Why Reducing Contrast Reduces Clarity
The ability of a person with normal visual acuity to see fine details is determined by his or her contrast sensitivity. Contrast sensitivity is the reciprocal of the smallest contrast for which a person can see a sine-wave grating. A person's contrast sensitivity function is contrast sensitivity as a function of spatial frequency. Normally, peak contrast sensitivity is at about 4 cycles per degree of visual angle. At higher spatial frequencies, comprising finer and finer lines, contrast sensitivity decreases, until at about 40 cycles per degree even the brightest of bright lines and the darkest of dark lines cannot be seen.
The high spatial frequencies in an image give it its fine details. Reducing the contrast of an image reduces the visibility of these high spatial frequencies because contrast sensitivity for them is already poor. This is how a reduction of contrast can reduce the clarity of an image—by removing its fine details.
It is important to emphasize that reducing the contrast is not the same as blurring an image. Blurring is accomplished by reducing the contrast only of the high spatial frequencies. Aerial perspective reduces the contrast of all spatial frequencies.
Read more about this topic: Aerial Perspective
Famous quotes containing the words reducing, contrast, reduces and/or clarity:
“[The Republicans] offer ... a detailed agenda for national renewal.... [On] reducing illegitimacy ... the state will use ... funds for programs to reduce out-of-wedlock pregnancies, to promote adoption, to establish and operate children’s group homes, to establish and operate residential group homes for unwed mothers, or for any purpose the state deems appropriate. None of the taxpayer funds may be used for abortion services or abortion counseling.”
—Newt Gingrich (b. 1943)
“By contrast with history, evolution is an unconscious process. Another, and perhaps a better way of putting it would be to say that evolution is a natural process, history a human one.... Insofar as we treat man as a part of nature—for instance in a biological survey of evolution—we are precisely not treating him as a historical being. As a historically developing being, he is set over against nature, both as a knower and as a doer.”
—Owen Barfield (b. 1898)
“A man is the prisoner of his power. A topical memory makes him an almanac; a talent for debate, disputant; skill to get money makes him a miser, that is, a beggar. Culture reduces these inflammations by invoking the aid of other powers against the dominant talent, and by appealing to the rank of powers. It watches success.”
—Ralph Waldo Emerson (1803–1882)
“In contrast to the flux and muddle of life, art is clarity and enduring presence. In the stream of life, few things are perceived clearly because few things stay put. Every mood or emotion is mixed or diluted by contrary and extraneous elements. The clarity of art—the precise evocation of mood in the novel, or of summer twilight in a painting—is like waking to a bright landscape after a long fitful slumber, or the fragrance of chicken soup after a week of head cold.”
—Yi-Fu Tuan (b. 1930)