Picture quality measurement based on block visibility in discrete cosine transform coded video sequences

• Published in: Journal of electronic imaging 2001-04, Vol.10 (2), p.498-510
• Main Authors: Coudoux, Francois-Xavier, Georges Gazalet, Marc, Derviaux, Christian, Corlay, Patrick
• Format: Article
• Language: English
• ISSN: 1017-9909; 1560-229X
• DOI: 10.1117/1.1344184

In this paper, we present a perceptual measure that predicts the visibility of the well-known blocking effect in discrete cosine transform (DCT) coded image sequences. The main objective of this work is to use the results of the measure derived for adaptive video postprocessing, in order to significantly improve the visual quality of the video decoded sequences at the receiver. The proposed measure is based on a visual model accounting for both the spatial and temporal properties of the human visual system. The input of the visual model is the distorted sequence only. Psycho-visual experiments have been carried out to determine the eye sensitivity to blocking artifacts, by varying a number of visually significant parameters: background level, spatial, and temporal activities in the surrounding image. Results obtained for the measurement of the visibility thresholds enable us to estimate the model parameters. The visual model is finally applied to real coded video sequences. The comparison of measurement results with subjective tests shows that the proposed perceptual measure has a good correlation with subjective evaluation. ©