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64-545: The TIGA standard is independent of resolution and color depth which provides a certain degree of future proofing . This standard was designed for high-end graphics. However, TIGA was not widely adopted. Instead, VESA and Super VGA became the de facto standard for PC graphics devices after the VGA . Texas Instrument's TMS34010 and TMS34020 Graphics System Processors (GSP) were the original TIGA-compliant graphics processors. The primary manufacturers of mainstream TIGA cards for

128-429: A transparent color, in order to perform a simple video overlay : superimposing a given image over a background in such way that some part of the overlapped image obscures the background and the remaining not. Superimposing film/TV titles and credits is a typical application of video overlay. In the image to be superimposed (indexed color is assumed), a given palette entry plays the role of the transparent color. Usually

192-455: A 4-level alpha channel ); the Cineon file format , for example, used this. Some SGI systems had 10- (or more) bit digital-to-analog converters for the video signal and could be set up to interpret data stored this way for display. BMP files define this as one of its formats, and it is called "HiColor" by Microsoft . Video cards with 10 bits per component started coming to market in

256-474: A CLUT are called indexed color images. As of 2019, the most common image colorspace in graphics cards is the RGB color model with 8 bits per pixel color depth . 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. The full system palette for such hardware therefore has 2 colors. The objective of

320-462: A bit depth of 8 bits to 16 bits per sample. As of 2020, some smartphones have started using 30-bit color depth, such as the OnePlus ;8 Pro , Oppo Find X2 & Find X2 Pro, Sony Xperia 1 II , Xiaomi Mi 10 Ultra , Motorola Edge+ , ROG Phone 3 and Sharp Aquos Zero 2. Using 12 bits per color channel produces 36 bits, 68,719,476,736 colors. If an alpha channel of

384-418: A color component, the concept can be defined as bits per component , bits per channel , bits per color (all three abbreviated bpc), and also bits per pixel component , bits per color channel or bits per sample (bps). Modern standards tend to use bits per component, but historical lower-depth systems used bits per pixel more often. Color depth is only one aspect of color representation, expressing

448-412: A color cube in the palette for a direct-color system (and so all programs would use the same palette). Usually fewer levels of blue were provided than others, since the normal human eye is less sensitive to the blue component than to either red or green (two thirds of the eye's receptors process the longer wavelengths ). Popular sizes were: 4,096 colors, usually from a fully-programmable palette (though it

512-505: A contemporary laser printer) but color proved more popular. 4 colors, usually from a selection of fixed palettes. Gray-scale early NeXTstation , color Macintoshes, Atari ST medium resolution. 8 colors, almost always all combinations of full-intensity red, green, and blue. Many early home computers with TV displays, including the ZX Spectrum and BBC Micro . 16 colors, usually from a selection of fixed palettes. Used by IBM CGA (at

576-531: A limited 8-bit depth graphic display, it is necessary to load a given image's adaptive palette into the color hardware registers prior to loading the image surface itself into the frame buffer . To display different images with different adaptive palettes, they must be loaded one by one, as in a slideshow . Here are samples of four different indexed color images with color patches to show their respective (and largely incompatible) adaptive palettes: A single palette entry in an indexed color image can be designated as

640-464: A platform for selling TI DRAM and video palette chips as well as the GSP chips themselves. Despite the superiority of the technology in comparison to typical Super VGA cards of the era, the relatively high cost and emerging local bus graphics standards meant that IT distributors and PC manufacturers could not see a niche for these products at consumer level. The (limited) success of the graphics cards paved

704-455: A visually lossless low-latency algorithm based on predictive DPCM and YCoCg-R color space and allows increased resolutions and color depths and reduced power consumption." At WinHEC 2008, Microsoft announced that color depths of 30 bits and 48 bits would be supported in Windows 7 , along with the wide color gamut scRGB . High Efficiency Video Coding (HEVC or H.265) defines

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768-413: A yellow subpixel. However, formats and media that allow or make use of the extended color gamut are at present extremely rare. Because humans are overwhelmingly trichromats or dichromats one might suppose that adding a fourth "primary" color could provide no practical benefit. However humans can see a broader range of colors than a mixture of three colored lights can display. The deficit of colors

832-422: Is a stub . You can help Misplaced Pages by expanding it . Color depth Color depth or colour depth (see spelling differences ), also known as bit depth , is either the number of bits used to indicate the color of a single pixel , or the number of bits used for each color component of a single pixel. When referring to a pixel, the concept can be defined as bits per pixel (bpp). When referring to

896-414: Is also often used to refer to all color depths greater or equal to 24. Deep color consists of a billion or more colors. 2 is 1,073,741,824. Usually this is 10 bits each of red, green, and blue (10 bpc). If an alpha channel of the same size is added then each pixel takes 40 bits. Some earlier systems placed three 10-bit channels in a 32-bit word , with 2 bits unused (or used as

960-554: Is assigned 5 bits, plus one unused bit (or used for a mask channel or to switch to indexed color); this allows 32,768 colors to be represented. However, an alternate assignment which reassigns the unused bit to the G channel allows 65,536 colors to be represented, but without transparency. These color depths are sometimes used in small devices with a color display, such as mobile phones, and are sometimes considered sufficient to display photographic images. Occasionally 4 bits per color are used plus 4 bits for alpha, giving 4,096 colors. Among

1024-480: Is not being used to hold any translucency data and is set to zero. By contrast, PNG supports alpha channels in palette entries, enabling semi-transparency in paletted images. When dealing with truecolor images, some video mixing equipment can employ the RGB triplet (0,0,0) (no red, no green, no blue: the darkest shade of black, sometimes referred as superblack in this context) as the transparent color. At design time, it

1088-404: Is particularly noticeable in saturated shades of bluish green (shown as the left upper grey part of the horseshoe in the diagram) of RGB displays: Most humans can see more vivid blue-greens than any color video screen can display. Palette (computing) In computer graphics , a palette is the set of available colors from which an image can be made. In some systems, the palette is fixed by

1152-497: Is placed anywhere over the background image, and it is blended in such way that if the pixel color index is the transparent color, the background pixel is kept, otherwise it is replaced. This technique is used for pointers, in typical 2-D videogames for characters, bullets and so on (the sprites ), video titling and other image mixing applications. Some early computers, as Commodore 64 , MSX and Amiga supports sprites and/or full screen video overlay by hardware. In these cases,

1216-404: Is replaced by the so-called magic pink . The same way, typical desktop publishing software can assume pure white, RGB triplet (255,255,255) from photos and illustrations to be excluded in order to let the text paragraphs to invade the image's bounding box for irregular text arrangement around the image's subjects. 2-D painting programs , like Microsoft Paint and Deluxe Paint , can employ

1280-421: Is sometimes referred to as a uniform palette . The normal human eye has sensibility to the three primary colors in different degrees: the more to the green, the less to the blue. So RGB arrangements can take advantage of this by assigning more levels for the green component and fewer to the blue. A master palette built this way can be filled with up to 8R×8G×4B = 256 colors , but this does not leave space in

1344-527: Is used by virtually every computer and phone display and the vast majority of image storage formats . Almost all cases of 32 bits per pixel assigns 24 bits to the color, and the remaining 8 are the alpha channel or unused. 2 gives 16,777,216 color variations. The human eye can discriminate up to ten million colors, and since the gamut of a display is smaller than the range of human vision, this means this should cover that range with more detail than can be perceived. However, displays do not evenly distribute

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1408-773: The Nvidia Quadro graphics cards manufactured after 2006 support 30-bit deep color and Pascal or later GeForce and Titan cards when paired with the Studio Driver as do some models of the Radeon HD ;5900 series such as the HD ;5970. The ATI FireGL V7350 graphics card supports 40- and 64-bit pixels (30 and 48 bit color depth with an alpha channel). The DisplayPort specification also supports color depths greater than 24 bpp in version 1.3 through " VESA Display Stream Compression , which uses

1472-560: The Win32 API . The applicability of palettes in Highcolor and Truecolor display modes becomes questionable. These APIs deals with the so-called "system palette" and with many "logical palettes". The "system palette" is a copy in RAM of the color display's hardware registers, primarily a physical palette, and it is a unique, shared common resource of the system. At boot, it is loaded with

1536-488: The color gamut of a display, since it is no longer limited to the interior of a triangle formed by three primaries at its corners, e.g. the CIE 1931 color space . Recent technologies such as Texas Instruments 's BrilliantColor augment the typical red, green, and blue channels with up to three other primaries: cyan, magenta, and yellow. Cyan would be indicated by negative values in the red channel, magenta by negative values in

1600-529: The default system palette (mainly a "master palette" which works well enough with most programs). When a given application intends to output colorized graphics and/or images, it can set their own "logical palette", that is, its own private selection of colors (up to 256). It is supposed that every graphic element that the application tries to show on screen employs the colors of its logical palette. Every program can manage freely one or more logical palettes without further expected interference (in advance). Before

1664-436: The open standard image file format OpenEXR which supported 16-bit-per-channel half-precision floating-point numbers. At values near 1.0, half precision floating point values have only the precision of an 11-bit integer value, leading some graphics professionals to reject half-precision in situations where the extended dynamic range is not needed. Virtually all television displays and computer displays form images by varying

1728-437: The truecolor original one by using adaptive palettes (sometimes termed adaptative palettes ), in which the colors are selected or quantized through some algorithm directly from the original image (by picking the most frequent colors). This way, and with further dithering , the indexed color image can nearly match the original. But this creates a heavy dependence between the image pixels and its adaptive palette. Assuming

1792-664: The Main ;10 profile, which allows for 8 or 10 bits per sample with 4:2:0 chroma subsampling . The Main 10 profile was added at the October ;2012 HEVC meeting based on proposal JCTVC-K0109 which proposed that a 10-bit profile be added to HEVC for consumer applications. The proposal stated that this was to allow for improved video quality and to support the Rec. 2020 color space that will be used by UHDTV . The second version of HEVC has five profiles that allow for

1856-596: The PC clone market included Number Nine Visual Technology and Hercules . Number Nine Visual Technology graphics cards using Texas Instruments' TIGA co-processors were made from about 1986 to 1992, including the Pepper and GX series. Hercules manufactured cards such as the Graphics Station and Chrome lines which were marketed primarily toward users of Microsoft Windows . Desktop Computing AGA 1024 card

1920-444: The ability to use a different palette per sprites and tiles in order to increase the maximum number of simultaneously displayed colors, while minimizing use of then-expensive memory (and bandwidth). 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 8×8 pixels. The palette itself has a color depth (number of bits per entry). While

1984-443: The best VGA systems only offered an 18-bit (262,144 color) palette from which colors could be chosen, all color Macintosh video hardware offered a 24-bit (16 million color) palette. 24-bit palettes are nearly universal on any recent hardware or file format using them. If instead the color can be directly figured out from the pixel values, it is "direct color". Palettes were rarely used for depths greater than 12 bits per pixel, as

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2048-413: The bottom 2 bits of 8-bit data, but if 16 bits were used it would lose none of the 8-bit data). In addition, digital cameras are able to produce 10 or 12 bits per channel in their raw data; as 16 bits is the smallest addressable unit larger than that, using it would make it easier to manipulate the raw data. Some systems started using those bits for numbers outside the 0–1 range rather than for increasing

2112-400: The colors in human perception space, so humans can see the changes between some adjacent colors as color banding . Monochromatic images set all three channels to the same value, resulting in only 256 different colors; some software attempts to dither the gray level into the color channels to increase this, although in modern software this is more often used for subpixel rendering to increase

2176-479: The context of satellite images . With the relatively low color depth, the stored value is typically a number representing the index into a color map or palette (a form of vector quantization ). The colors available in the palette itself may be fixed by the hardware or modifiable by software. Modifiable palettes are sometimes referred to as pseudocolor palettes. Old graphics chips, particularly those used in home computers and video game consoles , often have

2240-537: The fact that many programs fail to handle this event, and their windows will become corrupt in this situation. An application can force the system palette to be loaded with specific colors (even in a specific order), "tricking" the system by telling it they are color entries intended for animation (quick color changes of the colors in the physical palette at specific entries). The system will then assume that those hardware palette entries no longer are free for its palette color management algorithm. The final result depends on

2304-769: The first hardware to use the standard were the Sharp X68000 and IBM's Extended Graphics Array (XGA). The term "high color" has recently been used to mean color depths greater than 24 bits. Almost all of the least expensive LCDs (such as typical twisted nematic types) provide 18-bit color (64×64×64 = 262,144 combinations) to achieve faster color transition times, and use either dithering or frame rate control to approximate 24-bit-per-pixel true color, or throw away 6 bits of color information entirely. More expensive LCDs (typically IPS ) can display 24-bit color depth or greater. 24 bits almost always use 8 bits each of R, G, and B (8 bpc). As of 2018, 24-bit color depth

2368-582: The fraction. The Cineon imaging system used 10-bit professional video displays with the video hardware adjusted so that a value of 95 was black and 685 was white. The amplified signal tended to reduce the lifetime of the CRT. More bits also encouraged the storage of light as linear values, where the number directly corresponds to the amount of light emitted. Linear levels makes calculation of computer graphics much easier. However, linear color results in disproportionately more samples near white and fewer near black, so

2432-414: The green channel, and yellow by negative values in the blue channel, validating the use of otherwise fictitious negative numbers in the color channels. Mitsubishi and Samsung (among others) use BrilliantColor in some of their TV sets to extend the range of displayable colors. The Sharp Aquos line of televisions has introduced Quattron technology, which augments the usual RGB pixel components with

2496-559: 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. 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. Images in which colors are indicated by references to

2560-404: The index number 0, but other may be chosen if the overlay is performed by software . At design time, the transparent color palette entry is assigned to an arbitrary (usually distinctive) color. In the example below, a typical arrow pointer for a pointing device is designed over an orange background, so here the orange areas denoted the transparent areas (left). At runtime , the overlapped image

2624-604: The late 1990s. An early example was the Radius ThunderPower card for the Macintosh, which included extensions for QuickDraw and Adobe Photoshop plugins to support editing 30-bit images. Some vendors call their 24-bit color depth with FRC panels 30-bit panels; however, true deep color displays have 10-bit or more color depth without FRC. The HDMI  1.3 specification defines a bit depth of 30 bits (as well as 36 and 48 bit depths). In that regard,

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2688-409: The least-used color in the system palette (generally, one used by another window in the background) and substitutes it with the new color. Due to there being limited room for colors in the system palette, the algorithm also tries to remap similar colors together and will always avoid creating redundant colors. The final result depends on how many applications are trying to show their colors on screen at

2752-600: The lowest resolution), EGA , and by the least common denominator VGA standard at higher resolution. Color Macintoshes, Atari ST low resolution, Commodore 64 , and Amstrad CPCs also supported 4-bit color. 32 colors from a programmable palette, used by the Original Amiga chipset . 64 colors. Used by the Master System , Enhanced Graphics Adapter, GIME for TRS-80 Color Computer 3, Pebble Time smartwatch (64 color e-paper display), and Parallax Propeller using

2816-454: The master palette (after dumping this into the hardware color registers), and writes the result in the video buffer. Here is a sample of a simple mosaic of the four image thumbnails using a master palette of 240 RGB arranged colors plus 16 additional intermediate shades of gray; all images are put together without a significant loss of color accuracy: When using indexed color techniques, real life images are represented with better fidelity to

2880-472: The memory consumed by the palette would exceed the necessary memory for direct color on every pixel. 2 colors, often black and white direct color. Sometimes 1 meant black and 0 meant white, the inverse of modern standards. Most of the first graphics displays were of this type, the X Window System was developed for such displays, and this was assumed for a 3M computer . In the late 1980s there were professional displays with resolutions up to 300 dpi (the same as

2944-406: The output is effectively made, the program must realize its logical palette: The system tries to match the "logical" colors with "physical" ones. If an intended color is already present in the system palette, the system internally maps the logical to the system palette indexes (because they rarely coincide). If the intended color is not present yet, the system applies an internal algorithm to discard

3008-482: The palette for reserved colors, color indices that the program could use for special purposes. It is more general to use only 6R×6G×6B = 216 (as in the Web colors case), 6R×8G×5B = 240 or 6R×7G×6B = 252 , which leaves room for some reserved colors. Then, when loading the mosaic of image thumbnails (or other heterogeneous images), the program simply maps every original indexed color pixel to its most approximated in

3072-439: The precision with which the amount of each primary can be expressed; the other aspect is how broad a range of colors can be expressed (the gamut ). The definition of both color precision and gamut is accomplished with a color encoding specification which assigns a digital code value to a location in a color space . The number of bits of resolved intensity in a color channel is also known as radiometric resolution , especially in

3136-453: The quality of 16-bit linear is about equal to 12-bit sRGB . Floating point numbers can represent linear light levels spacing the samples semi-logarithmically. Floating point representations also allow for drastically larger dynamic ranges as well as negative values. Most systems first supported 32-bit per channel single-precision , which far exceeded the accuracy required for most applications. In 1999, Industrial Light & Magic released

3200-422: The reference VGA circuit. 256 colors, usually from a fully-programmable palette: Most early color Unix workstations, Super VGA , color Macintosh , Atari TT , Amiga AGA chipset , Falcon030 , Acorn Archimedes . Both X and Windows provided elaborate systems to try to allow each program to select its own palette, often resulting in incorrect colors in any window other than the one with focus. Some systems placed

3264-422: The resolution. Numbers greater than 1 were for colors brighter than the display could show, as in high-dynamic-range imaging (HDRI). Negative numbers can increase the gamut to cover all possible colors, and for storing the results of filtering operations with negative filter coefficients. The Pixar Image Computer used 12 bits to store numbers in the range [-1.5, 2.5), with 2 bits for the integer portion and 10 for

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3328-454: The same size is added then there are 48 bits per pixel. Using 16 bits per color channel produces 48 bits, 281,474,976,710,656 colors. If an alpha channel of the same size is added then there are 64 bits per pixel. Image editing software such as Adobe Photoshop started using 16 bits per channel fairly early in order to reduce the quantization on intermediate results (i.e. if an operation is divided by 4 and then multiplied by 4, it would lose

3392-427: The same time in the hardware color registers. 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. 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. This kind of arrangement

3456-405: The same time. The foreground window is always favored, so background windows may behave in different ways: from become corrupted to quickly redraw themselves. When the system palette changes, the system triggers a specific event to inform every application. When received, a window can quickly redraw itself using a single Win32 API function. But this must be done explicitly in the program code; hence

3520-470: The space resolution on LCD screens where the colors have slightly different positions. The DVD-Video and Blu-ray Disc standards support a bit depth of 8 bits per color in YCbCr with 4:2:0 chroma subsampling . YCbCr can be losslessly converted to RGB. MacOS refers to 24-bit colour as "millions of colours". The term true colour is sometimes used to mean what this article is calling direct colour . It

3584-406: The strength of just three primary colors : red, green, and blue. For example, bright yellow is formed by roughly equal red and green contributions, with no blue contribution. For storing and manipulating images, alternative ways of expanding the traditional triangle exist: One can convert image coding to use fictitious primaries, that are not physically possible but that have the effect of extending

3648-412: The transparent palette entry number is defined by the hardware, and it used to be the number 0. Some indexed color image file formats as GIF natively support the designation of a given palette entry as transparent , freely selectable among any of the palette entries used for a given image. The BMP file format reserves space for Alpha channel values in its Color Table, however currently this space

3712-433: The triangle to enclose a much larger color gamut. An equivalent, simpler change is to allow negative numbers in color channels, so that the represented colors can extend out of the color triangle formed by the primaries. However these only extend the colors that can be represented in the image encoding; neither trick extends the gamut of colors that can actually be rendered on a display device. Supplementary colors can widen

3776-525: 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). Each possible color is assigned an index, which allows each color to be referenced using less information than needed to fully describe the color. 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

3840-485: The user designated background color as the transparent color when performing cut, copy, and paste operations. Although related (due to they are used for the same purposes), image bit masks and alpha channels are techniques which do not involve the use of palettes nor transparent color at all, but off-image added extra binary data layers. Microsoft Windows applications manage the palette of 4-bit or 8-bit indexed color display devices through specialized functions of

3904-429: The way for products based upon various derivatives and clones of IBM's 8514 architecture. Part of the effort to make graphics accelerators useful required TI to convince Microsoft that the internal interfaces to its Windows Operating System had to be adaptable instead of hard-coded. Indeed, all versions of Windows prior to Windows 3.0 were " hard-coded " to specific graphics hardware. This computer hardware article

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3968-457: The whole 24 bit color space, each being assigned an 8 bit index. 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. 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

4032-498: Was capable of emulating TIGA standards, besides IBM 8514. In the early 1990s, Texas Instruments France (which had marketing control for TIGA architecture and GSP chipsets in Europe) experimented with manufacturing and selling its own range of consumer oriented video cards based on TIGA and aimed at speeding up the user experience of Windows. These products were named TIGA Diamond (34020 based) and TIGA Star (34010 based), and provided

4096-469: Was often set to a 16×16×16 color cube). Some Silicon Graphics systems, Color NeXTstation systems, and Amiga systems in HAM mode have this color depth. RGBA4444, a related 16 bpp representation providing the color cube and 16 levels of transparency, is a common texture format in mobile graphics. In high-color systems, two bytes (16 bits) are stored for each pixel. Most often, each component (R, G, and B)

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