An RG color model is a dichromatic color model represented by red and green primary colors. These can only reproduce a fraction of the colors possible with a trichromatic color space, such as for human color vision.
The name of the model comes from the initials of the two primary colors: red and green. The model may be either additive or subtractive.
It was used to display 3D images using anaglyphs since the 1850s. [1] Despite its shortcomings in color reproduction, the RG model was used in early color processes for films from 1906 to 1929 (Kinemacolor, Prizma, Technicolor, Brewster Color, Kodachrome I and Raycol). [2] [3]
The additive RG color model uses red and green primaries. It was used in several processes during the early innovations of color photography, including Kinemacolor, [4] Prizma, Technicolor I, [5] [6] [7] [8] and Raycol. [9]
The primaries are added together in varying proportions to reproduce a linear gamut of colors, which can reproduce only a fraction of the colors possible with a trichromatic color space.
The appearance of the color gamut changes depending on the primary colors chosen. When the primaries are complementary colors (e.g. red and cyan), then an equal mixture of the primaries will yield a neutral color (gray or white). However, since red and green are not complementary colors, an equal mixture of these primaries will yield yellow, and a neutral color cannot be reproduced by the color space.
Until recently, its primary use was in low-cost LED displays in which red and green LEDs were more common and cheaper than the still nascent blue LED technology. However, this preference no longer applies to modern devices.[ citation needed ] In modern applications, the red and green primaries are equal to the primaries used in typical RGB color spaces. In this case, the RG color model can be achieved by disabling the blue light source.
The subtractive RG color model uses red and green filters for film exposure, but complementary cyan-green (for red) and orange-red (for green) for the developed prints. This allows the generation of white, although the color model cannot achieve black, regardless of the primaries chosen. It was used in several processes during the early innovations of color photography, including on Brewster Color I, [10] [11] [12] [13] Kodachrome I, [14] [15] [16] Prizma II, [17] and Technicolor II. [18] [19] [20]
A similar color model, called RGK adds a black channel, which allows for the reproduction of black and other dark shades. [21] However, it does not allow the reproduction of neutral colors (gray/white) because the primaries are not complementary.
Outside of a few low-cost high-volume applications, such as packaging and labelling, RG and RGK are no longer in use because devices providing larger gamuts such as CMYK are in widespread use.
In 1858, in France, Joseph D'Almeida [ fr ] delivered a report to l'Académie des sciences describing how to project three-dimensional magic lantern slide shows using red and green filters to an audience wearing red and green goggles. [1] Subsequently he was chronicled as being responsible for the first realisation of 3D images using anaglyphs. [22]
Color or colour is the visual perception based on the electromagnetic spectrum. Though color is not an inherent property of matter, color perception is related to an object's light absorption, reflection, emission spectra, and interference. For most humans, colors are perceived in the visible light spectrum with three types of cone cells (trichromacy). Other animals may have a different number of cone cell types or have eyes sensitive to different wavelengths, such as bees that can distinguish ultraviolet, and thus have a different color sensitivity range. Animal perception of color originates from different light wavelength or spectral sensitivity in cone cell types, which is then processed by the brain.
The RGB color model is an additive color model in which the red, green and blue primary colors of light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three additive primary colors, red, green, and blue.
A set of primary colors or primary colours consists of 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 that reflects the physics of how light interacts with physical media, and ultimately the retina. The most common color mixing models are the additive primary colors and the subtractive primary colors. Red, yellow and blue are also commonly taught as primary colours, despite some criticism due to its lack of scientific basis.
Additive color or additive mixing is a property of a color model that predicts the appearance of colors made by coincident component lights, i.e. the perceived color can be predicted by summing the numeric representations of the component colors. Modern formulations of Grassmann's laws describe the additivity in the color perception of light mixtures in terms of algebraic equations. Additive color predicts perception and not any sort of change in the photons of light themselves. These predictions are only applicable in the limited scope of color matching experiments where viewers match small patches of uniform color isolated against a gray or black background.
Complementary colors are pairs of colors which, when combined or mixed, cancel each other out by producing a grayscale color like white or black. When placed next to each other, they create the strongest contrast for those two colors. Complementary colors may also be called "opposite colors".
In color reproduction and colorimetry, a gamut, or color gamut, is a convex set containing the colors that can be accurately represented, i.e. reproduced by an output device or measured by an input device. Devices with a larger gamut can represent more colors. Similarly, gamut may also refer to the colors within a defined color space, which is not linked to a specific device. A trichromatic gamut is often visualized as a color triangle. A less common usage defines gamut as the subset of colors contained within an image, scene or video.
Color theory, or more specifically traditional color theory, is the historical body of knowledge describing the behavior of colors, namely in color mixing, color contrast effects, color harmony, color schemes and color symbolism. Modern color theory is generally referred to as Color science. While there is no clear distinction in scope, traditional color theory tends to be more subjective and have artistic applications, while color science tends to be more objective and have functional applications, such as in chemistry, astronomy or color reproduction. Color theory dates back at least as far as Aristotle's treatise On Colors. A formalization of "color theory" began in the 18th century, initially within a partisan controversy over Isaac Newton's theory of color and the nature of primary colors. By the end of the 19th century, a schism had formed between traditional color theory and color science.
Kinemacolor was the first successful colour motion picture process. Used commercially from 1909 to 1915, it was invented by George Albert Smith in 1906. It was a two-colour additive colour process, photographing a black-and-white film behind alternating red/orange and blue/green filters and projecting them through red and green filters. It was demonstrated several times in 1908 and first shown to the public in 1909. From 1909 on, the process was known and trademarked as Kinemacolor and was marketed by Charles Urban’s Natural Color Kinematograph Company, which sold Kinemacolor licences around the world.
Cinecolor was an early subtractive color-model two-color motion picture process that was based upon the Prizma system of the 1910s and 1920s and the Multicolor system of the late 1920s and the 1930s. It was developed by William T. Crispinel and Alan M. Gundelfinger, and its various formats were in use from 1932 to 1955.
Anaglyph 3D is the stereoscopic 3D effect achieved by means of encoding each eye's image using filters of different colors, typically red and cyan. Anaglyph 3D images contain two differently filtered colored images, one for each eye. When viewed through the "color-coded" "anaglyph glasses", each of the two images is visible to the eye it is intended for, revealing an integrated stereoscopic image. The visual cortex of the brain fuses this into the perception of a three-dimensional scene or composition.
Leopold Godowsky Jr., the oldest son of the famous pianist and composer Leopold Godowsky, was an American violinist and chemist, who together with Leopold Mannes created the first practical color transparency film, Kodachrome.
Color motion picture film refers both to unexposed color photographic film in a format suitable for use in a motion picture camera, and to finished motion picture film, ready for use in a projector, which bears images in color.
Leopold Damrosch Mannes was an American musician, who, together with Leopold Godowsky Jr., created the first practical color transparency film, Kodachrome.
The Prizma Color system was a color motion picture process, invented in 1913 by William Van Doren Kelley and Charles Raleigh. Initially, it was a two-color additive color system, similar to its predecessor, Kinemacolor. However, Kelley eventually transformed Prizma into a bi-pack color system that itself became the predecessor for future color processes such as Multicolor and Cinecolor.
In bipack color photography for motion pictures, two strips of black-and-white 35 mm film, running through the camera emulsion to emulsion, are used to record two regions of the color spectrum, for the purpose of ultimately printing the images, in complementary colors, superimposed on one strip of film. The result is a multicolored projection print that reproduces a useful but limited range of color by the subtractive color method. Bipack processes became commercially practical in the early 1910s when Kodak introduced duplitized film print stock, which facilitated making two-color prints.
A color space is a specific organization of colors. In combination with color profiling supported by various physical devices, it supports reproducible representations of color – whether such representation entails an analog or a digital representation. A color space may be arbitrary, i.e. with physically realized colors assigned to a set of physical color swatches with corresponding assigned color names, or structured with mathematical rigor. A "color space" is a useful conceptual tool for understanding the color capabilities of a particular device or digital file. When trying to reproduce color on another device, color spaces can show whether shadow/highlight detail and color saturation can be retained, and by how much either will be compromised.
Impossible colors are colors that do not appear in ordinary visual functioning. Different color theories suggest different hypothetical colors that humans are incapable of perceiving for one reason or another, and fictional colors are routinely created in popular culture. While some such colors have no basis in reality, phenomena such as cone cell fatigue enable colors to be perceived in certain circumstances that would not be otherwise.
Technicolor is a family of color motion picture processes. The first version, Process 1, was introduced in 1916, and improved versions followed over several decades.