A binary image is a digital image that has only two possible values for each pixel.

Binary images are also called bi-level or two-level. (The names black-and-white, B&W, monochrome or monochromatic are often used for this concept, but may also designate any images that have only one sample per pixel, such as grayscale images.)

Binary images often arise in digital image processing as masks or as the result of certain operations such as segmentation, thresholding , and dithering. Some input/output devices, such as laser printers, fax machines, and bilevel computer displays, can only handle bilevel images.

A binary image is usually stored in memory as a bitmap, a packed array of bits.

Binary images can be interpreted as subsets of the two-dimensional integer lattice Z²; the field of morphological image processing was largely inspired by this view.

A binary image is also a compiled version of source code in Linux and Unices