Blind Quality Assessment of PFA-Affected Images Based on Chromatic Eigenvalue Ratio

Abstract

Quality assessment of Purple Fringing Aberrated (PFA) images remains an unsolved problem because the original untainted natural image of the scene is not available at the point of analysis. As a result, the problem assumes the form of a blind assessment. This PFA is a false coloration localized around the edge regions where the contrast differential is high. One can, therefore, surmise that if this coloration is largely homogeneous in the chrominance space, the edge is expected to be crisp and the image sharp and clear. However, if this coloration pattern is diverse in the chrominance space, the edges will be fuzzy and this, in turn, will have an impact on the visual clarity of the image. The fringe diversity, therefore, becomes a measure of PFA image quality, provided the fringes are distributed in several parts of the image. This diversity has been captured by first characterizing the chrominance space spanned by the PFA pixels and then using the eigenvalue ratio as a measure of color diversity.