Patent ID: 8482591

Claim:
An apparatus comprising: a photosensitive member on which a latent image is formed; a plurality of light-emitting sources configured to irradiate different positions on the photosensitive member in a sub scanning direction in which the photosensitive member is rotated, the photosensitive member being scanned with light beams emitted from the light emitting sources in a main scanning direction; a developing unit configured to develop the latent image formed on the photosensitive member using a toner; a processing unit configured to perform halftone processing on image data using a dither matrix; and a drive unit configured to cause the plurality of light-emitting sources to emit light based on the processed image data, wherein, where a number of light-emitting sources is B and a number of pixels of the dither matrix in the sub scanning direction is M, the number M is not divisible by the number B, the number M is an odd number wherein threshold values of the dither matrix is line symmetric relative to a center in the sub scanning direction, and wherein the processing unit compares a value of a target pixel with one of the threshold values of the dither matrix, the one of the threshold values being selected from the threshold values based on a position of the target pixel in the main scanning direction and a position of the target pixel in the sub scanning direction.