ABSTRACT
This chapter reviews the quantification of image quality, as carried out by imaging scientists, designers and engineers, who are concerned with the design, implementation and manufacturing of imaging systems. It identifies the most useful objective imaging performance measures employed in their quantification. The chapter addresses qualitative methods such as image psychophysics and psychometric scaling. These methods are employed to quantify the quality of images, to derive thresholds of visibility of image defects or artefacts and just-noticeable differences between image stimuli. The quality criteria of the observer are based on various cognitive factors, such as memory, influences, experience, expectations and result in a variation of assessments among individuals as well as temporal variations for any one individual. Measurements relating to image quality assume that there is a functional relationship between the subjective impression of image quality and some selected attributes of the observed stimuli.
