![]() The normal human eye has sensibility to the three primary colors in different degrees: the more to the green, the less to the blue. This kind of arrangement is sometimes referred as a uniform palette. This is done by selecting colors in such way that the master palette comprises a full RGB color space "in miniature", limiting the possible levels that the red, green and blue components may have. A solution is to use a unique, common master palette or universal palette, which can be used to display with reasonable accuracy any kind of image. In an application showing many different image thumbnails in a mosaic on screen, the program may not be able to load all the adaptive palettes of every displayed image thumbnail at the same time in the hardware color registers. This way, while the system can potentially reproduce any color in the RGB color space (as long as the 256 color restriction allows), the storage requirement per pixel is lowered from 24 to 8 bits per pixel.Īn adaptive color palette expanding from 2 colors to 256 colors, demonstrating how the image changes (click to see animation). ![]() An example is the 256-color palette commonly used in the GIF file format, in which 256 colors to be used to represent an image are selected from the whole 24 bit color space, each being assigned an 8 bit index. Each possible color is assigned an index, which allows each color to be referenced using less information than needed to fully describe the color. The objective of the usage of smaller palettes via CLUTs is to lower the number of bits per pixel by reducing the set of possible colors that are to be handled at once (often using adaptive methods). The full system palette for such hardware therefore has 2 24 colors. Using this technique, 8 bits per pixel are used to describe the luminance level in each of the RGB channels, therefore 24 bits fully describe the color of each pixel. Images in which colors are indicated by references to a CLUT are called indexed color images.Īs of 2019, the most common image colorspace in graphics cards is the RGB color model with 8 bits per pixel color depth. By referencing the colors via an index, which takes less information than needed to describe the actual colors in the color space, this technique aims to reduce data usage, including processing, transfer bandwidth, RAM usage, and storage. ![]() In some systems, the palette is fixed by the hardware design, and in others it is dynamic, typically implemented via a color lookup table (CLUT), a correspondence table in which selected colors from a certain color space's color reproduction range are assigned an index, by which they can be referenced. In computer graphics, a palette is the set of available colors from which an image can be made. The palette used in the image, shown rotating about the RGB color space.
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