Color Moving Pictures Quality Metric (CMPQM)

CMPQM is an extension of the MPQM metric to consider the effect of color on the quality. The first step in the computation of the metric is to transform the uncorrected color components into RGB values that are linear with luminance. The second step converts the linear RGB values into coordinate values in the chosen opponent-colors space. The three coordinates of this color-opponent space correspond to luminance (B/W), red-green (R/G), and blue-yellow (B/Y) channels. Then, each color component of the original and error images (B/W, R/G, and B/Y) is analyzed by a filter bank created by Gabor functions tuned in spatial frequency and orientation. The bank uses the same filters as the MPQM, except in numbers. The B/W pathway is processed as the luminance data are processed by MPQM, i.e. it is decomposed into 34 components by the seventeen spatial and two temporal filters. It is known that the R/G and B/Y pathways are much less sensitive than the B/W one. Therefore, a restricted number of filters is used for such pathways. Nine spatial filters are used with a single temporal low-pass filter. The remaining of the computation is as in the MPQM. Contrast thresholds are computed and the data is pooled over the channel to yield a distortion measure.