Integer Discrete Cosine Transform via Lossless Walsh-Hadamard Transform with Structural Regularity for Low-Bit-Word-Length

Taizo SUZUKI  Masaaki IKEHARA  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E93-A    No.4    pp.734-741
Publication Date: 2010/04/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E93.A.734
Print ISSN: 0916-8508
Type of Manuscript: PAPER
Category: Digital Signal Processing
integer discrete cosine transform (IntDCT),  dyadic values,  low-bit-word-length,  lossless Walsh-Hadamard transform (LWHT),  lossless-to-lossy image coding,  

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This paper presents an integer discrete cosine transform (IntDCT) with only dyadic values such as k/2n (k, n∈ in N). Although some conventional IntDCTs have been proposed, they are not suitable for lossless-to-lossy image coding in low-bit-word-length (coefficients) due to the degradation of the frequency decomposition performance in the system. First, the proposed M-channel lossless Walsh-Hadamard transform (LWHT) can be constructed by only (log2M)-bit-word-length and has structural regularity. Then, our 8-channel IntDCT via LWHT keeps good coding performance even if low-bit-word-length is used because LWHT, which is main part of IntDCT, can be implemented by only 3-bit-word-length. Finally, the validity of our method is proved by showing the results of lossless-to-lossy image coding in low-bit-word-length.