Yalon Roterman and Moshe Porat,
Department of Electrical Engineering, 
Technion - Israel Institute of Technology 
Haifa 32000, Israel


Most color compression systems reduce the redundancies between the 
RGB color components by transforming the color primaries into a 
decorrelated color space, such as YIQ or YUV. In this paper a different 
compression approach is proposed. Since the high correlation of the 
RGB color channels implicitly suggests a localized functional relation 
between the components, it is used here in an alternative framework, 
by approximating subordinate colors as functions of a base color 
allowing that only a reduced number of parameters is required for 
coding the color information. Furthermore, since this correlation is 
particularly high locally, the image is first sub-divided into regions 
and for each region the correlation is analyzed and exploited separately. 
The size of the encoded regions is gradually reduced to allow 
progressively a more refined description of the transmitted image. 
Compression results of this progressive approach, which could be useful 
for slower communication channels, are presented and compared with 
JPEG as a typical example of the decorrelation approach. Our 
conclusion is that the proposed new approach to progressive image 
coding could be superior to presently available compression techniques.


Elsevier Image and Vision Computing, Vol. 25, pp. 637-651 (2007). 

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