Distinctness of image (DOI) is a quantification of the deviation of the direction of light propagation from the regular direction by

scattering Scattering is a term used in physics to describe a wide range of physical processes where moving particles or radiation of some form, such as light or sound, are forced to deviate from a straight trajectory by localized non-uniformities (including ...

during transmission or reflection. DOI is sensitive to even subtle scattering effects; the more light is being scattered out of the regular direction the more the initially sharp (well defined) image is blurred (that is, small details are lost). In polluted air it is the sum of all particles of various dimensions (dust, aerosols, vapor, etc.) that induces

haze Haze is traditionally an atmospheric phenomenon in which dust, smoke, and other dry particulates suspended in air obscure visibility and the clarity of the sky. The World Meteorological Organization manual of codes includes a classification ...

.Fan, Charles H. "Validation of Orange Peel Measurement of Paint Appearance on Composite Substrates" General Motors Corporation DOI is measured to characterize the

visual appearance The visual appearance of objects is given by the way in which they reflect and transmit light. The color of objects is determined by the parts of the spectrum of (incident white) light that are reflected or transmitted without being absorbed. Ad ...

of polished high- gloss surfaces such as automotive car finishes,

mirror A mirror or looking glass is an object that Reflection (physics), reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the ...

s, beyond the capabilities of gloss. Other

appearance Appearance may refer to: * Visual appearance, the way in which objects reflect and transmit light * Human physical appearance, what someone looks like * ''Appearances'' (film), a 1921 film directed by Donald Crisp * Appearance (philosophy), or p ...

phenomena are: gloss,

, and

orange peel An orange is a fruit of various citrus species in the family Rutaceae (see list of plants known as orange); it primarily refers to ''Citrus'' × ''sinensis'', which is also called sweet orange, to distinguish it from the related ''Citrus × ...

Reflected Image Quality (RIQ) vs. DOI

DOI is not sensitive to low amounts of orange peel on highest quality surfaces. RIQ has more proportionate response to orange peel on a wider range of surface finishes. RIQ works well in differentiating low gloss surfaces with different specular/diffuse components.

Parameters that affect RIQ

* Substrate alignment (horizontal/vertical) * Coating formulation * Substrate * Application technique

References

{{reflist * ''ASTM Standards on Color & Appearance Measurement'' * Richard S. Hunter, ''The Measurement of Appearance'', John Wiley & Sons (1987)

External links

Measurement Theory
Vision Optics