Patent ID: 7027088

Claim:
A monotone conversion apparatus for converting color picture data into monotone picture data characterized in that it is provided with a picture acquisition unit for expressing a picture in picture elements in a dot matrix form and acquiring color picture data representing each picture element in gradation of prescribed element colors into which an original color is separated; a luminance distribution totaling unit for totaling the luminance equivalent of each picture element on the basis of these picture data; a luminance correspondence setting unit for setting a correspondence relationship for collective accomplishment of conversion so that, while converting the pertinent luminance distribution on the basis of output of the luminance distribution totaling unit, relative proportions among element colors be adjusted to prescribed values correspondingly to luminance values after luminance conversion; and a picture data conversion unit for generating monotone picture data in which the luminance of each picture element in said picture data is converted on the basis of this set correspondence relationship.