Enhancing colour image quality in television displays

Abstract

A general framework and first experimental results are presented for a computational model for achieving optimal colour appearance of natural images on television displays. The image quality framework includes: (a) analysis of relationships between overall image quality and quality-related attributes; (b) analysis of relationships between the quality-related attributes and their psychometric correlates; (c) analysis of relationships between the psychometric correlates and the physical parameters of a display; and (d) development of an adaptive algorithm for optimal image appearance by manipulation of the display’s parameters. In the psychophysical experiments, observers viewed a series of colour images on high-end consumer television display, to investigate the relationships between overall image quality and four quality-related attributes: brightness rendering, chromatic rendering, visibility of details and overall naturalness. The results of the experiments suggest that these attributes are interrelated. Some subjects can more easily separate the quality-related attributes than other subjects. The overall image quality can be modelled as a linear combination of the brightness rendering and chromatic rendering judgements with different weights, which are subject dependent. The optimal value of the overall image quality judgements is slightly skewed towards the darker end of the lightness scale and towards the more colourful end of the chroma scale. The degree of skewedness depends on image content.

Key Words:

• Colour image quality
• Television display
• Visual perception