Exploring subjective image quality through isopreference curves

Perceptual image quality correlates ineffectively with the traditional error measures. By defining the factors behind perceived image quality, many image processing systems can be optimized. Thus, a great deal of effort has been made for solving this challenging issue. However, considerably less research has been focused on the role of spatial resolution and number of gray levels in subjective image quality. In our study, the relation between these two fundamental image parameters is experimentally defined in terms of perceptual quality. The study was carried out by organizing an experiment where 80 subjects were used. Using the collected data set, the results are illustrated in the form of isopreference curves. Finally, our results are compared with the corresponding ones presented previously. Although the comparison reveals a clear correlation between the results, novel information about the relation between spatial resolution and the number of gray levels is presented.