Patent ID: 7809201

Claim:
An image processing apparatus that converts multilevel input image data into multilevel output image data having fewer levels than the multilevel input image data and used in an image output device, comprising: a determining device that determines an output level value of a subject pixel in the output image data based on a comparison between an input level value of the subject pixel in the input image data and a threshold value corresponding to the subject pixel in a dither matrix; a mode setting device that adjusts the image output device to operate in one of a plurality of image output modes each of which outputs output image data at a different resolution; a storage device that stores a plurality of dither matrices of varying sizes according to representable levels in association with the plurality of image output modes; and a dither matrix selecting device that selects a dither matrix of the plurality of dither matrices stored in the storage device corresponding to the one of the plurality of image output modes set by the mode setting device as a dither matrix directly used by the determining device, wherein: when a predetermined image output mode is set by the mode setting device, the dither matrix selecting device selects a dither matrix that has a larger number of levels than a number of levels of the input image data, and the predetermined image output mode is an image output mode for outputting output image data having a highest resolution.