Distinctness of image
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Visual appearance
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 light that are reflected or transmitted without being absorbed...
Distinctness of image, DOI, is a quantification of the deviation of the direction of light propagation from the regular direction by scattering
Scattering
Scattering is a general physical process where some forms of radiation, such as light, sound, or moving particles, are forced to deviate from a straight trajectory by one or more localized non-uniformities in the medium through which they pass. In conventional use, this also includes deviation of...
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 image details are being lost). In polluted air it is the sum of all particles of various dimensions (dust, aerosols, vapor, etc.) that induces haze
Haze
Haze is traditionally an atmospheric phenomenon where dust, smoke and other dry particles obscure the clarity of the sky. The World Meteorological Organization manual of codes includes a classification of horizontal obscuration into categories of fog, ice fog, steam fog, mist, haze, smoke, volcanic...
.
DOI is measured to characterize the visual appearance
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 light that are reflected or transmitted without being absorbed...
of polished high-gloss
Gloss (material appearance)
Gloss is an optical property, which is based on the interaction of light with physical characteristics of a surface. It is actually the ability of a surface to reflect light into the specular direction. The factors that affect gloss are the refractive index of the material, the angle of incident...
surfaces such as automotive car finishes, mirror
Mirror
A mirror is an object that reflects light or sound in a way that preserves much of its original quality prior to its contact with the mirror. Some mirrors also filter out some wavelengths, while preserving other wavelengths in the reflection...
s, beyond the capabilities of gloss.
| Distinctness of Image and Blur | |
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The blur induced by a scattering layer (here: frosted glass Frosted glass Frosted glass is produced by the sandblasting or acid etching of clear sheet glass. It has the effect of rendering the glass translucent by scattering of light during transmission, thus blurring images while still transmitting light.Applications:... ) increases with the distance between the information (ruler scaling) and the scattering layer. The scattering layer is close to the ruler surface on the left side and the distance increases to the right as does the blur. The distinctness of image decreases with increasing blur. |
Other appearance
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 light that are reflected or transmitted without being absorbed...
phenomena are: gloss
Gloss (material appearance)
Gloss is an optical property, which is based on the interaction of light with physical characteristics of a surface. It is actually the ability of a surface to reflect light into the specular direction. The factors that affect gloss are the refractive index of the material, the angle of incident...
, haze
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 light that are reflected or transmitted without being absorbed...
, and orange peel