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Gamma Correction
Gamma correction or gamma is a Nonlinearity, nonlinear operation used to encode and decode Relative luminance, luminance or CIE 1931 color space#Tristimulus values, tristimulus values in video or still image systems. Gamma correction is, in the simplest cases, defined by the following Power law, power-law expression: : V_\text = A V_\text^\gamma, where the non-negative real input value V_\text is raised to the power \gamma and multiplied by the constant ''A'' to get the output value V_\text. In the common case of , inputs and outputs are typically in the range 0–1. A gamma value \gamma 1 is called a ''decoding gamma'', and the application of the expansive power-law nonlinearity is called gamma expansion. Explanation Gamma encoding of images is used to optimize the usage of bits when encoding an image, or bandwidth used to transport an image, by taking advantage of the non-linear manner in which humans perceive light and color. The human perception of brightness (lightness), un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primary Color
Primary colors are colorants or colored lights that can be mixed in varying amounts to produce a gamut of colors. This is the essential method used to create the perception of a broad range of colors in, e.g., electronic displays, color printing, and paintings. Perceptions associated with a given combination of primary colors can be predicted by an appropriate mixing model (e.g., additive, subtractive) that uses the physics of how light interacts with physical media, and ultimately the retina to be able to accurately display the intended colors. The most common color mixing models are the additive primary colors (red, green, blue) and the subtractive primary colors (cyan, magenta, yellow). Red, yellow and blue are also commonly taught as primary colors (usually in the context of subtractive color mixing as opposed to additive color mixing), despite some criticism due to its lack of scientific basis. Primary colors can also be conceptual (not necessarily real), either as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NTSC
NTSC (from National Television System Committee) is the first American standard for analog television, published and adopted in 1941. In 1961, it was assigned the designation System M. It is also known as EIA standard 170. In 1953, a second NTSC standard was adopted, which allowed for color television broadcast compatible with the existing stock of black-and-white receivers. It is one of three major color formats for analog television, the others being PAL and SECAM. ''NTSC color'' is usually associated with the System M; this combination is sometimes called NTSC II. The only other broadcast television system to use NTSC color was the System J. Brazil used System M with PAL color. Vietnam, Cambodia and Laos used System M with SECAM color – Vietnam later started using PAL in the early 1990s. The NTSC/System M standard was used in most of the Americas (except Argentina, Brazil, Paraguay, and Uruguay), Myanmar, South Korea, Taiwan, Philippines, Japan, and some Pacific Isl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CCIR System N
CCIR System N is an analog broadcast television system introduced in 1951 and adopted by Argentina, Paraguay and Uruguay, paired with the PAL color system ( PAL-N) since 1980. It employs the 625 line/50 field per second waveform of CCIR Systems B/ G, D/ K, and I, but on a 6 MHz channel with a chrominance subcarrier frequency of 3.582056 MHz (similar to NTSC). Specifications The general System N specifications are listed below:Reference Data for Radio Engineers, ITT Howard W.Sams Co., New York, 1977, section 30 * Frame rate: 25 Hz * Interlace: 2/1 * Field rate: 50 Hz * Lines/frame: 625 * Line rate: 15.625 kHz * Visual bandwidth: 4.2 MHz * Vision modulation: Negative * Preemphasis: 75 μs * Sound modulation: FM * Sound offset: +4.5 MHz * Channel bandwidth: 6 MHz See also * PAL * PAL-N * Broadcast television systems * Multichannel Television Sound Multichannel Television Sound (MTS) is the method of encoding three additi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CCIR System M
CCIR System M, sometimes called 525–line, NTSC, NTSC-M, or CCIR-M, is the analog broadcast television system approved by the FCC (upon recommendation by the National Television System Committee - NTSC) for use in the United States since July 1, 1941, replacing the 441-line TV system introduced in 1938. It is also known as EIA standard 170. System M comprises a total of 525 interlaced lines of video, of which 486 contain the image information, at 30 frames per second. Video is amplitude modulated and audio is frequency modulated, with a total bandwidth of 6 MHz for each channel, including a guard band. It was also adopted in the Americas and Caribbean; Myanmar, Philippines, South Korea, Taiwan and Japan (here with minor differences, informally referred to as ''System J)''. System M doesn't specify a color system, but NTSC color encoding was normally used, with some exceptions: NTSC-J in Japan, PAL-M in Brazil and SECAM-M in Cambodia, Laos and Vietnam (see '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eastman Kodak Company
The Eastman Kodak Company, referred to simply as Kodak (), is an American public company that produces various products related to its historic basis in film photography. The company is headquartered in Rochester, New York, and is incorporated in New Jersey. It is best known for photographic film products, which it brought to a mass market for the first time. Kodak began as a partnership between George Eastman and Henry A. Strong to develop a film roll camera. After the release of the Kodak camera, Eastman Kodak was incorporated on May 23, 1892. Under Eastman's direction, the company became one of the world's largest film and camera manufacturers, and also developed a model of welfare capitalism and a close relationship with the city of Rochester. During most of the 20th century, Kodak held a dominant position in photographic film, and produced a number of technological innovations through heavy investment in research and development at Kodak Research Laboratories. Kodak produce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hurter And Driffield
Ferdinand Hurter (1844–1898) and Vero Charles Driffield (1848–1915) were nineteenth-century photographic scientists who brought quantitative scientific practice to photography through the methods of sensitometry and densitometry. Among their other innovations was a photographic exposure estimation device known as an actinograph. See also * H&D speed numbers, originally described in 1890, for film speed Film speed is the measure of a photographic film's sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system introduced in 1974. A closely related system, also known as IS ... measurements References External links A brief history of Hurter and Driffield by Ron Callender in ''Encyclopedia of Nineteenth-century Photography'' 2008 pp.732-4 History of photography {{photo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sensitometry
Sensitometry is the scientific study of light-sensitive materials, especially photographic film. The study has its origins in the work by Ferdinand Hurter and Vero Charles Driffield (circa 1876) with early black-and-white emulsions. They determined how the density of silver produced varied with the amount of light received, and the method and time of development. Details Plots of film density (log of opacity) versus the log of exposure are called characteristic curves, Hurter–Driffield curves, H–D curves, HD curves, H & D curves, D–logE curves, or D–logH curves. At moderate exposures, the overall shape is typically a bit like an "S" slanted so that its base and top are horizontal. There is usually a central region of the HD curve which approximates to a straight line, called the "linear" or "straight-line" portion; the slope of this region is called the gamma. The low end is called the "toe", and at the top, the curve rounds over to form the "shoulder". At extremel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exposure (photography)
In photography, exposure is the amount of light per unit area reaching a frame (photography), frame of photographic film or the surface of an electronic image sensor. It is determined by shutter speed, lens f-number, and scene luminance. Exposure is measured in unit of measurement, units of lux-seconds (symbol lxs), and can be computed from exposure value (EV) and scene luminance in a specified region. An "exposure" is a single shutter cycle. For example, a long-exposure photography, long exposure refers to a single, long shutter cycle to gather enough dim light, whereas a multiple exposure involves a series of shutter cycles, effectively layering a series of photographs in one image. The accumulated ''photometric exposure'' (''H''v) is the same so long as the total exposure time is the same. Definitions Radiant exposure Radiant exposure of a ''surface'', denoted ''H''e ("e" for "energetic", to avoid confusion with Photometry (optics), photometric quantities) and measured in , i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photographic Film
Photographic film is a strip or sheet of transparent film base coated on one side with a gelatin photographic emulsion, emulsion containing microscopically small light-sensitive silver halide crystals. The sizes and other characteristics of the crystals determine the sensitivity, contrast, and image resolution, resolution of the film. Film is typically segmented in ''frames'', that give rise to separate photographs. The emulsion will gradually darken if left exposed to light, but the process is too slow and incomplete to be of any practical use. Instead, a very short exposure (photography), exposure to the image formed by a camera lens is used to produce only a very slight chemical change, proportional to the amount of light absorbed by each crystal. This creates an invisible latent image in the emulsion, which can be chemically photographic processing, developed into a visible photograph. In addition to visible light, all films are sensitive to ultraviolet light, X-rays, gamma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Derivative
In mathematics, the derivative is a fundamental tool that quantifies the sensitivity to change of a function's output with respect to its input. The derivative of a function of a single variable at a chosen input value, when it exists, is the slope of the tangent line to the graph of the function at that point. The tangent line is the best linear approximation of the function near that input value. For this reason, the derivative is often described as the instantaneous rate of change, the ratio of the instantaneous change in the dependent variable to that of the independent variable. The process of finding a derivative is called differentiation. There are multiple different notations for differentiation. '' Leibniz notation'', named after Gottfried Wilhelm Leibniz, is represented as the ratio of two differentials, whereas ''prime notation'' is written by adding a prime mark. Higher order notations represent repeated differentiation, and they are usually denoted in Leib ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
