PERCEPTUAL QUALITY METRICS APPLIED TO STILL IMAGE COMPRESSION

We present a review of perceptual image quality metrics and their appl ication to still image compression. The review describes how image qua lity metrics can be used to guide an image compression scheme and outl ines the advantages, disadvantages and limitations of a number of qual ity metrics. We examine a broad range of metrics ranging from simple m athematical measures to those which incorporate full perceptual models . We highlight some variation in the models for luminance adaptation a nd the contrast sensitivity function and discuss what appears to be a lack of a general consensus regarding the models which best describe c ontrast masking and error summation. We identify how the various perce ptual components have been incorporated in quality metrics, and identi fy a number of psychophysical testing techniques that can be used to v alidate the metrics. We conclude by illustrating some of the issues di scussed throughout the paper with a simple demonstration. (C) 1998 Els evier Science B.V. All rights reserved.