D. Image and Video Quality Assessment Perceptual objective image quality assessment uses an algorithm that evaluates the quality of pictures or video as a human observer would do based on the properties of the human visual system. Visual attention is one of the features that can be considered based on the rationale that an artifact is likely more annoying in a salient region than in other areas [62]. Most of objective quality assessment methods can be decomposed in two steps. Image distortion is first locally (pixel-based, block-based, etc.) evaluated resulting in a distortion map. In the second step, a pooling function is used to combine the distortion map values into a single quality score value. An intuitive idea to improve quality assessment methods using visual attention information is to give greater weight at the pooling stage to degradation appearing in salient areas than in nonsalient areas [63], [64]. Initial approaches consisted in weighting the distortion map using local saliency values before computing a linear or nonlinear mean. More recent studies, based on eye-tracking data, demonstrated that this simple weighting is not very effective [65], [66] in the case of compression artifacts. Nevertheless, such approaches can lead to significantly improved performance in the case of nonuniformly located distortions such as those due to transmission impairments [67]. Alternative weighting methods have been introduced for compression artifacts with varying success [68], [69]. In [70], more complex combinations of saliency map and distortion are introduced, assuming that weights should be a function of both saliency value and distortion level. You et al. [71], [72] revisit the problem at the distortion level for video content. Distortion visibility can be balanced according to the human contrast sensitivity function. As the latter is spatially nonuniform, gaze estimation should be considered to properly apply it.