Nonlinear mapping of the objective image quality assessment results in the aspect of correlation with subjective scores using various functions
2012
scientific article
english
- image quality assessment
- mean opinion scores
- MOS
- Differential MOS
- DMOS
- non-linear mapping
EN An ideal objective image quality assessment method should be linearly correlated with subjective scores expressed as Mean Opinion Scores (MOS) or Differential MOS. Such scores are representative for the human perception of various types of image distortions and can be obtained from several image quality databases containing a number of images corrupted by various distortions and their MOS/DMOS values. Unfortunately, the relation between even the most recently proposed image quality assessment methods and subjective scores is nonlinear. In order to compensate this, the Video Quality Experts Group has recommended the use of the logistic function for the additional nonlinear mapping. Nevertheless, its parameters obtained for each database are different so some other functions, e.g. simple polynomials, can also be applied for this purpose. The analysis of the results obtained for currently available image databases is presented in the last part of the paper.
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