This investigation is a preliminary attempt to derive a figure-of-merit (FOM) characterizing the image degradation that can occur as a result of image compression. The usefulness of a visible difference predictor (VDP), which is based on previously published psychophysical models, is assessed. Specifically, this is a preliminary attempt to relate physical differences between an original image and a compressed version of the original to visible differences and then to calculate a FOM indicating the degree to which images have been degraded based on this visible difference. The FOM was applied to phantom images and to CT images that had been compressed at various ratios using either the JPEG algorithm or a wavelet compression algorithm. Comparisons between the VDP based measures and more traditional measures of image degradation suggest that, while this FOM may overcome some of the shortcomings of simpler measures such as root-mean-square (RMSE), the use of a VDP has limitations of its own.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.