Image processing apparatus with correction of diffusion errors of overlapping dots

Claim 2

An image processing apparatus comprising; an error memory for storing error data as diffused; adding means for adding the error data as diffused from adjacent pixels read out of said error memory to input multi-tone image data; binary coding means for comparing the multi-tone image data supplied from said adding means with a predetermined threshold level thereby to produce binary data; error calculation means for outputting, as error data, a difference between the input data to said binary coding means and a tone value n obtained when a dot is generated or a tone value O obtained when no dot is generated and modifying the error data depending on a jut-out area from the adjacent pixels; and a jut-out pattern memory for storing correction factors in correspondence to patterns of overlapping of the adjacent dots.

Claim 3

An image processing apparatus according to claim 1, wherein said jut-out pattern memory stores, as a correction factor, the ratio of a total area of jut-out areas from the adjacent pixels to a theoretical pixel area.

Claim 4

An image processing apparatus comprising: an error memory for storing error data as diffused; adding means for adding the error data as diffused from adjacent pixels read out of said error memory to input multi-tone image data; binary coding means for comparing the multi-tone image data supplied from said adding means with a predetermined threshold level thereby to produce binary data; error calculation means for outputting, as error data, a difference between the input data to said binary coding means and a tone value n obtained when a dot is generated or a tone value O obtained when no dot is generated and modifying the error data depending on a jut-out area from the adjacent pixels; and wherein said error calculation means calculates the error data such that, when a dot is generated, and the dot includes a jut-out area into the adjacent pixel, for which it is already determined to generate no dot, the error data is calculated on an assumption that a dot has a tone level n+β higher than the tone level n expected, when the dot is generated.

Claim 5

An image processing apparatus comprising: an error memory for storing error data as diffused; adding means for adding the error data as diffused from adjacent pixels read out of said error memory to input multi-tone image data; binary coding means for comparing the multi-tone image data supplied from said adding means with a predetermined threshold level thereby to produce binary data; error calculation means for outputting, as error data, a difference between the input data to said binary coding means and a tone value n obtained when a dot is generated or a tone value O obtained when no dot is generated and modifying the error data depending on a jut-out area from the adjacent pixels; and wherein said error calculation means calculates the error data such that, when a dot is generated, and the dot includes a jut-out area into the adjacent pixel, for which it is already determined to generate no dot, the error data is calculated on an assumption that a dot has a tone level n+β higher than the tone level n expected, when the dot is generated.

Claim 6

An image processing apparatus comprising: an error memory for storing error data as diffused; adding means for adding the error data as diffused from adjacent pixels read out of said error memory to input multi-tone image data; binary coding means for comparing the multi-tone image data supplied from said adding means with a predetermined threshold level thereby to produce binary data; error calculation means for outputting, as error data, a difference between the input data to said binary coding means and a tone value n obtained when a dot is generated or a tone value O obtained when no dot is generated and modifying the error data depending on a jut-out area from the adjacent pixels; and wherein said error calculation means modifies the error data, when no dot is generated, and a dot of the adjacent pixel, for which it is already determined to generate the dot, juts out therein, by subtracting from the error data a value corresponding to the jut-out area of the dot for the adjacent pixel.

Claim 7

An image processing apparatus comprising: an error memory for storing error data as diffused; adding means for adding the error data as diffused from adjacent pixels read out of said error memory to input multi-tone image data; binary coding means for comparing the multi-tone image data supplied from said adding means with a predetermined threshold level thereby to produce binary data; error calculation means for outputting, as error data, a difference between the input data to said binary coding means and a tone value n obtained when a dot is generated or a tone value O obtained when no dot is generated and modifying the error data depending on a jut-out area from the adjacent pixels; and wherein said error calculation means modifies the error data, when no dot is generated, and a dot of the adjacent pixel, for which it is already determined to generate the dot, juts out therein, by subtracting from the error data a value corresponding to the jut-out area of the dot for the adjacent pixel.

Claim 8

An image processing apparatus comprising: an error memory for storing error data to be diffused; correcting means for correcting input multi-tone image data for each pixel by the error data to be diffused from an adjacent pixel as stored in the error memory, thereby producing a corrected multi-tone image data; binary coding means for comparing the corrected multi-tone image data with a predetermined threshold level thereby to produce binary data for the pixel; and error calculation means for calculating the error data for each pixel, as a difference between the corrected multi-tone image data for the pixel and a predetermined first tone value when a dot is to be generated for the pixel or a predetermined second tone value when no dot is to be generated for the pixel, said error calculation means including means for substituting said first tone value by a predetermined third tone value higher than said first tone value for calculation of the error data, when a dot is to be generated for the pixel and the dot includes a jut-out area into an adjacent pixel for which it is already determined to generate no dot.

Claim 9

An image processing apparatus comprising: an error memory for storing error data to be diffused; correcting means for correcting input multi-tone image data for each pixel by the error data to be diffused from an adjacent pixel as stored in the error memory, thereby producing a corrected multi-tone image data; binary coding means for comparing the corrected multi-tone image data with a predetermined threshold level thereby to produce binary data for the pixel; and error calculation means for calculating the error data for each pixel, as a difference between the corrected multi-tone image data for the pixel and a predetermined first tone value when a dot is to be generated for the pixel or a predetermined second tone value when no dot is to be generated for the pixel, said error calculation means including means for substituting said first tone value by a predetermined third tone value higher than said first tone value for calculation of the error data, when a dot is to be generated for the pixel and the dot includes a jut-out area into an adjacent pixel for which it is already determined to generate no dot.

Claim 10

An image processing apparatus comprising: an error memory for storing error data to be diffused; correcting means for correcting input multi-tone image data for each pixel by the error data to be diffused from an adjacent pixel as stored in the error memory, thereby producing a corrected multi-tone image data; binary coding means for comparing the corrected multi-tone image data with a predetermined threshold level thereby to produce binary data for the pixel; and error calculation means for calculating the error data for each pixel, as a difference between the corrected multi-tone image data for the pixel and a predetermined first tone value when a dot is to be generated for the pixel or a predetermined second tone value when no dot is to be generated for the pixel, said error calculation means including means for modifying the corrected multi-tone image data before calculation of the error data, when no dot is to be generated for the pixel and a dot of an adjacent pixel, for which it is already determined to generate the dot, includes a jut-out area jutting-out into the pixel, by subtracting a value corresponding to the jut-out area of the dot of the adjacent pixel from the corrected multi-tone image data.

Claim 11

An image processing apparatus comprising: an error memory for storing error data to be diffused; correcting means for correcting input multi-tone image data for each pixel by the error data to be diffused from an adjacent pixel as stored in the error memory, thereby producing a corrected multi-tone image data; binary coding means for comparing the corrected multi-tone image data with a predetermined threshold level thereby to produce binary data for the pixel; and error calculation means for calculating the error data for each pixel, as a difference between the corrected multi-tone image data for the pixel and a predetermined first tone value when a dot is to be generated for the pixel or a predetermined second tone value when no dot is to be generated for the pixel, said error calculation means including means for modifying the corrected multi-tone image data before calculation of the error data, when no dot is to be generated for the pixel and a dot of an adjacent pixel, for which it is already determined to generate the dot, includes a jut-out area jutting-out into the pixel, by subtracting a value corresponding to the jut-out area of the dot of the adjacent pixel from the corrected multi-tone image data.

Claim 12

An image processing apparatus comprising: an error memory for storing error data to be diffused; correcting means for correcting input multi-tone image data for each pixel by the error data to be diffused from an adjacent pixel as stored in the error memory, thereby producing a corrected multi-tone image data; binary coding means for comparing the corrected multi-tone image data with a predetermined threshold level thereby to produce binary data for the pixel; and error calculation means for calculating the error data for each pixel, as a difference between the corrected multi-tone image data for the pixel and a predetermined first tone value when a dot is to be generated for the pixel or a predetermined second tone value when no dot is to be generated for the pixel, wherein said first tone value is substituted by a predetermined third tone value higher than said first tone value before calculation of the error data when the dot to be generated for the pixel includes a jut-out area into an adjacent pixel, for which it is already determined to generate no dot, and the corrected multi-tone image data is modified before calculation of the error data, when no dot is to be generated for the pixel and a dot of an adjacent pixel, for which is already determined to generate the dot, includes a jut-out area jutting-out into the pixel, by subtracting a value corresponding to the jut-out area of the dot of the adjacent pixel from the corrected multi-tone image data.

Claim 13

An image processing apparatus comprising: an error memory for storing error data to be diffused; correcting means for correcting input multi-tone image data for each pixel by the error data to be diffused from an adjacent pixel as stored in the error memory, thereby producing a corrected multi-tone image data; binary coding means for comparing the corrected multi-tone image data with a predetermined threshold level thereby to produce binary data for the pixel; and error calculation means for calculating the error data for each pixel, as a difference between the corrected multi-tone image data for the pixel and a predetermined first tone value when a dot is to be generated for the pixel or a predetermined second tone value when no dot is to be generated for the pixel, wherein said first tone value is substituted by a predetermined third tone value higher than said first tone value before calculation of the error data when the dot to be generated for the pixel includes a jut-out area into an adjacent pixel, for which it is already determined to generate no dot, and the corrected multi-tone image data is modified before calculation of the error data, when no dot is to be generated for the pixel and a dot of an adjacent pixel, for which is already determined to generate the dot, includes a jut-out area jutting-out into the pixel, by subtracting a value corresponding to the jut-out area of the dot of the adjacent pixel from the corrected multi-tone image data.