By the end of the 20th cent. digital imaging and processing and computer-based techniques had made it possible to manipulate images in many ways, creating revolutionary changes in photography. Digital technology allowed for a fundamental change in the nature of photographic technique. Instead of light passing through a lens and striking emulsion on film, digital photography uses sensors and color filters. In one technique three filters are arranged in a mosaic pattern on top of the photosensitive layer. Each filter allows only one color (red, green, or blue) to pass through to the pixel beneath it. In the other technique, three separate photosensitive layers are embedded in silicon. Since silicon absorbs different colors at different depths, each layer allows a different color to pass through. When stacked together, a full color pixel results. In both techniques the photosensitive material converts images into a series of numbers that are then translated back into tonal values and printed. Using computers, various numbers can easily be changed, thus altering colors, rearranging pictorial elements, or combining photographs with other kinds of images. Some digital cameras record directly onto computer disks or into a computer, where the images can be manipulated at will.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.