Mahmoud R. El-Sakka and Mohamed S. Kamel, "A Segmentation 
                  Criterion for Digital Image Compression", IEEE International 
                  Conference on Acoustics, Speech and Signal Processing, 
                  ICASSP'1995, pp. 2551-2554, May 1995, Detroit, Michigan, USA.
               
               
               
               Abstract
               
               
               
                  This paper is concerned with segmenting light intensity 
                  images for the sake of compressing them using lossy 
                  compression techniques. Among the most commonly used 
                  techniques for image segmentation is Quad-tree partitioning. 
                  In this technique, block variance based criteria are usually 
                  used to measure the smoothness of the segmented blocks and to
                  consequently classify them.  Block variance, however, does 
                  not consider the pixel value distribution within the block. 
                  Instead of using the block variance as a segmentation and 
                  classification measure, we propose using the mean squared 
                  deviation from the neighboring pixels mean.  The proposed 
                  measure is capable of differentiating between blocks not only
                  according to block pixel values  but also according to their
                  distribution within the block.  This leads to a much better
                  image segmentation and consequently to higher image 
                  compression ratios with lower image degradation. The results 
                  show the superiority of the proposed measure over the ! 
                  block variance measure.