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Proceedings Paper

Adaptive postfiltering for reducing blocking and ringing artifacts in low-bit-rate coding
Author(s): Changick Kim
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Paper Abstract

In this paper, we present a method to reduce blocking and ringing artifacts in low bit-rate block-based video coding. For each block, its DC value and DC values of the surrounding eight neighbor blocks are exploited to predict low frequency AC coefficients. Those predicted AC coefficients allow to infer spatial characteristics of a block before quantization stage in the encoding system. They are used to classify each block into either of two categories, low-activity and high-activity block. In the following post-processing stage, two kinds of low pass filters are adaptively applied according to the classified result on each block. It allows for strong low pass filtering in low-activity regions where the blocking artifacts are most noticeable, whereas it allows for weak low pass filtering in high-activity regions to reduce ringing noise as well as blocking artifacts without introducing undesired blur. In the former case, the blocking artifacts are reduced by one dimensional (1-D) horizontal and vertical low pass filters, and selective use of horizontal/vertical direction is adopted depending on the absolute values of the predicted AC coefficients. In the latter case, deblocking and deringing is conducted by a single filter, which makes the architecture simple. TMN8 decoder for H.263+ is used to test the proposed method. The experimental results show that the proposed algorithm is efficient and effective in reducing ringing artifacts as well as blocking artifacts from the low bit-rate block-based video coding.

Paper Details

Date Published: 22 May 2002
PDF: 9 pages
Proc. SPIE 4667, Image Processing: Algorithms and Systems, (22 May 2002); doi: 10.1117/12.468014
Show Author Affiliations
Changick Kim, Epson Research and Development, Inc. (United States)


Published in SPIE Proceedings Vol. 4667:
Image Processing: Algorithms and Systems
Edward R. Dougherty; Jaakko T. Astola; Karen O. Egiazarian, Editor(s)

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