A Fast DCT-SQ Scheme for Images

Yukihiro ARAI  Takeshi AGUI  Masayuki NAKAJIMA  

IEICE TRANSACTIONS (1976-1990)      No.11    pp.1095-1097
Publication Date: 1988/11/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: LETTER
Category: Image Processing, Computer Graphics and Pattern Recognition

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The sequence of 8-point DCT and scalar quantization is effective in image data compression. The operation is executed very efficiently, if the DCT coefficients need not to be found explicitly. The present paper proposes a method, requiring only five times of multiplication for the transform. The 8-point DCT can be comopsed from the 16-point DFT which gives only the real parts of coefficients, and final scaling. The real part DFT can be implemented by the small FFT Winograd algorithm, which requires only five multiplications. The final scaling can be combined with the quantizing matrix without any change in arithmetic complexity of the qunatizer. Since each signal path in the proposed algorithm has one multiplication at most, the five multiplications can be executed in parallel. This will make the hardware implementation of the algorithm effective.