Correlating cyan and magenta planes for error diffusion halftoning

Claim 2

The method of Claim 1, wherein said steps of performing error diffusion and correlating printing of dots are also performed for at least a third color ink, said method further comprising the step of: prioritizing said first color ink, said second color ink, and said third color ink when determining a color ink dot to print.

Claim 3

The method of Claim 2 further comprising the step of printing a dot of said first color ink, said second color ink, or said third color ink based on said steps of performing error diffusion, correlating printing of dots, and prioritizing.

Claim 4

The method of Claim 1, 2, or 3 wherein said steps of performing error diffusion and correlating printing comprise: (a) determining (34) a tone to be reproduced using at least two colors, including said first color and said second color; (b) setting (48) a threshold value; (c) identifying (50) an intensity of said first color component in said tone to be reproduced; (d) identifying (51) an intensity of said second color in said tone to be reproduced; (e) accumulating (68) a first error value signifying an error in intensity between printed dots of said first color (6) and a desired intensity of said first color; (f) accumulating (68) a second error value signifying an error in intensity between printed dots of said second color (4) and a desired intensity of said second color; (g) summing (74) said desired intensity of said first color, said first error value, said desired intensity of said second color, and said second error value to generate a sum value; (h) determining (76) whether said sum value is greater than said threshold value and, if so, determining that either a dot of said first color or a dot of said second color should be printed; and (i) determining (78) whether said desired intensity of said first color plus said first error value is greater than said desired intensity of said second color plus said second error value and, if so, printing (82) said dot of said first color or, if not, printing (80) said dot of said second color.

Claim 5

The method of Claim 4 wherein said first color is cyan (6) and said second color is magenta (4).

Claim 6

The method of Claim 4 wherein steps h and i are only conducted if it is determined that said sum value in step g equates to less than a solid fill (56) of dots of said first color and/or said second color.

Claim 7

The method of Claim 6 wherein, if it is determined in step g that said sum value is equal to or greater than said solid fill of dots of said first color and/or said second color, then using an error diffusion process (58, 62) to print said dots (6) of said first color or said dots (4) of said second color which does not combine intensities and error values of said first color and said second color.

Claim 8

The method of Claim 4 further comprising the step of printing dots of said first color (6) and said second color (4) between steps d and e.

Claim 9

The method of Claim 8 wherein said method forces said dots (6) of said first color and said dots (4) of said second color to be separated from one another so as not to be adjacent.

Claim 10

A printing system including a printer (10, 24) and a computer (22), said printing system performing a halftone method which correlates printing of dots from multiple color planes to reduce a likelihood that printed dots of any color will be directly adjacent one another, said method performed by said system comprising: (a) determining (34) a tone to be reproduced using at least two colors, including said first color and said second color; (b) setting (48) a threshold value; (c) identifying (50) an intensity of said first color component in said tone to be reproduced; (d) identifying (51) an intensity of said second color in said tone to be reproduced; (e) accumulating (68) a first error value signifying an error in intensity between printed dots of said first color (6) and a desired intensity of said first color; (f) accumulating (68) a second error value signifying an error in intensity between printed dots of said second color (4) and a desired intensity of said second color; (g) summing (74) said desired intensity of said first color, said first error value, said desired intensity of said second color, and said second error value to generate a sum value; (h) determining (76) whether said sum value is greater than said threshold value and, if so, determining that either a dot of said first color or a dot of said second color should be printed; and (i) determining (78) whether said desired intensity of said first color plus said first error value is greater than said desired intensity of said second color plus said second error value and, if so, printing (82) said dot of said first color or, if not, printing (80) said dot of said second color.