DCT Coefficient Block Size Classification for Image Coding

KIPS Transactions on Computer and Communication Systems, Vol. 4, No. 3, pp. 880-894, Mar. 1997
10.3745/KIPSTE.1997.4.3.880,   PDF Download:


In this paper, we propose a new algorithm to perform DCT(Discrete Cosine Transform) within the area reduced by predicting position of quantization coefficients to be zero. This proposed algorithm not only decreases the encoding time and the decoding time by reducing computation amount of FDCT(Forward DCT) and IDCT(Inverse DCT) but also increases compression ratio by performing each different horizontal-vertical zig-zag scan according to the classified block size for each block on the huffman coding. Traditional image coding method performs the same DCT computation and zig-zag scan over all blocks, however this proposed algorithm reduces FDCT computation time by setting to zero instead of computing DCT for quantization coefficients outside classified block size on the encoding. Also, the algorithm reduces IDCT computation time by performing IDCT for only dequantization coefficients within classified block size on the decoding. In addition, the algorithm reduces Run-Length by carrying out horizontal-vertical zig-zag scan appropriate to the classified block characteristics, thus providing the improvement of the compression ratio. On the other hand, this proposed algorithm can be applied to 16*16 block processing in which the compression ratio and the image resolution are optimal but encoding time and the decoding time take long. Also, the algorithm can be extended to motion image coding requiring real time processing.

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Cite this article
[IEEE Style]
K. K. In, K. J. Il, J. K. Won, L. K. Bae and K. H. Ug, "DCT Coefficient Block Size Classification for Image Coding," KIPS Journal (1994 ~ 2000), vol. 4, no. 3, pp. 880-894, 1997. DOI: 10.3745/KIPSTE.1997.4.3.880.

[ACM Style]
Kang Kyeong In, Kim Jeong Il, Jeong Keun Won, Lee Kwang Bae, and Kim Hyen Ug. 1997. DCT Coefficient Block Size Classification for Image Coding. KIPS Journal (1994 ~ 2000), 4, 3, (1997), 880-894. DOI: 10.3745/KIPSTE.1997.4.3.880.