Under-sampled and over-sampled pre-/post-filters for block DCT coders (TA-L4)

Author(s) : Chengjie Tu (Windows Digital Media Division, Microsoft Corporation, USA) Trac D. Tran (ECE Department, The Johns Hopkins University, USA) Jie Liang (School of Engineering Science, Simon Fraser University, Canada)

Abstract : Pre-/post-filtering operators have been shown to improve the coding efficiency as well as to mitigate blocking artifacts in traditional DCT-based block coders. Pre-/post-filters which preserve the system sampling rate have been extensively investigated. This paper explores the two non-critically-sampled signal decomposition cases - under-sampling and over-sampling - via the pre-/post-processing perspective. We discuss various design issues, efficient structures, and present two application examples: under-sampled pre-/post-filters for very low bit-rate image coding and over-sampled pre-/post-filters for error resilient image transmission. Preliminary experimental results illustrate that non-critically-sampled pre-/post-filtering does provide much improved coding performances than its critically-sampled counterpart for the aforementioned specific applications.

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