Patent ID: 6840599

Claim:
A method for processing an image in a printer capable of printing a two-color image, comprises the steps of: setting a primary color and a secondary color as printable colors in the printer; receiving an original image; and converting the original image into the primary, secondary, or white color associated with a smallest color difference value on a pixel-by-pixel basis, calculating a first color difference value ΔCol 1 between the corresponding pixel color of the original image and the primary color according to the equation ΔCol 1 =|R 0 −R 1 |+|G 0 −G 1 |+|B 0 −B 1 |−Vcb, calculating a second color difference value ΔCol 2 between the corresponding pixel color of the original image and the secondary color according to the equation ΔCol 2 =|R 2 −R 0 |+|G 2 −G 0 |+|B 2 −B 1 |−Vcs, calculating a third color difference value ΔCol 3 between the corresponding pixel color of the original image and the white color according to the equation ΔCol 3 =|255−R 0 |+|255−G 0 |+|255−B 0 |, and converting the corresponding pixel color into a conversion color associated with the smallest color difference value of the calculated color difference values ΔCol 1 , ΔCol 2 and ΔCol 3 , wherein R 0 , G 0 and B 0 are RGB values of the corresponding pixel color of the original image, R 1 , G 1 and B 1 are RGB values of the primary color, R 2 , G 2 and B 2 are RGB values of the secondary color, values of 255 are RGB values of the white color, Vcb is a weight value for the primary color, Vcs is a weight value for the secondary color, and the weight values Vcb and Vcs are arbitrarily set.