gamma(redirected from Gamma (letter))
Also found in: Dictionary, Thesaurus, Medical, Financial.
gamma(gam -ă) (γ) The third letter of the Greek alphabet, used in stellar nomenclature usually to designate the third-brightest star in a constellation or sometimes to indicate a star's position in a group.
(1) A conventional unit that is sometimes used for measurements of small masses: 1 gamma = 10-6 g. The designation “microgram” (μg) is more frequently used than “gamma.”
(2) The name of a hundred-thousandth part of an oersted (the unit of magnetic field strength in the cgs system of units) that is used mainly for measurements of terrestrial magnetism and cosmic magnetic fields. It is designated by y.
the quantitative characteristic of the ability of photographic material to transmit the difference in exposure H of various parts of a photographic image by the difference in the optical density D of the parts. The gamma is equal to the tangent of the angle of inclination to the axis log H of the straight portion of the performance curve of the material (provided that the scales of the axes log H and D are identical). Other conditions being equal, the gamma characterizes the uniformity of the silver halide crystals of the photographic emulsion with respect to light sensitivity. As a rule, it is greater for low-sensitivity positive materials and less for high-sensitivity negative materials. The gamma is one of the most important sensitometric parameters of a photographic material.
["GAMMA 3.3 for MPS/MPSX, IBM System:/360", Bonnor & Moore Assocs (Mar 1975)].
2. A high-level parallel language.
[Research Directions in High-Level Parallel Languages, LeMetayer ed, Springer 1992].
gammaGamma is a number that represents the relationship between digital pixels and luminance, which is inherently nonlinear. For years, there has been a misconception that gamma had to be corrected due to the inherent deficiency in earlier CRT monitors. In fact, the CRT generated almost the inverse of a human's perception of luminance and thus actually evened out this relationship.
A gamma correction number is applied to ensure that the digital pixels produce a uniform luminance across the entire tonal realm from dark to bright, especially in the midtones. Because LCD monitors were designed to emulate the CRT's gamma, gamma correction is still used. With gamma correction, eight bits per pixel is sufficient; otherwise, 11 bits per pixel would be required. See color depth and pixel.