Patent ID: 7710604

Claim:
A method of scaling a halftone image using error diffusion, the method comprising: identifying a first matrix of n×m pels in the halftone image; calculating an average intensity of the first matrix of pels; generating a second matrix of (n+1)×m pels from the first matrix of pels by inserting a line of pels in the first matrix of pels; generating a scaled output matrix of (n+1)×m pels from the second matrix of pels by assigning new pel values to each pel in the line of pels using an error diffusion process, wherein the average intensity of the scaled output matrix of pels is substantially unchanged from the average intensity of the first matrix of pels; generating a (n+1)×m shift matrix based on the second matrix and including at least one shift indicator defining an exchange between a pel and its neighboring pel, wherein a probability of occurrence of the at least one shift indicator in a position of the (n+1)×m shift matrix is proportional to a distance between the position and the line of pels in the second matrix; exchanging at least one pel in the scaled output matrix with its neighboring pel based on the shift matrix; and performing the previous steps for each unidentified matrix of n×m pels in the halftone image to generate a scaled output of the halftone image.