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2016

Graph-based Dequantization of Block-Compressed Piecewise Smooth Images

3 years 10 months ago
Graph-based Dequantization of Block-Compressed Piecewise Smooth Images
—Block-based image or video coding standards (e.g. JPEG) compress an image lossily by quantizing transform coefficients of non-overlapping pixel blocks. If the chosen quantization parameters (QP) are large, then hard decoding of a compressed image—using indexed quantization bin centers as reconstructed transform coefficients—can lead to unpleasant blocking artifacts. Leveraging on recent advances in graph signal processing (GSP), we propose a dequantization scheme specifically for piecewise smooth (PWS) images: images with sharp object boundaries and smooth interior surfaces. We first mathematically define a PWS image as a low-frequency signal with respect to an inter-pixel similarity graph with edges of weights 1 or 0. Using quantization bin boundaries as constraints, we then jointly optimize the desired graph-signal and the similarity graph in a unified framework. A generalization to consider generalized piecewise smooth (GPWS) images—where sharp object boundaries are r...
Wei Hu, Gene Cheung, Masato Kazui
Added 10 Apr 2016
Updated 10 Apr 2016
Type Journal
Year 2016
Where SPL
Authors Wei Hu, Gene Cheung, Masato Kazui
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