| 摘要 |
PROBLEM TO BE SOLVED: To allow preventing a generation of undesirable isolated dots in a low density portion and easily providing high quality output image data in image processing that employs an error diffusion method. SOLUTION: When binarizing a pixel of image data (2) represented by multi- valued gradation value or converting it to a predetermined plurality of values with a predetermined threshold as a criterion, an error is found between a value acquired after conversion of a pixel to be converted to a plurality of values and an original value, and the error found is distributed to other pixel which is yet processed. In this processing, an appropriate low density value is previously set, and when a density value of the target pixel of scan line is 0%, a density value of the target value is changed to the previously set density value, thus error diffusion processing being performed based on the changed density value. Furthermore, when an output result of the target value is dot on, the output result is changed to dot off.
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