COLOR PICTURE CODING - ALGORITHM OPTIMIZATION AND TECHNICAL REALIZATION

Among the image coding algorithms implementable today, threshold based transform coding systems are of special interest since they offer very high data compression ratios. In the present paper, concept and technical realization of a hybrid threshold coding scheme are described which combines the high energy compaction capability of the used Discrete Cosine Transform (DCT) with predictive coding of the spectral DC-coefficients. Using entropy coding for the 'overhead' information as well as for the spectral AC-coefficient values, the average bit rate necessary to encode colour images in reduced to less than 0. 7 bit per pel (bpp). A thresholding scheme which is oriented towards the human visual perception mechanisms and supported by edge detection is introduced and a new classification concept is discussed. The contribution is concluded by a discussion of the technical realization aspects.