Single-Ended Instrumental Models of Image Quality

Abstract

In the previous chapter, we have studied double-ended instrumental measures for image quality. The two most common characteristics of existing double-ended measures are that they apply image filtering that is inspired by known perceptual mechanisms in the visual system, and that they integrate the differences between the filtered original and processed or coded image to arrive at a distortion measure. In this integration step, all differences between the filtered images are treated as being equivalent. In this chapter, an alternative perspective on image quality modelling is proposed that is in better agreement with the experimental approach towards measuring image quality that was discussed in chapter 5. This more cognitively-based perspective is inspired by two observations, i.e.,

• 1 that people are able to analyze and justify their image quality judgements, and

• 2 that people are able to make such judgements in the absence of an “original” (or undistorted) image.