Filtering using phase) One of the limitations of the noise-smoothing linear filters is that their frequency response has zero phase. This means the phase distortions due to noise remain unaffected by these algorithms. To see the effect of phase, enhance a noisy image (with, for instance, SNR = 3 dB) by spatial averaging and transform processing such that the phase of the enhanced image is the same as that of the original image (see Fig. P7.6). Display u (m, n), u (m, n) and u(m, n) and compare results at different noise levels. If, instead of preserving ll(k, l ), suppose we preserve 10% of the samples "1(m, n) ?[IDFf{exp j8(k, /)}] that have the largest magnitudes. Develop an algorithm for enhancing the noisy image now.
