Computer graphicsComputer graphics deals with generating s and art with the aid of computers. Today, computer graphics is a core technology in digital photography, film, video games, digital art, cell phone and computer displays, and many specialized applications. A great deal of specialized hardware and software has been developed, with the displays of most devices being driven by computer graphics hardware. It is a vast and recently developed area of computer science. The phrase was coined in 1960 by computer graphics researchers Verne Hudson and William Fetter of Boeing.
Web colorsWeb colors are colors used in displaying web pages on the World Wide Web, as well as the methods for describing and specifying those colors. Colors may be specified as an RGB triplet or in hexadecimal format (a hex triplet) or according to their common English names in some cases. A color tool or other graphics software is often used to generate color values. In some uses, hexadecimal color codes are specified with notation using a leading number sign (#).
BitmapIn computing, a bitmap is a mapping from some domain (for example, a range of integers) to bits. It is also called a bit array or bitmap index. As a noun, the term "bitmap" is very often used to refer to a particular bitmapping application: the pix-map, which refers to a map of pixels, where each one may store more than two colors, thus using more than one bit per pixel. In such a case, the domain in question is the array of pixels which constitute a digital graphic output device (a screen or monitor).
DitherDither is an intentionally applied form of used to randomize quantization error, preventing large-scale patterns such as color banding in images. Dither is routinely used in processing of both digital audio and video data, and is often one of the last stages of mastering audio to a CD. A common use of dither is converting a grayscale image to , such that the density of black dots in the new image approximates the average gray level in the original. ...[O]ne of the earliest [applications] of dither came in World War II.
Indexed colorIn computing, indexed color is a technique to manage s' colors in a limited fashion, in order to save computer memory and file storage, while speeding up display refresh and file transfers. It is a form of vector quantization compression. When an image is encoded in this way, color information is not directly carried by the image pixel data, but is stored in a separate piece of data called a color lookup table (CLUT) or palette: an array of color specifications. Every element in the array represents a color, indexed by its position within the array.
Color quantizationIn computer graphics, color quantization or color image quantization is applied to color spaces; it is a process that reduces the number of distinct colors used in an , usually with the intention that the new image should be as visually similar as possible to the original image. Computer algorithms to perform color quantization on bitmaps have been studied since the 1970s. Color quantization is critical for displaying images with many colors on devices that can only display a limited number of colors, usually due to memory limitations, and enables efficient compression of certain types of images.
Gamma correctionGamma correction or gamma is a nonlinear operation used to encode and decode luminance or tristimulus values in video or systems. Gamma correction is, in the simplest cases, defined by the following power-law expression: where the non-negative real input value is raised to the power and multiplied by the constant A to get the output value . In the common case of A = 1, inputs and outputs are typically in the range 0–1.
Transparency (graphic)Transparency in computer graphics is possible in a number of . The term "transparency" is used in various ways by different people, but at its simplest there is "full transparency" i.e. something that is completely invisible. Only part of a graphic should be fully transparent, or there would be nothing to see. More complex is "partial transparency" or "translucency" where the effect is achieved that a graphic is partially transparent in the same way as colored glass.
Sprite (computer graphics)In computer graphics, a sprite is a two-dimensional bitmap that is integrated into a larger scene, most often in a 2D video game. Originally, the term sprite referred to fixed-sized objects composited together, by hardware, with a background. Use of the term has since become more general. Systems with hardware sprites include arcade video games of the 1970s and 1980s; game consoles including as the Atari VCS (1977), ColecoVision (1982), Nintendo Entertainment System (1983), and Sega Genesis (1988); and home computers such as the TI-99/4 (1979), Atari 8-bit family (1979), Commodore 64 (1982), MSX (1983), Amiga (1985), and X68000 (1987).
Alpha compositingIn computer graphics, alpha compositing or alpha blending is the process of combining one image with a background to create the appearance of partial or full transparency. It is often useful to render picture elements (pixels) in separate passes or layers and then combine the resulting 2D images into a single, final image called the composite. Compositing is used extensively in film when combining elements with live footage. Alpha blending is also used in 2D computer graphics to put rasterized foreground elements over a background.
