Blackwell Reference Online

Extract

Two distinct processes can give rise to digital images. On the one hand, they can be created entirely by computer, as →  animations or as single computer-generated images. On the other hand, they can be produced photographically, through digital cameras and camcorders, or through the digital scanning of photographs originally recorded on celluloid (→  Photography ). When a real visual scene is photographed digitally, the scene's pattern of light and color is translated into a rectangular grid of pictorial elements, known as pixels. Variations in brightness or color from one pixel to another are recorded in terms of discrete, fixed units – hence, “digitally” – instead of the continuous gradations employed by analog media. These properties of digital photographs, which are also characteristic of wholly computer-generated images, have substantial technological consequences. Digital images can be copied repeatedly with no significant loss of information between one generation and the next. Likewise, they can be transmitted without significant loss across computer networks. Perhaps most notably, from a communications perspective, digital images that started out as photographs can be manipulated and altered by computer. Because of the dominant position of Adobe Photoshop in the market for photo-manipulation software, the term “photoshop” has now entered the dictionary as a synonym for ... log in or subscribe to read full text