Patent ID: 7110141

Claim:
An image processing apparatus employing an error distribution process to convert an image represented with multiple values into an image provided in binary representation, comprising: an input block subtracting from data of a target pixel successively input an error from a neighboring pixel; a thresholding block thresholding and outputting said data of said target pixel subjected to a subtraction in said input block; an error calculation block subtracting from a thresholded value output from said thresholding block a value corresponding to said data of said target pixel having been subjected to said subtraction in said input block and not yet thresholded, to obtain an error; an error operation block multiplying an error obtained from said error calculation block by a distribution weighting coefficient to calculate an error to be distributed to a neighboring pixel before said neighboring pixel is processed, said distribution weighting coefficient simply decreasing as a distance from said target pixel increases; and a threshold operation block adding to a threshold value used in said thresholding block a second image pattern related to a first image pattern introduced into an output image as a result of an image processing provided by said input block, said thresholding block, said error calculation block and said error operation block; wherein said second image pattern has a predetermined angle, with an absolute value greater than zero, relative to said first image pattern.