Patent ID: 8488194

Claim:
An image processing controller for performing screen processing for tone reduction of input image data, which has a tone value in N 1 tones (where N 1 is an integer that is greater than or equal to four) for each pixel, from the N 1 tones into N 2 tones (where N 2 is an integer that is greater than or equal to three but less than N 1 ) and generating output image data that is to be supplied to a printing unit, the printing unit being configured to be able to form an output image with the use of a recording material in accordance with the output image data, the output image data having N 3 tones greater than the N 2 tones of intermediate image data (N 3 is an integer that is greater than N 2 ), the intermediate image data being generated as a result of the screen processing performed on the input image data, the image processing controller comprising: a correspondence prescribing section that has a recording-material-saving correspondence that is used in a recording material saving mode for forming the output image while saving the recording material, the recording-material-saving correspondence prescribing correspondence between tone values of the intermediate image data having the N 2 tones and tone values of the output image data having the N 3 tones; and a recording-material-saving image processing section that performs the screen processing on the input image data having the N 1 tones to generate the intermediate image data having the N 2 tones, converts the intermediate image data having the N 2 tones into the output image data having the N 3 tones according to the recording-material-saving correspondence, and then supplies the output image data to the printing unit.