Perceptual contributions of blocky, blurry, and fuzzy impairments to overall annoyance

In this work, we used two types of impairments in a psychophysical experiment to measure the overall annoyance and individual strength of three impairment features (fuzzy, blocky, and blurry). The impairments were generated by compressing the original videos with MPEG-2 at two different bitrates: 1.0 and 7.5 Mbps. The heavily compressed videos presented blurry and blocky impairments, while the lightly compressed videos presented ‘fuzzy’ impairments, using a word provided by our test subjects. These impairments were then linearly combined in different proportions and strengths, generating videos in which all three impairment features are present. Our goal was to determine how these impairment features combine to produce the overall annoyance. A modified Minkowski metric was used to describe the ‘combination rule’ which relates the strengths of the impairment features to the overall annoyance. For the data set containing all test sequences, the optimal value found for the Minkowski parameter p was 1.55. From the data obtained, we also estimated the psychometric and annoyance functions. We found that for blocky-blurry and fuzzy artifacts there is no consistent difference between either the thresholds or mid-annoyance strengths.