional analysis tool namely decimation-free directional filter bank, and its comparison with directional filter bank. Outputs of directional filter bank are maximally decimated (smaller in size) due to the presence of decimators. Multi-rate identities are used to push all these decimators to the right of filters. By doing so, frequency scrambling produced in directional filter bank due to non-diagonalization of overall downsampling matrix is removed. No interpolation prior to image enhancement is required in decimation-free directional filter bank, as it was mandatory step before enhancement in directional filter bank. Artifacts produced due to interpolation can be misleading in situation like medical images, and aerial images. These artifacts are avoided in decimation-free directional filter bank as it requires no interpolation. Artifacts produced due to aliasing and folding during downsampling were also avoided in decimation-free directional filter bank due to absence of decimators. Synthesis in decimation-free directional filter bank at any stage, can be achieved by just simply adding all the images, as it was not the case with directional filter bank.