A color space is a specific organization of colors. In combination with physical device profiling, it allows for reproducible representations of color, for example, Adobe RGB and sRGB are two different absolute color spaces, both based on the RGB color model. When defining a color space, the reference standard is the CIELAB or CIEXYZ color spaces. For example, although several specific color spaces are based on the RGB color model, colors can be created in printing with color spaces based on the CMYK color model, using the subtractive primary colors of pigment. The resulting 3-D space provides a position for every possible color that can be created by combining those three pigments. Colors can be created on computer monitors with color spaces based on the RGB color model, a three-dimensional representation would assign each of the three colors to the X, Y, and Z axes. Note that colors generated on given monitor will be limited by the medium, such as the phosphor or filters. Another way of creating colors on a monitor is with an HSL or HSV color space, based on hue, with such a space, the variables are assigned to cylindrical coordinates.
Many color spaces can be represented as three-dimensional values in this manner, but some have more, or fewer dimensions, Color space conversion is the translation of the representation of a color from one basis to another. The RGB color model is implemented in different ways, depending on the capabilities of the system used, by far the most common general-used incarnation as of 2006 is the 24-bit implementation, with 8 bits, or 256 discrete levels of color per channel. Any color space based on such a 24-bit RGB model is limited to a range of 256×256×256 ≈16.7 million colors. Some implementations use 16 bits per component for 48 bits total and this is especially important when working with wide-gamut color spaces, or when a large number of digital filtering algorithms are used consecutively. The same principle applies for any color space based on the color model. CIE1931 XYZ color space was one of the first attempts to produce a space based on measurements of human color perception. The CIERGB color space is a companion of CIE XYZ.
Additional derivatives of CIE XYZ include the CIELUV, CIEUVW, RGB uses additive color mixing, because it describes what kind of light needs to be emitted to produce a given color. RGB stores individual values for red and blue, RGBA is RGB with an additional channel, alpha, to indicate transparency. Common color spaces based on the RGB model include sRGB, Adobe RGB, ProPhoto RGB, scRGB, one starts with a white substrate, and uses ink to subtract color from white to create an image
Adobe Photoshop is a raster graphics editor developed and published by Adobe Systems for macOS and Windows. Photoshop was created in 1988 by Thomas and John Knoll and it can edit and compose raster images in multiple layers and supports masks, alpha compositing and several color models including RGB, CMYK, CIELAB, spot color and duotone. Photoshop has vast support for file formats but uses its own PSD. In addition to graphics, it has limited abilities to edit or render text, vector graphics, 3D graphics. Photoshops featureset can be expanded by Photoshop plug-ins, programs developed and distributed independently of Photoshop that can run inside it, Photoshops naming scheme was initially based on version numbers. Photoshop CS3 through CS6 were distributed in two different editions and Extended, in June 2013, with the introduction of Creative Cloud branding, Photoshops licensing scheme was changed to that of software as a service rental model and the CS suffixes were replaced with CC. Historically, Photoshop was bundled with software such as Adobe ImageReady, Adobe Fireworks, Adobe Bridge, Adobe Device Central.
Alongside Photoshop, Adobe develops and publishes Photoshop Elements, Photoshop Lightroom, Photoshop Express, they are branded as The Adobe Photoshop Family. It is currently a licensed software, Photoshop was developed in 1987 by the American brothers Thomas and John Knoll, who sold the distribution license to Adobe Systems Incorporated in 1988. Thomas Knoll, a PhD student at the University of Michigan, began writing a program on his Macintosh Plus to display images on a monochrome display. This program, called Display, caught the attention of his brother John Knoll, an Industrial Light & Magic employee, Thomas took a six-month break from his studies in 1988 to collaborate with his brother on the program. Thomas renamed the program ImagePro, but the name was already taken, during this time, John traveled to Silicon Valley and gave a demonstration of the program to engineers at Apple and Russell Brown, art director at Adobe. Both showings were successful, and Adobe decided to purchase the license to distribute in September 1988, while John worked on plug-ins in California, Thomas remained in Ann Arbor writing code.
Photoshop 1.0 was released on 19 February 1990 for Macintosh exclusively, the Barneyscan version included advanced color editing features that were stripped from the first Adobe shipped version. The handling of color slowly improved with each release from Adobe, at the time Photoshop 1.0 was released, digital retouching on dedicated high end systems, such as the Scitex, cost around $300 an hour for basic photo retouching. Photoshop files have default file extension as. PSD, which stands for Photoshop Document, a PSD file stores an image with support for most imaging options available in Photoshop. These include layers with masks, text, alpha channels and spot colors, clipping paths and this is in contrast to many other file formats that restrict content to provide streamlined, predictable functionality. A PSD file has a height and width of 30,000 pixels