Data Bases • Custom Term Papers • Free Term Papers • Free Research Papers • Free Essays • Free Book Reports • Plagiarism? Links • Top 100 Term Paper Sites • Top 25 Essay Sites • Top 50 Essay Sites • Search 97,000 Papers @ DirectEssays.com • Search 101,000 Papers @ ExampleEssays.com • Search 90,000 Papers @ MegaEssays.com Free Essays • Term Paper Sites • Chuck III's Free Essays • Free College Essays • TermPaperSites.com • My Term Papers • Get Free Essays • Essay World • Planet Papers	Search Lots of Essays Back to Subjects - Technology VGA VGA Video or graphics circuitry, usually fitted to a card but sometimes found on the motherboard itself, is responsible for creating the picture displayed by a monitor. On early text-based PCs this was a fairly mundane task. However, the advent of graphical operating systems dramatically increased the amount of information needing to be displayed to levels where it was impractical for it to be handled by the main processor. The solution was to off-load the handling of all screen activity to a more intelligent generation of graphics card. As the importance of multimedia and then 3D graphics has increased, the role of the graphics card has become ever more important and it has evolved into a highly efficient processing engine which can really be viewed as a highly specialised co-processor. By the late 1990s the rate of development in the graphics chip arena had reached levels unsurpassed in any other area of PC technology, with the major manufacturers such as 3dfx, ATI, Matrox, nVidia and S3 working to a barely believable six-month product life cycle! One of the consequences of this has been the consolidation of major chip vendors and graphics card manufacturers. Chip maker 3dfx started the trend in 1998 with the its acquisition of board manufacturer STB systems. This gave 3dfx a more direct route to market with retail product and the ability to manufacture and distribute boards that bearing its own branding. Rival S3 followed suit in the summer of 1999 by buying Diamond Mulitmedia, thereby acquiring its graphics and sound card, modem and MP3 technologies. A matter of weeks later, 16-year veteran Number Nine announced its abandonment of the chip development side of its business in favour of board manufacturing. The consequence of all this manoeuvring was to leave nVidia as the last of the major graphics chip vendors without its own manufacturing facility - and the inevitable speculation of a tie-up with close partner, Creative Labs. Whilst there'd been no developments on this front by mid-2000, nVidia's position in had been significantly strengthened by S3's sale of its graphics business to VIA Technologies in April of that year. The move - which S3 portrayed as an important step in the transformation of the company from a graphics focused semiconductor supplier to a more broadly based Internet appliance company - left nVidia as sole remaining big player in the graphics chip business. Resolution is a term often used interchangeably with addressability, but it more properly refers to the sharpness, or detail, of the visual image. It is primarily a function of the monitor and is determined by the beam size and dot pitch (sometimes referred to as 'line pitch'). An image is created when a beam of electrons strikes phosphors which coat the base of the monitor’s ‘screen’. A group comprising one red, one green and one blue phosphor is known as a pixel. A pixel represents the smallest piece of the screen that can be controlled individually, and each pixel can be set to a different colour and intensity. A complete screen image is composed of thousands of pixels and the screen's resolution - specified in terms of a row by column figure - is the maximum number of displayable pixels. The higher the resolution, the more pixels that can be displayed and therefore the more information the screen can display at any given time. Resolutions generally fall into predefined sets and the table below shows the series of video standards since CGA, the first to support colour/graphics capability All SVGA standards support the display of 16 million colours, but the number of colours that can be displayed simultaneously is limited by the amount of video memory installed in a system. The greater number of colours, or the higher the resolution or, the more video memory will be required. However, since it is a shared resource reducing one will allow an increase in the other. Each pixel of a screen image is displayed using a combination of three different colour signals: red, green and blue. The precise appearance of each pixel is controlled by the intensity of these three beams of light and the amount of information that is stored about a pixel determines its colour depth. The more bits that are used per pixel ('bit depth'), the finer the colour detail of the image. The table below shows the colour depths in current use: For a display to fool the eye into seeing full colour, 256 shades of red, green and blue are required; that is 8 bits for each of the three primary colours, hence 24 bits in total. However, some graphics cards actually require 32 bits for each pixel to display true colour, due to the way in which they use the video memory - the extra 8 bits generally being used for an alpha channel (transparencies). High colour uses two bytes of information to store the intensity values for the three colours, using 5 bits for blue, 5 bits for red and 6 bits for green. The resulting 32 different intensities for blue and red and 64 different intensities for green results in a very slight loss of visible image quality, but with the advantages of a lower video memory requirement and faster performance. The 256-colour mode uses a level of indirection by introducing the concept of a ‘palette’ of colours, selectable from the entire range of 16.7 million colours. Each colour in the 256-colour palette is defined using the standard 3-byte colour definition used in true colour: 256 possible intensities for each of red, blue and green. Any given image can then use any colour from its associated palette. The palette approach is an excellent compromise solution allowing for far greater precision in an image than would be possible by using the 8 bits available by, for example, assigning each pixel a 2-bit value for blue and 3-bit values each for green and red. Because of its relatively low demands on video memory the 256-colour mode is a widely used standard, especially in PCs used primarily for business applications. Dithering substitutes combinations of colours that a graphics card is able to generate for colours that it cannot produce. For example, if a graphics subsystem is capable of handling 256 colours, and an image that uses 65,000 colours is displayed, colours that are not available will be substituted by colours created from combinations of colours that are available. The colour quality of a dithered image is inferior to a non-dithered image. Dithering also refers to a technique that uses two colours to create the appearance of a third, giving a smoother appearance to otherwise abrupt transitions. In other words, it is also a method of using patterns to simulate gradations of grey or colour shades, or of anti-aliasing. Bibliography: Word Count: 1164
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