Multi Scale Decomposition and Edge Preserving Filter Based Satellite Image Resolution Enhancement - A Review

Resolution enhancement (RE) schemes which are not based on wavelets has one of the major drawbacks of losing high frequency contents which results in blurring. The discrete wavelettransform-based (DWT) Resolution Enhancement scheme generates artifacts (due to a DWT shift-variant property). A wavelet-Domain approach based on dual-tree complex wavelet transform (DT-CWT) & nonlocal means (NLM) is proposed for RE of the satellite images. A satellite input image is decomposed by DT-CWT (which is nearly shift invariant) to obtain high-frequency sub bands. Here the Lanczos interpolator is used to interpolate the high-frequency sub bands & the low-resolution (LR) input image. The high frequency sub bands are passed through an NLM filter to cater for the artifacts generated by DT-CWT (despite of its nearly shift invariance). The filtered high-frequency sub bands and the LR input image are combined by using inverse DTCWT to obtain a resolution-enhanced image. Objective and subjective analyses show superiority of the new proposed technique over the conventional and state-of-the-art RE techniques.