Patent ID: 7542170

Claim:
A method for enhancing the print quality of halftone images, the method comprising: detecting an edge characteristic and an edge direction of a document to be printed; performing halftone processing to the document by means of error diffusion; and separately processing input image pixels both with and without an edge characteristic in the document based at least in part upon the detected edge characteristic and the edge direction, wherein processing causes the pixels with an edge characteristic to have a concentrated distribution and the pixels without an edge characteristic to have a divergent distribution, wherein a conditioning quantizer determines whether the input image pixels are to be printed based at least in part upon whether an input image pixel is larger than a present gray scale verifying threshold and whether a second pixel is larger than a second threshold, and wherein the condition quantizer determines whether the input image pixels are to be printed based on whether an edge characteristic value of the input image pixels is larger than a preset edge characteristic threshold.