Appearance

CAIVANO, JOSE LUIS; GREEN-ARMYTAGE, PAUL

Encyclopedia of Color Science and Technology, 2nd ed.

Springer

Lugar: Berlin; Año: 2022; p. 1 - 9

Visual appearance refers to how things look toobservers. Objects have physical properties, andin this regard, optical properties are usually mostrelevant together with size, texture, shape, etc. Butwhat finally matters for vision is the appearancethat objects have for an observer (humanobservers will be mainly referred to in this article;however, this is not restrictive to human beingssince there are many other living species that havesimilar visual processing systems). The AmericanSociety for Testing and Materials (ASTM) as wellas the International Commission on Illumination(CIE) define appearance as the aspect of visualexperience by which objects are recognized [1, 2].The ASTM specifies, furthermore, the definitionof appearance from a psychophysical point ofview: “perception in which the spectral and geometricaspects of a visual stimulus are integratedwith its illuminating and viewing environment.”The physical properties have, of course, influenceon the way things look, but also the neurophysiologyand psychology of vision play a very importantrole in determining how objects and the worldappear to humans. Thus, it is important to understandvisual appearance not merely in regard tophysical aspects but as a sensation produced bythe visual system when processing stimulichanneled by means of light – visible radiation.Visual appearance, understood as a visual sensation,i.e., what humans see, has certain attributes,which are also visual sensations. These includecolor, visual texture, gloss, and transparency. Inthe ASTM definition the “spectral aspects” refer,of course, to color, and the remaining aspects(including the perceived shape, size, etc. ofobjects) are usually considered as “geometricaspects.” From these visual sensations observersget information about the environment and buildtheir knowledge of the external world, whichallows them to interact with the environment andwith other individuals.