Psychovisually tuned attribute operators for pre-processing digital video

In video compression, image pre-processing is used to improve the overall compression performance by removing noise from the image sequence. The compressibility can further be improved by removing other visually redundant information that the human visual system is not sensitive to, provided that the visual quality of the image sequence is preserved. A new approach to pre-processing is presented, based on attribute morphology in which extrema regions are removed provided that they meet some perceptual criterion, given by the attribute limit. Both the standard area and a new attribute, based on the power within the removed component, are investigated. Psychovisual experiments are used to determine the psychovisually lossless attribute limits and the limits expressed in a generalised form. The performance gain achieved by this approach is determined by comparing the codec outputs for original and the pre-processed images. Results show the compressibility of the pre-processed images, assessed by a number of compression methods, is significantly improved, thus demonstrating the advantages of the attribute morphology methods, with the power attribute providing the greatest improvement