Towards JPEG AIC part 3: visual quality assessment of high to visually lossless image coding

Due to the increasing number of pictures captured and stored every day by and on digital devices, lossy image compression has become inevitable to limit the needed storage requirement. As a consequence, these compression methods might introduce some visual artifacts, whose visibility depends on the chosen bitrate. Modern appli- cations target images with high to near-visually lossless quality, in order to maximize the visual quality while still reducing storage space consumption. In this context, subjective and objective image quality assessment are essential tools in order to develop compression methods able to generate images with high visual quality. While a large variety of subjective quality assessment protocols have been standardized in the past, they have been found to be imprecise in the quality interval from high to near-visually lossless. Similarly, an objective quality metric designed to work specifically in the mentioned range has not been designed yet. As current quality assessment methodologies have proven to be unreliable, a renewed activity on the Assessment of Image Coding, also referred to as JPEG AIC, was recently launched by the JPEG Committee. The goal of this activity is to extend previous standardization efforts, i.e. AIC Part 1 and AIC Part 2 (also know as AIC-1 and AIC-2), by developing a new standard, known as AIC Part 3 (or AIC-3). Notably, the goal of the activity is to standardize both subjective and objective visual quality assessment methods, specifically targeting images with quality in the range from high to near-visually lossless. Two Draft Calls for Contributions on Subjective Image Quality Assessment1, 2 were released, aiming at collecting contributions on new methods and best practices for subjective image quality assessment in the target quality range, while a Call for Proposals on Objective Image Quality Assessment is expected to be released at a later date. This paper aims at summarizing past JPEG AIC efforts and reviewing the main objectives of the future activities, outlining the scope of the activity, the main use cases and requirements, and call for contributions. Finally, conclusions on the activity are drawn.