Towads Objective Image Quality Metrics: The AIC Eval Program ofthe JPEG

摘要

Objective quality assessment of lossy image compression codecs is an important part of the recent call of the JPEG forAdvanced Image Coding. The target of the AIC ad-hoc group is twofold: First, to receive state-of-the-art still imagecodecs and to propose suitable technology for standardization; and second, to study objective image quality metrics toevaluate the performance of such codes. Even tthough the performance of an objective metric is defined by how well itpredicts the outcome of a subjective assessment, one can also study the usefulness of a metric in a non-traditional wayindirectly, namely by measuring the subjective quality improvement of a codec that has been optimized for a specificobjective metric. This approach shall be demonstrated here on the recently proposed HDPhoto format~(14)introduced byMicrosoft and a SSIM-tuned~(17)version of it by one the authors. We compare these two implementations with JPEG~1intwo variations and a visual and PSNR optimal JPEG2000~(13)implementation. To this end, we use subjective and objectivetests based on the multiscale SSIM and a new DCT based metric.