Black And White Photography

Most computers had monochrome (black-and-white, black and green, or black and amber) screens until the late 1980s; however, some home computers could be connected to television screens to eliminate the extra cost of a monitor. These took advantage of NTSC or PAL encoding to offer a range of colors from as low as 4 (IBM CGA) to 128 (Atari 800) to 4096 (Commodore Amiga). Early videogame consoles such as the Atari Video Computer System/VCS/2600 supported both black-and-white and color modes via a switch, as did some of the early home computers; this was to accommodate black-and-white TV sets which would display a color signal poorly. (Typically a different shading scheme would be used for the display in the black-and-white mode.)
In computing terminology, black-and-white is sometimes used to refer to a binary image consisting solely of pure black pixels and pure white pixels; what would normally be called a black-and-white image, that is, an image containing shades of gray, is referred to in this context as grayscale.