Editing RGB color model (section)

====Video framebuffer====
A [[framebuffer]] is a digital device for computers which stores data in the so-called ''video memory'' (comprising an array of [[Video RAM#Video DRAM (VRAM)|Video RAM]] or similar [[integrated circuit|chips]]). This data goes either to three [[digital-to-analog converter]]s (DACs) (for analog monitors), one per primary color or directly to digital monitors. Driven by [[software]], the [[central processing unit|CPU]] (or other specialized chips) write the appropriate [[byte]]s into the video memory to define the image. Modern systems encode pixel color values by devoting 8&nbsp;[[bit]]s to each of the R, G, and B components. RGB information can be either carried directly by the pixel bits themselves or provided by a separate '''[[color look-up table]]''' ('''CLUT''') if [[indexed color]] graphic modes are used.

A CLUT is a specialized [[random-access memory|RAM]] that stores R, G, and B values that define specific colors. Each color has its own address (index)—consider it as a descriptive reference number that provides that specific color when the image needs it. The content of the CLUT is much like a palette of colors. Image data that uses indexed color specifies addresses within the CLUT to provide the required R, G, and B values for each specific pixel, one pixel at a time. Of course, before displaying, the CLUT has to be loaded with R, G, and B values that define the palette of colors required for each image to be rendered. Some video applications store such palettes in [[PAL file]]s ([[Age of Empires (video game)|''Age of Empires'']] game, for example, uses over half-a-dozen<ref>By directory search</ref>) and can combine CLUTs on screen.

;RGB24 and RGB32
This indirect scheme restricts the number of available colors in an image CLUT—typically 256-cubed (8&nbsp;bits in three [[color channel]]s with values of 0–255)—although each color in the RGB24 CLUT table has only 8&nbsp;bits representing 256 codes for each of the R, G, and B primaries, making 16,777,216 possible colors. However, the advantage is that an indexed-color image file can be significantly smaller than it would be with only 8&nbsp;bits per pixel for each primary.

Modern storage, however, is far less costly, greatly reducing the need to minimize image file size. By using an appropriate combination of red, green, and blue intensities, many colors can be displayed. Current typical [[display adapter]]s use up to [[24-bit color|24&nbsp;bit]]s of information for each pixel: 8-bit per component multiplied by three components (see the [[#Numeric representations|Numeric representations]] section below (24&nbsp;bits&nbsp;=&nbsp;256<sup>3</sup>, each primary value of 8&nbsp;bits with values of 0–255). With this system, 16,777,216 (256<sup>3</sup> or 2<sup>24</sup>) discrete combinations of R, G, and B values are allowed, providing millions of different (though not necessarily distinguishable) hue, saturation and [[lightness (color)|lightness]] shades. Increased shading has been implemented in various ways, some formats such as [[Portable Network Graphics|.png]] and [[Truevision TGA|.tga]] files among others using a fourth [[grayscale]] color channel as a masking layer, often called '''RGB32'''.

For images with a modest range of brightnesses from the darkest to the lightest, 8&nbsp;bits per primary color provides good-quality images, but extreme images require more bits per primary color as well as the advanced display technology. For more information see [[High Dynamic Range]] (HDR) imaging.