Halftone images using printed symbols modelling

Claim 3

A method of generating a halftone image (104) as recited in claim 1, wherein the model of the symbols printed by the printer (105) is a circle (175).

Claim 4

A method of generating a halftone image (104) as recited in claim 1, wherein the model of the symbols printed by the printer (105) is a probability profile (180).

Claim 5

A method of generating a halftone image (104) as recited in claim 1, wherein the model of the symbols printed by the printer (105) is a digitized representation of the printed symbol (450).

Claim 6

A method of generating a halftone image (104) as recited in claim 1, wherein the dither matrix (110) is constructed by the steps (200) of: generating (202) an intermediate pattern (300) having a plurality of elements, each element having eithera maximum ora minimum value, the values of the elements being dependent on the model (175, 180) of the symbols, those elements having the maximum value being distributed substantially uniformly within the pattern (300); and generating a plurality of other patterns, each pattern having a different number of elements of the maximum value than the intermediate pattern, and summing the intermediate pattern (300) and the plurality of other patterns to get the dither matrix.

Claim 7

A method of generating a halftone image as recited in claim 5, wherein the step of "generating a plurality of other patterns" further comprises the steps of: generating (204) a pattern of the dither matrix (110) with fewer elements having the maximum value than the intermediate pattern (300); and generating (206) a pattern of the dither matrix (110) with fewer elements having the minimum value than the intermediate pattern (300).

Claim 8

A method of generating a halftone image as recited in claim 5, wherein the step (202) of "generating an intermediate pattern" further comprises: using (425) a random pattern as the starting values for the intermediate pattern (300), the random pattern having elements of randomly distributed maximum and minimum values; copying (426) the intermediate pattern (300) into a dummy pattern; modifying (427) the values of the elements in the dummy pattern by the model (175, 180) of the symbols; filtering (428) the dummy pattern by the filter; identifying (430) from the filtered output the position having the element with the largest value as the maximum position, and the position having the element with the smallest value as the minimum position; exchanging (432) elements in the maximum and minimum position of the intermediate pattern (300); and repeating (434) from the step (426) of "copying the intermediate pattern" until the intermediate pattern (300) has reached an equilibrium state.

Claim 9

A method of generating a halftone image (104) as recited in claim 7, wherein the intermediate pattern (300) has reached the equilibrium state when the difference between the largest and the smallest value in the filtered output remains substantially constant with additional filtering.

Claim 10

A method of generating a halftone image (104) as recited in claim 6, wherein the step (204) of "generating a pattern of the dither matrix with fewer elements having the maximum values" further comprises: copying (502) the intermediate pattern (300) into a dummy pattern; modifying (504) the values of the elements in the dummy pattern by the model (175, 180) of the symbols; generating (506) a start sum from the values of the elements in the dummy pattern; filtering the dummy pattern by the filter; identifying from the filtered output the position having the element with the largest value as the maximum position; replacing the value of the element in the maximum position of the intermediate pattern (300) with the minimum value; copying the intermediate pattern (300) into the dummy pattern; modifying (510) the values of the elements in the dummy pattern by the model (175, 180) of the symbols; generating (512) an end sum from the values of the elements in the dummy pattern; repeating (514) from the "filtering" step until the difference between the start sum and end sum is less than or equal to a quantization number to generate one pattern of the dither matrix (110); setting (515) the start sum equal to the end sum; and repeating (516) from the "filtering" step until the end sum is less than or equal to the quantization number.

Claim 11

A method of generating a halftone image (104) as recited in claim 6, wherein the step (206) of "generating a pattern of the dither matrix with fewer elements having the minimum values" further comprises: copying (552) the intermediate pattern (300) into a dummy pattern; modifying (554) the values of the elements in the dummy pattern by the model (175, 180) of the symbols; generating (556) a start sum from the values of the elements in the dummy pattern; filtering the dummy pattern by the filter; identifying from the filtered output the position having the element with the smallest value as the minimum position; replacing the value of the element in the minimum position of the intermediate pattern (300) with the maximum value; copying the intermediate pattern into the dummy pattern; modifying (560) the values of the elements in the dummy pattern by the model (175, 180) of the symbols; generating (562) an end sum from the values of the elements in the dummy pattern; repeating (564) from the "filtering" step until the difference between the start sum and end sum is less than or equal to a quantization number to generate one pattern of the dither matrix (110); setting (565) the start sum as the end sum; and repeating (566) from the "filtering" step until the end sum is more than or equal to ((the total number of patterns of the dither matrix - 1) * the quantization number).