A DISTORTION MEASURE FOR BLOCKING ARTIFACTS IN IMAGES BASED ON HUMAN VISUAL SENSITIVITY

A visual model that gives a distortion measure for blocking artifacts in images is presented. Given the original and reproduced image as inp uts, the model output is a numerical value that quantifies the visibil ity of blocking error in the reproduced image, The model is derived ba sed on the human visual sensitivity to horizontal and vertical edge ar tifacts that result from blocking, Psychovisual experiments have been carried out to measure the visual sensitivity to these artifacts, In t he experiments, typical edge artifacts are shown to subjects and the s ensitivity to them is measured with the variation of background lumina nce, background activity; edge length, and edge amplitude. Synthetic t est patterns are used as background images in the experiments, The sen sitivity measures thus obtained are used to estimate the model paramet ers, The final model is tested on real images, and the results show th at the error visibility predicted by the model correlates well with th e subjective ranking.