Title :
Zerotree coding of DCT coefficients
Author :
Monro, D.M. ; Dickson, G.J.
Author_Institution :
Sch. of Electron. & Electr. Eng., Bath Univ., UK
Abstract :
We show that an efficient quantizer originally developed for wavelet compression can be applied to DCT coding with excellent results. We have implemented a system for block-based, embedded, progressive, DCT image compression which makes use of the embedded zerotree wavelet (EZW) algorithm of Shapiro (1993). The image is partitioned into a number of distinct square blocks and the DCT applied to each of these individually. The coefficients are then rearranged into a sub-band structure which outwardly resembles a wavelet transformed image, with the number of sub-bands being related to the size of the DCT used. The zerotree coding algorithm is then employed to quantize the coefficients. The system outperforms the embedded zerotree wavelet scheme in a rate-distortion sense, with good performance from lossless (to the fixed point DCT precision) to high compression. The system gives the best trade between accuracy and high frequency ringing with a DCT block size of 16×16, corresponding to four sub-band scales
Keywords :
data compression; discrete cosine transforms; image coding; image segmentation; quantisation (signal); rate distortion theory; transform coding; wavelet transforms; DCT coding; DCT coefficients; accuracy; block size; block-based image compression; embedded zerotree wavelet algorithm; fixed point DCT precision; high frequency ringing; image compression; lossless compression; performance; progressive image compression; quantizer; rate-distortion; sub-band structure; wavelet compression; wavelet transformed image; zerotree coding; Decorrelation; Discrete cosine transforms; Discrete wavelet transforms; Electronic mail; Frequency; Image coding; Internet; Partitioning algorithms; Performance loss; Quantization; Rate-distortion;
Conference_Titel :
Image Processing, 1997. Proceedings., International Conference on
Conference_Location :
Santa Barbara, CA
Print_ISBN :
0-8186-8183-7
DOI :
10.1109/ICIP.1997.638849