Title :
Lossless, near-lossless and lossy adaptive coding based on the lossless DCT
Author :
Chokchaitam, S. ; Iwahashi, Masahiro
Author_Institution :
Fac. of Eng., Nagaoka Univ. of Technol.
fDate :
6/24/1905 12:00:00 AM
Abstract :
This report proposes a new coding method, which realizes lossless, near-lossless and lossy coding with a unified single algorithm. The method is based on a lifting-structured lossless DCT, which maps an "integer" input vector to also an "integer" output vector. The proposed method can be used as not only a high performance "lossless" encoder but also a "lossy" encoder compatible with conventional DCT-based methods such as JPEG and MPEG. In addition, it has a "near-lossless" mode in which compression ratio is better than lossless mode retaining quite good quality of decoded images. In "lossless" mode, only the lossless DCT and an entropy coder are used. In "lossy" mode, transformed coefficients are quantized and then entropy coded in the same manner as the conventional method for compatibility. In "near-lossless" mode, signals are quantized before DCT to avoid SNR degradation due to "rounding" operations in the lossless DCT.
Keywords :
adaptive codes; code standards; data compression; discrete cosine transforms; entropy codes; image coding; quantisation (signal); transform coding; JPEG; MPEG; adaptive coding; compression ratio; digital image coding; discrete cosine transform; entropy coder; high performance encoder; image quality; integer input vector; integer output vector; lifting-structured lossless DCT; lossless coding; lossy coding; near-lossless coding; rounding operations; transformed coefficient quantization; unified single algorithm; Adaptive coding; Decoding; Degradation; Digital images; Discrete cosine transforms; Entropy; Image coding; Performance loss; Quantization; Transform coding;
Conference_Titel :
Circuits and Systems, 2002. ISCAS 2002. IEEE International Symposium on
Print_ISBN :
0-7803-7448-7
DOI :
10.1109/ISCAS.2002.1009957
