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, not necessarily the total number of such colors that can be simultaneously displayed in a given text or graphic mode of any machine. 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.
For specific hardware and different 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.
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. For simulated sample images for notable computers, see the List of 8-bit computer hardware palettes and List of 16-bit computer hardware palettes articles.

Monochrome palettes

These palettes only have some shades of gray, from black to white, both considered the most possible darker and lighter "grays", respectively. 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)

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

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 have 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:
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:
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:
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.

15-bit RGB

Systems with a 15-bit RGB palette use 5 bits for each of the red, green, and blue color components. This results in a 3 = 323 = 32,768-color palette as follows:
15-bit systems include:
Systems with an 18-bit RGB palette use 6 bits for each of the red, green, and blue color components. This results in a 3 = 643 = 262,144-color palette as follows:
18-bit RGB systems include the following:
Often known as truecolor and millions of colors, 24-bit color is the highest color depth normally used, and is available on most modern display systems and software. Its color palette contains 3 = 2563 = 16,777,216 colors. 24-bit color can be represented with six hexadecimal digits. This is approximately the number of individual colors the human eye can distinguish within the limited gamut of a typical display.
The complete palette needs a squared image of 4,096 pixels wide, and there is not enough room in this page to show it at full.
This can be imagined as 256 stacked squares like the following, every one of them having the same given value for the red component, from 0 to 255.
The color transitions in these patches must be seen as continuous. If you see color stepping inside, then probably your display is using a Highcolor mode or lesser.
This is also the number of colors used in true color image files, like Truevision TGA, TIFF, JPEG and Windows Bitmap, captured with scanners and digital cameras, as well as those created with 3D computer graphics software.
24-bit RGB systems include:
Some newer graphics cards support 30-bit RGB and higher. Its color palette contains 3 = 10243 = 1,073,741,824 colors. However, there are few operating systems or applications that support this mode yet. For some people, it may be hard to distinguish between higher color palettes than 24-bit color offers. However, the range of luminance, or gray scale, offered in a 30-bit color system would have 1,024 levels of luminance rather than the 256 of the common standard 24-bit, to which the human eye is more sensitive than to hue. This reduces the banding effect for gradients across large areas.

Non-regular RGB palettes

These also are full RGB palette repertories, but either they do not have the same number of levels for every red, green and blue components, or they are bit levels based. Nevertheless, all of them are used in very popular personal computers.
For further details on color palettes for these systems, see the article List of 8-bit computer hardware palettes.

4-bit RGBI

The 4-bit RGBI palette is similar to the 3-bit RGB palette but adds one bit for intensity. This allows each of the colors of the 3-bit palette to have a dark and bright variant, potentially giving a total of 23×2 = 16 colors. However, some implementations had only 15 effective colors due to the "dark" and "bright" variations of black being displayed identically.
This 4-bit RGBI schema is used in several platforms with variations, so the table given below is a simple reference for the palette richness, and not an actual implemented palette. For this reason, no numbers are assigned to each color, and color order is arbitrary.
Note that "dark white" is a lighter gray than "bright black" in this example.
The most common use of 4-bit RGBI was on IBM PCs and compatible computers that used a 9-pin DE-9 connector for color output. These computers used a modified "dark yellow" color that appeared to be brown. On displays designed for the IBM PC, setting a color "bright" added ⅓ of the maximum to all three channels' brightness, so the "bright" colors were whiter shades of their 3-bit counterparts. Each of the other bits increased a channel by ⅔, except that dark yellow had only ⅓ green and was therefore brown instead of ochre.
PC graphics standards using this RGBI mode include:
The CGA palette is also used by default by IBM's later EGA, MCGA, and VGA graphics standards for backward compatibility, although these standards allow the palette to be changed as they use analog RGB outputs rather than using digital RGBI. Most notably, the EGA standard used the same DE-9 connector as CGA, and most monitors designed for EGA would treat EGA's 200-line graphics modes as using the CGA color palette to retain compatibility with CGA graphics modes and graphic cards.
The MOS Technology 8563 and 8568 Video Display Controller chips used on the Commodore 128 series for its 80-column mode also used the same palette used on the IBM PC, since these chips were designed to work with existing CGA PC monitors.
Other systems using a variation of the 4-bit RGBI mode include:
The 3-level RGB uses three levels for every red, green and blue color component, resulting in a 33 = 27 colors palette as follows:
This palette is used by:
The 3-3-2 bit RGB use 3 bits for each of the red and green color components, and 2 bits for the blue component, due to the lesser sensitivity of the common human eye to this primary color. This results in an 8×8×4 = 256-color palette as follows:
This palette is used by
Most modern systems support 16-bit color. It is sometimes referred to as Highcolor, medium color or thousands of colors. It utilizes a color palette of 32×64×32 = 65,536 colors. Usually, there are 5 bits allocated for the red and blue color components and 6 bits for the green component, due to the greater sensitivity of the common human eye to this color. This doubles the 15-bit RGB palette.
The 16-bit RGB palette using 6 bits for the green component:
The Atari Falcon and the Extended Graphics Array for IBM PS/2 use the 16-bit RGB palette.
It must be noticed that not all systems using 16-bit color depth employ the 16-bit, 32-64-32 level RGB palette. Platforms like the Sharp X68000 home computer or the Neo Geo video game console employs the 15-bit RGB palette, but the last bit specifies a less significant intensity or luminance. The 16-bit mode of the Truevision TARGA/AT-Vista/NU-Vista graphic cards and its associated TGA file format also uses 15-bit RGB, but it devotes its remaining bit as a simple alpha channel for video overlay. The Atari Falcon can also be switched into a matching mode by setting of an "overlay" bit in the graphics processor mode register when in 16-bit mode, meaning it can actually display in either 15- or 16-bit color depth depending on application.

Color palette comparison side-by-side

Basic color palettes

4-bit grayscale

0x00x10x20x30x40x50x60x70x80x90xA0xB0xC0xD0xE0xF

3-bit RGB

0x00x10x20x30x40x50x60x7

4-bit RGBI

0x00x10x20x30x40x50x60x7
0x80x90xA0xB0xC0xD0xE0xF

Advanced color palettes