A binary image is a digital image that has only two possible values for each pixel, it can be black with value 0 and white of value 1 or 255.
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 image processing as masks or as the result of certain operations such as segmentation, thresholding, and dithering.
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.