Patent ID: 7164503
Filing Date: 2007-01-16
Classification: H04N

Abstract:
1. An image-processing apparatus that determines dot on-off state for each pixel by taking into account a tone value of the pixel, and converts image data expressed by the tone value of each pixel into a specific expression format based on the dot on-off state, said image-processing apparatus comprising: a block formation unit that combines a specific number of adjacent pixels, out of the pixels forming the image, into blocks, and identifies the block which includes the pixel for which the dot on-off state is to be formed as a target block; a processing condition determination unit that detects the tone value of the each pixel included in the target block, and determines whether or not the target block satisfies a specific processing condition based on the detected magnitude of the tone values of respective pixels; a first image data conversion unit that converts the image data of each pixel included in the target block into the specific expression format based on the dot on-off state, in block units, when the processing condition determination unit determines that the target block satisfies the specific processing condition; a second image data conversion unit that converts the image data, with respect to each pixel included in the target block, into the specific expression format, when the processing condition determination unit determines that the target block does not satisfy the specific processing condition; and an error diffusion unit that diffuses tone errors, which arise due to the image data conversion, among unconverted pixels located peripherally of the converted pixel.