List of software palettes#Adaptive palettes

These are selections of colors officially employed as system palettes in some popular operating systems for personal computers that support 8-bit displays.

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Used by these platforms 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.

:Image:Windows 16colors palette.png

The corresponding indices into this palette are:

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In 256-color mode, there are four additional standard Windows colors, twenty system reserved colors in total;[https://web.archive.org/web/*/http://download.microsoft.com/download/platformsdk/sample43/1/W95/EN-US/Palman.exe The Palette Manager: How and Why It Does What It Does], the article is in Windows Write file inside self-extracting archive.{{Cite web|url=https://docs.microsoft.com/en-us/windows/desktop/opengl/palettes-and-the-palette-manager|title = Palettes and the Palette Manager - Win32 apps| date=23 August 2019 }} 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.

Since Windows 95, these additional colors can be changed by the system when a color scheme needs custom colors,{{Cite web|url=https://www.compuphase.com/palette.htm|title=The Microsoft Windows Palette Manager}} reducing their utility as static, unchanging palette entries.

:Image:Windows 20colors palette.png

The complete 20-color Windows system palette is:

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When Apple Computer introduced the Macintosh II in 1987, this 16-color palette was included in System 4.1.

:Image:Mac 16colors palette.svg

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Acorn RISC OS 2.x and 3.x provided this 16-color palette:[http://www.houseofmabel.com/puters/RISCOS2/ House of Mabel: RISC OS 2]

:Image:RiscOS 16colors palette.svg

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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.

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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.

:Image:RGB 6levels palette.png

Systems that use this software palette are:

• Web-safe colors
• Apple Macintosh 256 color default palette. It also contains four gradients of ten shades each for gray, red, green and blue.

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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.

:Image:RGB 6-7-6levels palette.png

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.

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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.

:Image:RGB 6-8-5levels palette.png

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|date=April 2009}}, in a compromise between the RGB arrangement based in the human eye's sensibility and a sufficient remaining palette entries for another purposes.

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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:

:Image:RGB 8-8-4-levels palette.png

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.

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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:

:Image:Grayscale 8bits palette.png

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.

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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:

:Image:Adaptative 8bits palette.png

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:

:Image:Incorrect 8bits palette sample image.png

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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:

:Image:False colors palette.png

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.

• Palette (computing)
• Indexed color
• Color Lookup Table
• Color depth
• Web colors
• X11 color names

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Category:Computer output devices