Image processor and image processing method handling multilevel image data
First Claim
Patent Images
1. An image processor comprising:
- a gradation converter for converting pixel data represented with m gradations into pixel data represented with n gradations;
an error calculation circuit for calculating an error generated by the conversion of said gradation converter;
an error diffusing circuit for diffusing the error calculated by said error calculation circuit to peripheral pixels situated on the periphery of a target pixel;
a selecting unit for selecting a data processing mode; and
an weight assigning circuit for adding a weight assigning value corresponding to the data processing mode selected by the selecting unit to the pixel data of the peripheral pixel to be converted; and
wherein m and n are both given integers and satisfy 2<
n <
m and the weight assigning value added by the weight assigning circuit is decided in accordance with the value of n.
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Abstract
An image processor converts pixel data represented with m gradations into pixel data represented with n gradations by using the error diffusion method. The m and n are both given integers and satisfy 2<n<m. Not only the error but also a weight assigning value is added to pixel data to be converted. The weight assigning value is determined according to the values of m and n.
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Citations
13 Claims
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1. An image processor comprising:
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a gradation converter for converting pixel data represented with m gradations into pixel data represented with n gradations;
an error calculation circuit for calculating an error generated by the conversion of said gradation converter;
an error diffusing circuit for diffusing the error calculated by said error calculation circuit to peripheral pixels situated on the periphery of a target pixel;
a selecting unit for selecting a data processing mode; and
an weight assigning circuit for adding a weight assigning value corresponding to the data processing mode selected by the selecting unit to the pixel data of the peripheral pixel to be converted; and
wherein m and n are both given integers and satisfy 2<
n <
m and the weight assigning value added by the weight assigning circuit is decided in accordance with the value of n.- View Dependent Claims (2, 3, 4, 5)
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6. An image processor comprising:
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a gradation converter for converting pixel data represented with m gradations into pixel data represented with n gradations;
an error calculation circuit for calculating an error generated by the conversion of said gradation converter;
an error diffusing circuit for diffusing the error calculated by said error calculation circuit to peripheral pixels situated on the periphery of a target pixel;
a selecting unit for selecting a data processing mode; and
an weight assigning circuit for adding a weight assigning value corresponding to the data processing mode selected by the selecting unit to the pixel data of the peripheral pixel to be converted; and
wherein m and n are both given integers and satisfy 2<
n <
m,wherein said weight assigning circuit includes a plurality of weight assigning matrices and a selector for selecting one from said weight assigning matrices according to the processing mode selected by the selecting unit, wherein said weight assigning circuit further includes a weight correction circuit for correcting the weight assigning value according to the value of m and n.
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7. An image processor comprising:
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a gradation converter for converting pixel data represented with m gradations into pixel data represented with n gradations, wherein m and n are both given integers and satisfy 2<
n<
m;
an error calculation circuit for calculating an error generated by the conversion of said gradation converter;
an error diffusing circuit for diffusing the error calculated by said error calculation circuit to peripheral pixels situated on the periphery of a target pixel; and
an weight assigning circuit for adding a weight assigning value decided according to the value of the n to the pixel data of the peripheral pixel to be converted. - View Dependent Claims (8, 9, 10, 11)
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12. An image processing method comprising steps of:
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converting pixel data represented with m gradations into pixel data represented with n gradations;
calculating an error generated by the conversion of said converting step;
diffusing the calculated to peripheral pixels situated on the periphery of a target pixel;
selecting a data processing mode; and
adding a weight assigning value corresponding to the selected data processing mode to the pixel data of the peripheral pixel to be converted; and
wherein m an n are both given integers and satisfy 2<
n <
m,wherein the weight assigning value added in said adding step is decided in accordance with the value of n.
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13. An image processing method comprising steps of:
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converting pixel data represented with m gradations into pixel data represented with n gradations, wherein m and n are both given integers and satisfy 2<
n<
m;
calculating an error generated by the conversion of said converting step;
diffusing the calculated error to peripheral pixels situated on the periphery of a target pixel; and
adding a weight assigning value decided according to the value of n to the pixel data of the peripheral pixel to be converted.
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Specification