transitive and intransitive. Photography. To tone (a photographic print) too much; to give too deep a tone to (a photographic print). rare.

To alter or modify the tone or general colouring of; to give the desired tone to (also const. down: cf sense 6b); spec. (a) To cover (a painting)…

transitive. To print (a photograph or other image) so that there is only a small number of different tones. Also occasionally intransitive.

transitive. To convert (a set of data, an image, etc.) to a binary form by reference to a threshold value; esp. to reproduce (an image) in two…