Subjective video quality

Subjective video quality is video quality as experienced by humans. It is concerned with how video is perceived by a viewer (also called 'observer' or 'subject') and designates their opinion on a particular video sequence and therefore related to the field of Quality of Experience. The measurement of subjective video quality is necessary since objective quality assessment algorithms such as PSNR have been shown to correlate badly with ratings. Subjective ratings may also be used as ground truth to develop new algorithms. Subjective video quality is video quality as experienced by humans. It is concerned with how video is perceived by a viewer (also called 'observer' or 'subject') and designates their opinion on a particular video sequence and therefore related to the field of Quality of Experience. The measurement of subjective video quality is necessary since objective quality assessment algorithms such as PSNR have been shown to correlate badly with ratings. Subjective ratings may also be used as ground truth to develop new algorithms. Subjective video quality tests are psychophysical experiments in which a number of viewers rate a given set of stimuli. These tests are quite expensive in terms of time (preparation and running) and human resources and must therefore be carefully designed. In subjective video quality tests, typically, SRCs ('Sources', i.e. original video sequences) are treated with various conditions (HRCs for 'Hypothetical Reference Circuits') to generate PVSs ('Processed Video Sequences'). The main idea of measuring subjective video quality is similar to the Mean Opinion Score (MOS) evaluation for audio. To evaluate the subjective video quality of a video processing system, the following steps are typically taken: