List of monochrome and RGB color formats


This list of monochrome and RGB palettes includes generic repertoires of colors to produce black-and-white and RGB color pictures by a computer's display hardware. RGB is the most common method to produce colors for displays; so these complete RGB color repertoires have every possible combination of R-G-B triplets within any given maximum number of levels per component.
Each palette is represented by a series of color patches. When the number of colors is low, a 1-pixel-size version of the palette appears below it, for easily comparing relative palette sizes. Huge palettes are given directly in one-color-per-pixel color patches.
For each unique palette, an image color test chart and sample image rendered with that palette are given. The test chart shows the full 256 levels of the red, green, and blue primary colors and cyan, magenta, and yellow complementary colors, along with a full 256-level grayscale. Gradients of RGB intermediate colors, 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 images are not necessarily representative of how the image would be displayed on the original graphics hardware, as the hardware may have additional limitations regarding the maximum display resolution, pixel aspect ratio and color placement.
Implementation of these formats is specific to each machine. Therefore, the number of colors that can be simultaneously displayed in a given text or graphic mode might be different. Also, the actual displayed colors are subject to the output format used - PAL or NTSC, composite or component video, etc. - and might be slightly different.
For simulated images and specific hardware and alternate methods to produce colors other than RGB, see the List of 8-bit computer hardware palettes, the List of 16-bit computer hardware palettes and the List of video game console palettes.
For various software arrangements and sorts of colors, including other possible full RGB arrangements within 8-bit color depth displays, see the List of software palettes.

Monochrome palettes

These palettes only have some shades of gray, from black to white. The general rule is that those palettes have 2n different shades of gray, where n is the number of bits needed to represent a single pixel.

Monochrome (1-bit grayscale)

graphics displays typically have a black background with a white or light gray image, though green and amber monochrome monitors were also common. Such a palette requires only one bit per pixel.
Where photo-realism was desired, these early computer systems had a heavy reliance on dithering to make up for the limits of the technology.
In some systems, as Hercules and CGA graphic cards for the IBM PC, a bit value of 1 represents white pixels and a value of 0 the black ones ; others, like the Atari ST and Apple Macintosh with monochrome monitors, a bit value of 0 means a white pixel and a value of 1 means a black pixel, which it approximates to the printing logic.

2-bit Grayscale

In a 2-bit color palette each pixel's value is represented by 2 bits resulting in a 4-value palette.
2-bit dithering:
It has black, white and two intermediate levels of gray as follows:
A monochrome 2-bit palette is used on:
In a 4-bit color palette each pixel's value is represented by 4 bits resulting in a 16-value palette :
4-bit grayscale dithering does a fairly good job of reducing visible banding of the level changes:
A monochrome 4-bit palette is used on:
In an 8-bit color palette each pixel's value is represented by 8 bits resulting in a 256-value palette. This is usually the maximum number of grays in ordinary monochrome systems; each image pixel occupies a single memory byte.
Most scanners can capture images in 8-bit grayscale, and image file formats like TIFF and JPEG natively support this monochrome palette size.
Alpha channels employed for video overlay also use this palette. The gray level indicates the opacity of the blended image pixel over the background image pixel.

Dichrome palettes

16-bit RG palette

The RG or red–green color space is a color space that uses only two primary colors: red and green. It was used on early color processes for films.
It was used as an additive format, similar to the RGB color model but without a blue channel, on processes such as Kinemacolor, Prizma, Technicolor I, Raycol, etc., producing shades of black, red, green and yellow. Alternatively, it was used as a subtractive format on Brewster Color I, Kodachrome I, Prizma II, Technicolor II, etc., producing shades of transparent, red, green and black.
Until recently, its primary use was in low-cost light-emitting diode displays in which red and green tended to be far more common than the still nascent blue LED technology, but full-color LEDs with blue have become more common in recent years.
ColorCode 3-D, a anaglyph stereoscopic color scheme, uses the RG color space to simulate a broad spectrum of color in one eye, while the blue portion of the spectrum transmits a black-and-white image to the other eye to give depth perception.

16-bit RB palette

16-bit GB palette

Regular RGB palettes

Here are grouped those full RGB hardware palettes that have the same number of binary levels for every red, green and blue components using the full RGB color model. Thus, the total number of colors are always the number of possible levels by component, n, raised to a power of 3: n×''n×n'' = n3.

3-bit RGB

3-bit RGB dithering:
Systems with a 3-bit RGB palette use 1 bit for each of the red, green and blue color components. That is, each component is either "on" or "off" with no intermediate states. This results in an 8-color palette that has black, white, the three RGB primary colors red, green and blue and their correspondent complementary colors cyan, magenta and yellow as follows:
The color indices vary between implementations; therefore, index numbers are not given.
The 3-bit RGB palette is used by:
  • Text terminals following the ECMA-48 standard
  • World System Teletext Level 1/1.5
  • Videotex
  • Oric computers
  • BBC Micro
  • PC-8801
  • PC-9801
  • Sharp X1
  • Sharp MZ 700
  • FM-7, FM New 7, FM 77
  • Sinclair QL
  • Space Invaders Part II
  • Macintosh SE
  • Atari 2600
  • Color Maximite
  • Arcadia 2001
  • PV-1000
  • Monkey Magic
  • VIC-20
  • Mouse Trap
  • Sanyo MBC-550 series
  • Windows 1.0

    6-bit RGB

Systems with a 6-bit RGB palette use 2 bits for each of the red, green, and blue color components. This results in a 3 = 43 = 64-color palette as follows:
6-bit RGB systems include the following:
Systems with a 9-bit RGB palette use 3 bits for each of the red, green, and blue color components. This results in a 3 = 83 = 512-color palette as follows:
9-bit RGB systems include the following:
  • Atari ST
  • MSX2 computers
  • Sega Genesis video game console,
  • Sega Nomad
  • TurboGrafx-16
  • ZX Spectrum Next
  • The NEC PC-8801 Mk II SR and later models
  • The Mindset computer
  • The Sega Pico

    12-bit RGB

Systems with a 12-bit RGB palette use 4 bits for each of the red, green, and blue color components. This results in a 3 = 163 = 4096-color palette. 12-bit color can be represented with three hexadecimal digits, also known as shorthand hexadecimal form, which is commonly used in web design. The palette is as follows:
12-bit RGB systems include the following:
  • Amiga OCS/ECS
  • Apple IIGS Video Graphics Chip
  • Atari STe
  • Acorn Archimedes
  • E-readers and smartdevices with a Kaleido E-ink display
  • Sega Game Gear
  • Hi-Text Level 2.5+ Teletext
  • Neo Geo Pocket Color
  • Atari Lynx
  • NEC PC-9801 VM/VX models typically equipped with a NEC V30 or better, but before the PC9821 Series.
  • The Sharp X1 Turbo Z Series
  • Fujitsu FM-77AV
  • The Amstrad CPC 664Plus, 6128Plus and GX4000
  • NeXTstation Color and NeXTstation Turbo Color
  • WonderSwan Color
  • Thomson TO8
  • IBM PCs with Professional Graphics Controller
The Allegro library supported in the version 4, an emulated 12-bit color mode example code, using 8-bit indexed color in VGA/SVGA. It used two pixels for each emulated pixel, paired horizontally, and a specifically adapted 256-color palette. One range of the palette was many brightnesses of one primary color, and another range of the other two primaries mixed together at different amounts and brightnesses. It effectively reduced the horizontal resolution by half, but allowed a 12-bit "true color" in DOS and other 8-bit VGA/SVGA modes. The effect also somewhat reduced the total brightness of the screen.