Term for converting to black&white

Is there a single word to denote reducing the color palette of an image to two colors: black and white? For instance, navy becomes black and beige turns into white.

I know there is desaturate, but it's too broad, can mean even a slight reduction in color.


The proper term for converting an image to black and white is binarize. The process of doing so is called binarization.

From Wiktionary:

binarize (third-person singular simple present binarizes, present participle binarizing, simple past and past participle binarized)

  1. (mathematics) To represent in binary
  2. To convert (an image) to only black and white.

An example usage would be: "The first step is to binarize the image by applying a threshold."


This question might be better asked at GD.SE but there is posterize:

posterize verb
[with object]
print or display (a photograph or other image) using only a small number of different tones:
   posterize the image and view the result

[ODO]

The term is derived from letterpress printing of posters, where only a limited number of solid colours were easily used.

Original and posterized images (using Paint Shop Pro's posterize function):

Queen Elizabeth II Conference Centre, LondonPosterized image


I agree with most of the suggestions above and will offer a few more:

  • Adopt the terminology "convert [source] to destination," as insisting on making everything a verb just makes most of the verbs very clumsy
  • threshold could be a synonym for posterizing to monochrome
  • halftone to 1-bit monochrome would cover another example of output in only one colorant (trading off spatial resolution for pixel depth)
    • but then you may want to state what kind of halftone (clustered dot screens with frequency and angle, or stochastic screens, or hybrids)