“…This sub-task intends to make use of the distortion category information which is available in the legacy IQA datasets with some common synthetic distortions [11,161,162]. However, the massive Internet images captured by real cameras are usually afflicted by complex mixtures of multiple authentic distortions [7,163], which cannot be well-simulated by the limited algorithm-generated distortions in these legacy IQA datasets. As a result, such a distortion identification sub-task cannot accurately identify the complex mixtures of distortions existing in authentically distorted images and may lead to performance degradation when applying to evaluate the real-world images with diverse authentic distortions.…”