Patent Document ID: 20020181023
Application ID: 09870537
Patent Status: 0

Claim One:
1. A method of generating a halftone image from an input digital image, said digital image represented by a multiplicity of pixels, each pixel having a given value, said values being stored in a memory, said method comprising the steps of: (A) filtering the input digital image, said filtering having as output a filtered value at each pixel; (B) obtaining the difference between the value at the pixel and the filtered value at the pixel, said difference being a threshold input; (C) generating the output state for the pixel depending upon the relationship of the value of said threshold input relative to a threshold; (D) producing an error value, said error value being indicative of the deviation of said threshold input from the output state; (E) multiplying said error value by a coefficient, the result of said multiplication being stored; (F) combining the stored value with the difference between the next pixel value and the next filtered value to produce a new threshold input; (G) repeating steps (C) through (F) for each pixel in the digital image thereby producing a halftone image; and varying the threshold according to properties of the digital image; and selectively changing the coefficient in step (E) according to the local properties of the digital image.