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On Integer DCT For Image Compression
Thesis

On Integer DCT For Image Compression

Yang, Kang-Tien
Masters, 國立清華大學, 資訊工程學系
1995

Abstract

影像壓縮 離散餘弦
Integer matrices constructed from dyadic transform (DT) are investigated. The goal is to find an optimal integer matrix to approximate discrete cosine transform (DCT) by simple integer operations to reduce the computations for image transform coding whereas keep the visual quality of the decoded images. The dyadic transform constructed based on dyadic symmetry (DS) is further studied and is compared with the traditional integer transforms such as high correlation transform (HCT), low correlation transform (LCT), and integer cosine transform (ICT) for coding images like Lenna, Baboon, and Jet. DT, HCT, LCT, DCT, and ICT are also evaluated based on the transform coding gain when the 1-st order Markov process is applied. Our experiments show that DT does perform faster than the fast DCT. However, the serious blocking effect can not be avoided when the high compression ratio is requested. A fast DT with high compression ratio and tolerant blocking effect merits further study.

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