The perception of gloss: a review.

Gloss is a relatively little studied visual property of objects' surfaces. The earliest recorded scientific reference to gloss appears to have been by Ingersoll in 1921: studies at this time were based on the assumption that gloss could be understood as an inherent physical property of a surface, and the priority was to devise a satisfactory method and scale to measure it reliably. As awareness of the complexity of perception grew, efforts were made to distinguish different types of gloss, although these generally still took the form of a search for objective physical measures to be solved within the visual system by means of inverse optics. It became more widely recognised approximately 20 years ago that models of gloss perception based on inverse optics were intractable and failed to explain experimental findings adequately. A temporary decline in the number of published studies followed; however the last decade or so has seen a renewal of interest in the perception of gloss, in an effort to map what is now understood to be a complex interaction of variables including illumination, surface properties and observer. This appears to have been driven by a number of factors, as the study of gloss re-emerged from research into other surface properties such as colour and texture, with technological advances paving the way for new experimental techniques and measurements. This review describes the main strands of research, tracking the changes in approach and theory which have triggered new avenues of research, to the current state of knowledge.