| 摘要 |
An image processing apparatus 30, which can solve the problems of delay in dot generation in beginning portions of areas of low or high density and tailing after finishing areas of low or high density and carry out speedy binary coding image processing without accompanying side effects of quality depletion and without the need to utilize a complicated processing circuit: includes error correction unit 34 which corrects multigradation image data 200 and outputs it, threshold error setting unit which sets a binary coding threshold value based on the gradation value of said target pixel multigradation image data 200 and binary coding unit 36 which, based on the set threshold value, converts the previously mentioned corrected pixel data into the previously mentioned bigradation image data and outputs it; the gradation value of the previously mentioned target pixel multigradation image data being data, the median value of the previously mentioned first gradation value and second gradation value being m and the previously mentioned threshold value being slsh, the previously mentioned threshold setting unit 36, when the gradation value of the previously mentioned target pixel multigradation image data is in the neighborhood of the previously mentioned first and second gradation values, the binary coding threshold value is set within the tolerance range shown in the following equations:when data<m, data</=slsh</=(m+data)/2,when data>m, (m+data)/2</=slsh</=data.
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