A Novel Approach for the design of 2D Sharp Circularly Symmetric FIR Filters
In applications like weather monitoring, remote sensing, seismic signal processing etc, the boundaries and sharp features of the images have to be enhanced to obtain useful results and interpretations. The two dimensional(2D) highpass filters are used for such image processing applications. A direct design of the 2D high pass filter using frequency transformation has not been reported in the literature so far. In this paper, we present the design of a sharp 2D high pass filter using a direct transformation of the 1D low pass filter into a 2D high pass filter. Chebyshev polynomial approximation is used in mapping the one dimensional (1D)filter into its 2D equivalent. A promising aspect of the proposed transformation is that it is multiplier-free. Therefore the total complexity is decided by the multipliers of the 1D prototype filter. The complexity of designing a sharp 1D filter can be reduced by using the technique of Frequency Response Masking (FRM). Better circularity of the contour in the cutoff radius of the 2D filter is achieved compared to the traditional McClellan transformation. Reduced computation time and complexity are the highlights of the proposed approach.
