19 April 2000 Semi-optimized padding method for arbitrarily shaped image coding
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In this paper, we propose a new 'padding method,' which is a technique allowing encoding with a squared block by assigning imaginary values to pixels except in an object. We show our methods to be more effective in coding performance than conventional ones. We theoretically study padding method from the viewpoint of the coding performance, or rate-distortion. We first define the criteria function to evaluate each padding method, and then concretely propose how to determine padding pixel values. We select a criterion for distribution of coefficients after applying the DCT and for quantized error of DCT coefficients after quantization. Pixel values to be filled in background pixels can then also be calculated so that both entropy and quantized error are also low for determined quantizer. We tested our padding method by computer simulation using test squared blocks (8 X 8 pixels). Results of testing showed our proposed method performed on average 2 or 3 dB at the entire bit-rate compared to be the MPEG-4 VM padding method. We then adapted padding method to entire test images (having no segmentation information) and found that the coding performance increased about 0.5 or 0.6 dB compared to the method which applying a typical 2D-DCT.
© (2000) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Koh'ichi Takagi, Koh'ichi Takagi, Atsushi Koike, Atsushi Koike, Shuichi Matsumoto, Shuichi Matsumoto, } "Semi-optimized padding method for arbitrarily shaped image coding", Proc. SPIE 3974, Image and Video Communications and Processing 2000, (19 April 2000); doi: 10.1117/12.383002; https://doi.org/10.1117/12.383002


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