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.
Acorn RISC OS 2.x and 3.x provided this 16-color palette:[4] 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.
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.
Levels are chosen in function of sensibility of the normal human eye to every primary color.
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.
Software using this palette must draw their user interface elements with the same colors used to show pictures.
Palettes made of a continuous color gradient from darkest to lightest arbitrary hues.
The relationship between the original luminance and the mapped one can vary, but the lighting scale is preserved along all the palette entries.
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.
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.