two-state picture

The picture in which each pixel has only two possible values or gray scale states, for example, the picture of an image processing system with the value of “0” (black) or “1” (white) only.; 每一象素只有两种可能的数值或灰级状态的图形，例如图象处理系统中只含有“0”(黑)或“1”(白)的图形。