Binary image

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A photograph of a Neighborhood Watch sign in black and white (binary)
A photograph of a Neighborhood Watch sign in black and white (binary)

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.) In Photoshop parlance, a binary image is the same as an image in "Bitmap" mode.


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.

The interpretation of the pixel's binary value is also device-dependent. Some systems interprets the bit value of 0 as black and 1 as white, while others reversed the meaning of the values. These are known as vanilla and chocolate flavours in the TWAIN standard PC interface for scanners and digital cameras.

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 Unixes.

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