Image processing apparatus
First Claim
1. An image processing apparatus for converting multigradation image data into bigradation image data of a first and second gradation value comprising:
- an error correction means to correct an input multigradation image data of a target pixel (data) by adding an error diffused from a proximal previously binary-coded pixel to said input to produce a corrected pixel data;
a threshold value setting means for setting a binary threshold value based on a gradation value of said input; and
a binary coding means which accepts said binary threshold value and said corrected pixel data and outputs said bigradation image data based on said threshold value and said corrected pixel data;
wherein said first and second gradation value have a median m and said threshold value setting means sets said binary coding threshold value slsh, satisfying at least one of the tolerance ranges shown in the following equations;
in the case where the value of input data is close to said first gradation value, data≦
slsh≦
((m+data)/2), and in the case where the value of input data is close to said second gradation value, ((m+data)/2)≦
slsh≦
data.
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Accused Products
Abstract
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.
40 Citations
9 Claims
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1. An image processing apparatus for converting multigradation image data into bigradation image data of a first and second gradation value comprising:
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an error correction means to correct an input multigradation image data of a target pixel (data) by adding an error diffused from a proximal previously binary-coded pixel to said input to produce a corrected pixel data; a threshold value setting means for setting a binary threshold value based on a gradation value of said input; and a binary coding means which accepts said binary threshold value and said corrected pixel data and outputs said bigradation image data based on said threshold value and said corrected pixel data;
wherein said first and second gradation value have a median m and said threshold value setting means sets said binary coding threshold value slsh, satisfying at least one of the tolerance ranges shown in the following equations;in the case where the value of input data is close to said first gradation value, data≦
slsh≦
((m+data)/2), and in the case where the value of input data is close to said second gradation value, ((m+data)/2)≦
slsh≦
data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification