Visual appearance: Difference between revisions

Revision as of 18:42, 14 July 2015

Revision as of 19:19, 12 August 2015

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== Appearance of reflective objects ==

The appearance of reflecting objects is determined by the way the surface reflects incident [[light]]. The reflective properties of the surface can be characterized by a closer look at the (micro)-[[topography]] of that surface.

Structures on the surface and the texture of the surface are determined by typical dimensions between some 10 mm and 0.1 mm (the detection limit of the human eye is at ~0.07 mm). Smaller structures and features of the surface cannot be directly detected by the unaided eye, but their effect becomes apparent in objects or images reflected in the surface. Structures at and below 0.1 mm reduce the ''[[Distinctness of image|distinctness of image]]'' (DOI), structures in the range of 0.01 mm induce ''[[Haze|haze]]'' and even smaller structures affect the ''[[Gloss (material appearance)|gloss]]'' of the surface.

::'''Definition<br />diffusion, [[scattering]]''': process by which the spatial distribution of a beam of radiation is changed in many directions when it is deviated by a surface or by a medium, without change of frequency of its monochromatic components.<ref>CIE No17.4-1987: International lighting vocabulary, 4th ed. (Joint publication IEC/CIE)</ref>

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== Terminology ==

'''Reflective objects''' <ref>ASTM Standards on Color & Appearance Measurement</ref>

* ''Reflectance factor, R''

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* ''Reflection haze, H'' (for a specified specular angle), the ratio of ([[light]]) [[flux]] reflected at a specified angle (or angles) from the [[specular]] direction to the flux similarly reflected at the specular angle by a specified gloss standard.<ref>ASTM E–430: Standard Test Methods for Measurement of Gloss of High-Gloss Surfaces by Goniophotometry</ref>

'''Transmissive objects''' <ref>ASTM Standards on Color & Appearance Measurement</ref>

* ''[[Transmittance]], T''