Patent ID: 6157462
Filing Date: 2000-12-05
Classification: H04N

Abstract:
A method of printing a digital color image comprising:receiving input pixel data at a first depth in terms of ""c"" bits per pixel, wherein `c` is an integer, for at least three color separations of a digital color image;deriving pixel data at the first depth of `c` bits per pixel for a fourth separation of the digital color image based upon the pixel data of the three color separations;performing an error diffusion operation on the pixel data of the fourth separation to redefine the pixel of the fourth separation data at a second depth of `d` bits per pixel, where `d` is an integer and `d`<`c`;for each pixel of each of the three color separations, subtracting correspondingly located redefined pixel data of the fourth separation therefrom, respectively;after said such subtracting performing an error diffusion operation on the pixel data of each of the three color separations to redefine the pixel data of each pixel of each separation in terms of `d` bits per pixel;outputting the pixel data in terms of `d` bits per pixel for each of the three color separations and the fourth separation to an output device.