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

scattering In physics, scattering is 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 particles and radiat ...

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.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 Reflection (physics), 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 witho ...

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

mirror A mirror, also known as a looking glass, is an object that Reflection (physics), reflects an image. Light that bounces off a mirror forms an image of whatever is in front of it, which is then focused through the lens of the eye or a camera ...

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 ...

phenomena are: gloss, haze, and orange peel. Various categories of visual appearance related to the perception of regular or diffuse reflection and transmission of light have been organized under the concept of cesia in an order system with three variables. In this system, DOI is connected to the variable called ''diffusivity''.

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