Subtractive impairment, additive impairment and image visual quality

In this paper, we propose an engineering-based image quality metric which distinguishes subtractive impairment from additive impairment. Since the amount of subtractive impairment is up-bounded by the total details within the reference image but the same limitation can´t be applied to additive impairment, intuitively visual quality degradation due to the two types of impairments should be measured differently. In the proposed metric, subtractive and additive impairments are separated and represented in the wavelet domain, and their influences to image visual quality is measured by different equations. We tested the proposed metric on five subjectively-rated databases and proved its effectiveness in objective image quality assessment.