Nonseparable Filters for Images in the Block DCT Domain
Jayanta Mukhopadhyay, Karthik Sairam · 2018
Filtering of images is required in various applications of image processing. Previously a few algorithms have been reported for filtering of images in the block discrete cosine transform (DCT) domain given its 2D finite impulse response (FIR). However, they assume that the response should be separable along rows and columns. In this paper, we propose a novel technique for implementing a non-separable 2D FIR filter in the block DCT domain. In this approach, we decompose a nonseparable 2D arbitrary FIR into a set of 2D separable arbitrary FIRs, and apply the computation of separable filters in the DCT domain. We have further used the sparsity of the DCT blocks and ranking of separable components in representing the nonseparable filter to reduce the computational cost allowing a graceful degradation of the quality of the filtered output.