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Presentation Information     2007-03-05 (15:15)   •  The seminar room at Vi2

Speaker Khalid Niazi
Title Improved Directional FIlter Bank and Its appplication in Image Enhancement
Abstract Directional Filter Bank(DFB) can be thought of as a bank of filters which decomposes the Fourier Transform of an Image into Wedge-shaped like pass-bands. In the spatial domain, these pass bands correspond to features (not edges) of an image in a particular direction. DFB was originally designed for compression purpose, but later on it was used in different image processing application like image enhancement, fingerprint recognition, texture analysis, etc,. DFB is generally implemented in binary tree-structured way, where each node (image) decomposes into two further child nodes (sub-bands). The directional information present in the parent node is divided into two directionally orthogonal sub-bands. The sum of pixels in both the sub-bands is equal in size to their parent node. So, in DFB, directional resolution is inversely related to spatial resolution, and due to the presence of decimators, it cannot be kept under the category of TI systems. One main drawback of the DFB was the fact that due to non-diagonalization of overall downsampling matrix, all the outputs after the second stage were visually distorted. Later on this drawback was removed by the use of a Visualization matrix. We propose improved directional filter bank which can be used as an LTI System. The major feature of the proposed system is the fact that it doesn’t require any visualization matrix at any stage and directional resolution is made independent of spatial resolution. It requires no interpolation during the enhancement process as it was mandatory step in the previously proposed DFB.