This is a list of software palettes used by computers. Systems that use a 4-bit or 8-bit pixel depth can display up to 16 or 256 colors simultaneously. Many personal computers in the early 1990 displayed at most 256 different colors, freely selected by software (either by the user or by a program) from their wider hardware's RGB color palette.
Usual selections of colors in limited subsets (generally 16 or 256) of the full palette includes some RGB level arrangements commonly used with the 8-bit palettes as master palettes or universal palettes (i.e., palettes for multipurpose uses).
These are some representative software palettes, but any selection can be made in such of systems.
For specific hardware color palettes, see the List of monochrome and RGB palettes, List of 8-bit computer hardware palettes, the List of 16-bit computer hardware palettes and the List of videogame consoles palettes articles.
Each palette is represented by an array of color patches. A one-pixel size version appears below each palette, to make it easy to compare palette sizes.
For each unique palette, an image color test chart and sample image (truecolor original follows) rendered with that palette (without dithering) are given. The test chart shows the full 8-bit, 256 levels of the red, green, and blue (RGB) primary colors and cyan, magenta, and yellow complementary colors, along with a full 8-bit, 256 levels grayscale. Gradients of RGB intermediate colors (orange, lime green, sea green, sky blue, violet and fuchsia), and a full hue spectrum are also present. Color charts are not gamma corrected.
These elements illustrate the color depth and distribution of the colors of any given palette, and the sample image indicates how the color selection of such palettes could represent real-life images.
These are selections of colors officially employed as system palettes in some popular operating systems for personal computers that support 8-bit displays.
Used by this platform as a roughly backward compatible palette for the CGA, EGA and VGA text modes, but with colors arranged in a different order. Also is the default palette for 16 color icons.
The corresponding indices into this palette are:
|0 — black||8 — gray|
|1 — maroon||9 — red|
|2 — green||10 — lime|
|3 — olive||11 — yellow|
|4 — navy||12 — blue|
|5 — purple||13 — fuchsia|
|6 — teal||14 — aqua|
|7 — silver||15 — white|
In 256-color mode, there are four additional standard Windows colors, twenty system reserved colors in total;thus the system leaves 236 palette indexes free for applications to use. The system color entries inside a 256-color palette table are the first ten plus the last ten. In any case, the additional system colors do not seem to add a sharp color richness: they are only some intermediate shades of grayish colors.
The complete 20-color Windows' system palette is:
|0 — black||246 — cream|
|1 — dark red||247 — medium grey|
|2 — dark green||248 — dark grey|
|3 — dark yellow||249 — red|
|4 — dark blue||250 — green|
|5 — dark magenta||251 — yellow|
|6 — dark cyan||252 — blue|
|7 — light grey||253 — magenta|
|8 — money green||254 — cyan|
|9 — sky blue||255 — white|
When Apple Computer introduced the Macintosh II in 1987, this 16-color palette was included in System 4.1.
|0 — white||8 — green|
|1 — yellow||9 — dark green|
|2 — orange||10 — brown|
|3 — red||11 — tan|
|4 — magenta||12 — light grey|
|5 — purple||13 — medium grey|
|6 — blue||14 — dark grey|
|7 — cyan||15 — black|
Acorn RISC OS 2.x and 3.x provided this 16-color palette:
|0 — white||8 — dark blue|
|1 — grey #1||9 — yellow|
|2 — grey #2||10 — green|
|3 — grey #3||11 — red|
|4 — grey #4||12 — beige|
|5 — grey #5||13 — dark green|
|6 — grey #6||14 — orange|
|7 — black||15 — light blue|
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These are selections of colors based in evenly ordered RGB levels which provide complete RGB combinations, mainly used as master palettes to display any kind of image within the limitations of the 8-bit pixel depth.
Having six levels for every primary, with 6³ = 216 combinations. The index can be addressed by (36×R)+(6×G)+B, with all R, G and B values in a range from 0 to 5. Intended as homogeneous RGB cube, it gives six true grays. Also, there is room for another sorts of 40 colors, so operating systems or programs can add extra colors.
Systems that use this software palette are:
This palette is constructed with six levels for red and blue primaries and seven levels for the green primary, giving 6×7×6 = 252 combinations. The index can be addressed by (42×R)+(6×G)+B, with R and B values in a range from 0 to 5 and G in a range from 0 to 6. The same case as the former, but with an added level of green due to the greater sensibility of the normal human eye to this frequency.
It does not provide true grays, but remaining indexes can be filled with four intermediate grays. In any case, there is little room for any other color.
This palette is constructed with six levels for red, eight levels for green and five levels for the blue primaries, giving 6×8×5 = 240 combinations. The index can be addressed by (40×R)+(5×G)+B, with R ranging from 0 to 5, G from 0 to 7 and B from 0 to 4. Levels are chosen in function of sensibility of the normal human eye to every primary color.
Also, it does not provide true grays. Remaining indexes can be filled with sixteen intermediate grays or other fixed colors. In fact, this is the best balanced RGB master software palette[ citation needed ], in a compromise between the RGB arrangement based in the human eye's sensibility and a sufficient remaining palette entries for another purposes.
The 8-8-4 level RGB use eight levels for each of the red and green color components (3+3 high order bits), and four levels (2 low order bits) for the blue component, due to the lesser sensitivity of the normal human eye to this primary color. This results in an 8×8×4 = 256-color palette as follows:
This RGB software palette occupies the full 8-bit range of possible palette entries, so there is no room for other fixed colors. Software using this palette must draw their user interface elements with the same colors used to show pictures. Also again, it does not provide true grays.
Simple palette made doing every triplet RGB primaries having equal values as a continuous gradient from black to white through the full available palette entries. Here is the 8-bit, 256 levels palette:
Used to display pure grayscale TIFF or JPEG images, for example.
Palettes made of a continuous color gradient from darkest to lightest arbitrary hues. The pixel data is treated as if it were grayscale, but the color table plays with RGB color combinations, not only gray. The relationship between the original luminance and the mapped one can vary, but the lighting scale is preserved along all the palette entries.
One very common case of such palettes is the sepia tone palette, which gives an image an old fashioned and aged look (left). Another gradient example, based on blue hues, is presented here (right), but any hue or mixing of hues can be used. Many cell phones with built-in cameras have options to take colorized photos using this technique.
Those whose whole number of available indexes are filled with RGB combinations selected from the statistical order of appearance (usually balanced) of a concrete full true color original image. There exist many algorithms to pick the colors through color quantization; one well known is the Heckbert's median-cut algorithm. Here is the 8-bit, 256 color palette used with the color test chart and the image sample above:
Adaptive palettes only work well with a unique image. Trying to display different images with adaptive palettes over an 8-bit display usually results in only one image with correct colors, because the images have different palettes and only one can be displayed at a time. Here is an example of what happens when an indexed color image is displayed with any color palette that is not its own adaptive palette:
Arbitrary gradient color scales, usually 256 shades, with no relationship with real colors of a given image. They are employed to artificially colorize a grayscale image to reveal details and/or to map the pixel level values to amounts of some physical magnitude (potential, temperature, altitude, etc.)
Note, in the example above, that new details can be seen as blue over magenta in the background's dark areas of the original photograph.
Here is the 8-bit, 256 color gradient palette used with the color test chart and the image sample above:
There exist many false color palettes, some of them standardized, used mainly in scientific applications: astronomy and radioastronomy, satellite land imaging, thermography, study of materials, tomography and magnetic resonance imaging in medicine, etc.
Portable Network Graphics is a raster-graphics file format that supports lossless data compression. PNG was developed as an improved, non-patented replacement for Graphics Interchange Format (GIF).
PCX, standing for PiCture eXchange, is an image file format developed by the now-defunct ZSoft Corporation of Marietta, Georgia, United States. It was the native file format for PC Paintbrush and became one of the first widely accepted DOS imaging standards, although it has since been succeeded by more sophisticated image formats, such as BMP, JPEG, and PNG. PCX files commonly stored palette-indexed images ranging from 2 or 4 colors to 16 and 256 colors, although the format has been extended to record true-color (24-bit) images as well.
The RGB color model is an additive color model in which red, green, and blue 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.
High color graphics is a method of storing image information in a computer's memory such that each pixel is represented by two bytes. Usually the color is represented by all 16 bits, but some devices also support 15-bit high color.
The Enhanced Graphics Adapter (EGA) is an IBM PC computer display standard from 1984 that superseded and exceeded the capabilities of the CGA standard introduced with the original IBM PC, and was itself superseded by the VGA standard in 1987.
The BMP file format, also known as bitmap image file, device independent bitmap (DIB) file format and bitmap, is a raster graphics image file format used to store bitmap digital images, independently of the display device, especially on Microsoft Windows and OS/2 operating systems.
Color depth or colour depth, also known as bit depth, is either the number of bits used to indicate the color of a single pixel, in a bitmapped image or video framebuffer, or the number of bits used for each color component of a single pixel. For consumer video standards, such as High Efficiency Video Coding (H.265), the bit depth specifies the number of bits used for each color component. When referring to a pixel, the concept can be defined as bits per pixel (bpp), which specifies the number of bits used. When referring to a color component, the concept can be defined as bits per component, bits per channel, bits per color, and also bits per pixel component, bits per color channel or bits per sample (bps). Color depth is only one aspect of color representation, expressing the precision with which colors can be expressed; the other aspect is how broad a range of colors can be expressed. The definition of both color precision and gamut is accomplished with a color encoding specification which assigns a digital code value to a location in a color space.
In digital photography, computer-generated imagery, and colorimetry, a grayscale or greyscale image is one in which the value of each pixel is a single sample representing only an amount of light; that is, it carries only intensity information. Grayscale images, a kind of black-and-white or gray monochrome, are composed exclusively of shades of gray. The contrast ranges from black at the weakest intensity to white at the strongest.
The Color Graphics Adapter (CGA), originally also called the Color/Graphics Adapter or IBM Color/Graphics Monitor Adapter, introduced in 1981, was IBM's first graphics card and first color display card for the IBM PC. For this reason, it also became that computer's first color computer display standard.
Dither is an intentionally applied form of noise used to randomize quantization error, preventing large-scale patterns such as color banding in images. Dither is routinely used in processing of both digital audio and video data, and is often one of the last stages of mastering audio to a CD.
Hold-And-Modify, usually abbreviated as HAM, is a display mode of the Commodore Amiga computer. It uses a highly unusual technique to express the color of pixels, allowing many more colors to appear on screen than would otherwise be possible. HAM mode was commonly used to display digitized photographs or video frames, bitmap art and occasionally animation. At the time of the Amiga's launch in 1985, this near-photorealistic display was unprecedented for a home computer and it was widely used to demonstrate the Amiga's graphical capability. However, HAM has significant technical limitations which prevent it from being used as a general purpose display mode.
Color digital images are made of pixels, and pixels are made of combinations of primary colors represented by a series of code. A channel in this context is the grayscale image of the same size as a color image, made of just one of these primary colors. For instance, an image from a standard digital camera will have a red, green and blue channel. A grayscale image has just one channel.
In computer graphics, a palette is a finite set of colors in no particular order. Palettes can be optimized to improve image accuracy in the presence of software or hardware constraints.
In computing, indexed color is a technique to manage digital images' colors in a limited fashion, in order to save computer memory and file storage, while speeding up display refresh and file transfers. It is a form of vector quantization compression.
In computer graphics, color quantization or color image quantization is quantization applied to color spaces; it is a process that reduces the number of distinct colors used in an image, usually with the intention that the new image should be as visually similar as possible to the original image. Computer algorithms to perform color quantization on bitmaps have been studied since the 1970s. Color quantization is critical for displaying images with many colors on devices that can only display a limited number of colors, usually due to memory limitations, and enables efficient compression of certain types of images.