Color depth is a computer graphics term describing the number of bits used to represent the color of a single pixel in a bitmapped image or video frame buffer. This concept is also known as bits per pixel (bpp), particularly when specified along with the number of bits used. Higher color depth gives a broader range of distinct colors. Computer graphics is a sub-field of computer science and is concerned with digitally synthesizing and manipulating visual content. ... This article is about the unit of information. ... Color is an important part of the visual arts. ... This example shows an image with a portion greatly enlarged, in which the individual pixels are rendered as little squares and can easily be seen. ... For the use of the term raster in radio regulation, see frequency raster. ... The framebuffer is a part of RAM in a computer allocated to hold the graphics information for one frame or picture. ...

Indexed color

A 2-bit indexed-color image. The color of each pixel is represented by a number; each number corresponds to a color in the palette.

With relatively low color depth, the stored value is typically an index into a color map or palette. The colors available in the palette itself may be fixed by the hardware or modifiable. Modifiable palettes are sometimes referred to as pseudocolor palettes. Image File history File links Illustration of how an indexed palette works. ... A palette, in computer graphics, is a designated subset of the total range of colors supported by a computer graphics system. ...

• 1-bit color (2¹ = 2 colors) monochrome, often black and white
• 2-bit color (2² = 4 colors) CGA
• 4-bit color (2⁴ = 16 colors) as used by EGA and by the least common denominator VGA standard at higher resolution
• 5-bit color (2⁵ = 32 colors) Original Amiga chipset
• 6-bit color (2⁶ = 64 colors) Original Amiga chipset
• 8-bit color (2⁸ = 256 colors) Most early color Unix workstations, VGA at low resolution, Super VGA, AGA
• 12-bit color (2¹² = 4096 colors) some Silicon Graphics systems, Color NeXTstation systems, and Amiga systems in HAM mode.

Old graphics chips, particularly those used in home computers and video game consoles, often feature an additional level of palette mapping in order to increase the maximum number of simultaneously displayed colors. For example, in the ZX Spectrum, the picture is stored in a two-color format, but these two colors can be separately defined for each rectangular block of 8x8 pixels. 1-bit colour graphics is a method of storing image information in a computers memory or in an image file, such that each pixel is represented by one bit. ... A photograph of a sign in grayscale The same photograph in black and white Monochrome comes from the two Greek words mono (μωνο, meaning one), and chroma (χρωμα, meaning surface or the color of the skin). A monochromatic object has a single color. ... The Color Graphics Adapter (CGA), introduced in 1981, was IBMs first color graphics card, and the first color computer display standard for the IBM PC. The standard IBM CGA graphics card was equipped with 16 kilobytes of video memory. ... The Enhanced Graphics Adapter (EGA) is the IBM PC computer display standard specification located between CGA and VGA in terms of graphics performance (that is, colour and space resolution). ... Video Graphics Array (VGA) is a computer display standard first marketed in 1987 by IBM. VGA belongs to a family of earlier IBM video standards and largely remains backward compatible with them. ... The Original Chip Set (OCS) was a chipset used in the earliest Commodore Amiga computers. ... The Original Chip Set (OCS) was a chipset used in the earliest Commodore Amiga computers. ... 8-bit colour graphics is a method of storing image information in a computers memory or in an image file, such that each pixel is represented by one 8-bit byte. ... Video Graphics Array (VGA) is a computer display standard first marketed in 1987 by IBM. VGA belongs to a family of earlier IBM video standards and largely remains backward compatible with them. ... Super Video Graphics Array, almost always abbreviated to Super VGA or just SVGA is a broad term that covers a wide range of computer display standards. ... Advanced Graphics Architecture (AGA) was the name used for the improved graphics chipset of the third generation Amiga computers at the beginning of the 1990s. ... Silicon Graphics, Inc. ... The NeXT logo, designed by Paul Rand. ... The original Amiga 1000 (1985) with various peripherals The Amiga is a family of home/personal computers originally developed by Amiga Corporation as an advanced home entertainment and productivity machine. ... A 4,096 color HAM picture from 1989 Hold-and-Modify (more commonly known as HAM) is a screenmode of the Commodore Amiga computer. ... The ZX Spectrum is a home computer released in the United Kingdom in 1982 by Sinclair Research Ltd. ...

1 bit

4 bits

8 bits

Truecolor (24+ bits)

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Direct color

As the number of bits increases, the number of possible colors becomes impractically large for a color map (a 20 bit depth would require more memory to store the colormap than is required to store the pixels themselves). So in higher color depths, the color value typically directly encodes relative brightnesses of red, green, and blue to specify a color in the RGB color model. A representation of additive color mixing—In CRT based (analog electronics) television three color electron guns are used to stimulate such an arrangement of phosphorescent coatings of the glass, the resultant reemission of photons providing the image seen by the eye. ...

8-bit direct color

A very limited but true direct color system, there are 3 bits (8 possible levels) for both the R and G components, and the two remaining bits in the byte pixel to the B component (four levels), enabling 256 (8 × 8 × 4) different colors. The normal human eye is less sensitive to the blue component than to the red or green, so it is assigned one bit less than the others. Used, at least, in the MSX2 system series of computers in the early 1990's. MSX2 may refer to: The second generation of the MSX home computers Homeo box homolog 2 Protein This article consisting of a 4-letter acronym or initialism is a disambiguation page — a list of pages that otherwise might share the same title. ... Events and trends Technology Explosive growth of the Internet; decrease in the cost of computers and other technology Reduction in size and cost of mobile phones leads to a massive surge in their popularity Year 2000 problem (commonly known as Y2K) Microsoft Windows operating system becomes virtually ubiquitous on IBM...

Do not confuse with an indexed color depth of 8bpp (although it can be simulated in such systems selecting the adequate table).

12-bit direct color

In 12-bit direct color, there are 4 bits (16 possible levels) for each of the R, G, and B components, enabling 4,096 (16 × 16 × 16) different colors. This color depth is sometimes used in devices with a color display, such as mobile telephones and other equipment.

HighColor

Highcolor or HiColor is considered sufficient to provide life-like colors, and is encoded using either 15 or 16 bits: Highcolour (or Hicolour, Highcolor, Hicolor, Thousands on a Macintosh) graphics is a method of storing image information in a computers memory such that each pixel is represented by two bytes. ...

• 15-bit uses 5 bits to represent red, 5 for green, and 5 for blue. Since 2⁵ is 32 there are 32 levels of each color which can therefore be combined to give a total of 32,768 (32 × 32 × 32) mixed colors .

• 16-bit color uses 5 bits to represent red, 5 bits to represent blue, but (since the human eye is more sensitive to the color green) uses 6 bits to represent 64 levels of green. These can therefore be combined to give 65,536 (32 × 64 × 32) mixed colors. Sixteen-bit color is referred to as "thousands of colors" on Macintosh systems.

LCD Displays

• Some modern LCD displays use dithered 18-bit color (64 × 64 × 64 = 262,144 combinations) to achieve faster transition times, without sacrificing truecolor display levels entirely.

This article or section should be merged with Dither An illustration of dithering. ...

Truecolor

Truecolor can frequently mimic many colors found in the real world, producing 16.7 million distinct colors. This approaches the level at which the human eye can distinguish colors for most photographic images, though image manipulation, some black-and-white images (which are restricted to 256 levels with Truecolor) or "pure" generated images may reveal the limitations. Truecolor (also spelled Truecolour; called Millions on a Macintosh) graphics is a method of storing image information in a computers memory such that each pixel is represented by three or more bytes. ...

• 24-bit Truecolor uses 8 bits to represent red, 8 bits to represent blue, and 8 bits to represent green. 2⁸ = 256 levels of each of these three colors can therefore be combined to give a total of 16,777,216 mixed colors (256 × 256 × 256). Twenty-four-bit color is referred to as "millions of colors" on Macintosh systems.

32-bit color

"32-bit color" is a misnomer when regarding display color depth. A common misconception is that 32-bit color produces 4,294,967,296 distinct colors.

In reality, 32-bit color actually refers to 24-bit color (Truecolor) with an additional 8 bits, either as empty padding space or to represent an alpha channel. Considering red, green, and blue use the same amount of bits for their respective color (with the exception of 16-bit color), the total bits used will be a multiple of 3: like 15-bit color (5 bits each) and 24-bit color (8 bits each). The reason for using empty space is that all but the newest modern computers process data internally in units of 32 bits; as such, using this amount for each pixel can allow speed optimizations, but increasing the installed video memory. In computer graphics, alpha compositing is often useful to render image elements in separate passes, and then combine the resulting multiple 2D images into a single, final image in a process called compositing. ...

Beyond truecolor

In the late 1990s, some high-end graphics hardware and scanners, such as from SGI, started to use more than 8 bits per channel, such as 12 or 16. This has never become common, as the gain in color resolution is almost invisible – 10 bits per channel seem to be enough to reach the absolute limits of human vision under almost all circumstances^{[citation needed]}. Silicon Graphics, Inc. ...

However, professional-quality image manipulation software has started to employ 16 bits per color channel for internal storage, providing protection against accumulating rounding errors when multiple consecutive manipulations are performed on a picture. A round-off error is the difference between the calculated approximation of a number and its exact mathematical value. ...

For extended dynamic range imaging, including high dynamic range imaging (HDRI), floating point numbers are used to describe numbers in excess of 'full' white and black. This allows an image to describe accurately the intensity of the sun and deep shadows in the same colour space. Various models are used to describe these ranges, many employing 32 bit accuracy per channel. A new format is the ILM "half" using 16-bit floating point numbers, it appears this is a much better use of 16 bits than using 16-bit integers and is likely to replace it entirely as hardware becomes fast enough to support it. An example of a rendering of an HDRI image into an 8 bit JPEG. This image is of the Tower Bridge in Sacramento, California. ... Industrial Light & Magic original logo, designed by Drew Struzan Industrial Light & Magic (ILM) is a motion picture special visual effects company, founded in May 1975 by George Lucas and owned by Lucasfilm Ltd. ... In computing, half precision is a computer numbering format that occupies only half of one storage locations in computer memory at address. ...

Television Color

Most of today's TVs and computer screens form images by varying the intensity of just three primary colors: red, green, and blue. Bright yellow, for example, is composed of equal parts red and green, with no blue component. However, this is only an approximation, and is not as saturated as actual yellow light. For this reason, recent technologies such as, Texas Instruments's BrilliantColor augment the typical red, green, and blue channels with up to three others: cyan, magenta and yellow. Mitsubishi and Samsung, among others, use this technology in some TV sets. Assuming that 8 bits are used per color, such six-color images would have a color depth of 48 bits. Texas Instruments (NYSE: TXN), better known in the electronics industry (and popularly) as TI, is an American company based in Dallas, Texas, USA, renowned for developing and commercializing semiconductor and computer technology. ... Mitsubishi Logo The Mitsubishi Group ), Mitsubishi Group of Companies, or Mitsubishi Companies, all refer to a large grouping of independently operated Japanese companies which share the Mitsubishi brand name. ... Samsung Group is one of the largest South Korean business groupings. ...

The ATI FireGL V7350 graphics card supports 40-bit and 64-bit color^[1]. The FireGL range of graphics cards is a series fabricated by ATI for use with CAD (Computer Aided Design) and DCC (Digital Content Creation) programs, usually found in workstations. ... A graphics/video/display card/board/adapter is a computer component designed to convert the logical representation of visual information into a signal that can be used as input for a display medium. ...

See also

• RGB color model
• List of palettes

A representation of additive color mixing—In CRT based (analog electronics) television three color electron guns are used to stimulate such an arrangement of phosphorescent coatings of the glass, the resultant reemission of photons providing the image seen by the eye. ... Original true-color (24-bit) image This is a list of the full color palettes for notable computer graphics hardware. ...

References

1. ^ [Tony] (2006-03-20). ATI unwraps first 1GB graphics card. Hardware.co.uk. Retrieved on 2006-10-03.

For the Manfred Mann album, see 2006 (album). ... March 20 is the 79th day of the year in the Gregorian Calendar (80th in leap years). ... For the Manfred Mann album, see 2006 (album). ... October 3 is the 276th day of the year (277th in leap years) in the Gregorian calendar. ...

External links

• Understanding Bit Depth: Basics and comparison
• Preparing images for mobile devices: Reducing color depth related artifacts on mobile devices
• Banding in low colour resolution workflows: Comparison and recommendations
• Display the color bit depth and screen resolution of your current monitor