Patent ID: 8064689

Claim:
An image processing system comprising: a processor that executes a predetermined conversion process on input image data represented by pixels of M grayscales (M≧3), to convert the input image data into output image data represented by sub-pixels of two grayscales and having a size smaller than the pixel; and an output unit that outputs the output image data obtained from the processor, wherein the conversion process includes: a process to determine a filling pattern of a group of sub-pixels of the output image data corresponding to a pixel of interest of the input image data according to a corrected grayscale value obtained by adding a predetermined correction value to a grayscale value of the pixel of interest; and a process to calculate, as an error of the pixel of interest, an error between the corrected grayscale value and a grayscale value represented by the filling pattern, the filling pattern includes at least a core pattern in which a predetermined number of a plurality of sub-pixels are filled and which forms a core of a dot and a growth pattern in which a number of sub-pixels are filled, the number corresponding to the corrected grayscale value, and which grows an adjacent dot, the correction value is a value including a diffused error obtained by weighting an error of a peripheral pixel of the pixel of interest by an error diffusion coefficient, and at least a part of the diffused error obtained by weighting an error of a pixel, among the peripheral pixels, determined as the core pattern by the error diffusion coefficient is not included in the correction value and is allotted to proximate pixels of the pixel of interest including the pixel of interest.