Gradation data processing apparatus

Claim 1

A device for converting gradation data representative of the density level of a picture element of an original scanned image into extended gradation data for use in reproducing the original image, said original image being divided into an array of adjacent picture elements and being line-scanned from top to bottom, said device comprising: first means for extracting (a) binary gradation data D comprised of a digital word of predetermined length and representative of a selected picture element, (b) binary gradation data Du representative of a pucture element located above and adjacent to said selected picture element, and (c) binary gradation data D1 representative of a picture element located immediately to the side of said selected picture element; second means for executing the following calculations in order to obtain a binary gradation date D' consisting of digital words having more bits than said gradation data D; (a) D'=2·D+(Du+D1) when T 2 <δ<T 1 ; (b) D'=D max when T 1 <δ; and (c) D'=D min when δ<T 2 ; wherein δ=2·D-(Du+D1), T 1 is a first predetermined threshold value, T 2 is a second predetermined threshold value smaller than T 1 , D max is a predetermined maximum gradation value, and D min is a predetermined minimum gradation value; and third means for delivering the calculated binary gradation data D' representative of the density level of the selected picture element as extended gradation data for use in reproducing the original image.

Claim 2

A device for converting gradation data representative of the density level of a picture element of an original scanned image into extended gradation data for use in reproducing the original image, said original image being divided into an array of adjacent picture elements and being line-scanned from top to bottom, said device comprising: first means for extracting (a) binary gradation data D comprised of a digital word of predetermined length and representative of a selected picture element, (b) binary gradation data Du representative of a pucture element located above and adjacent to said selected picture element, and (c) binary gradation data D1 representative of a picture element located immediately to the side of said selected picture element; second means for executing the following calculations in order to obtain a binary gradation date D' consisting of digital words having more bits than said gradation data D; (a) D'=2·D+(Du+D1) when T 2 <δ<T 1 ; (b) D'=D max when T 1 <δ; and (c) D'=D min when δ<T 2 ; wherein δ=2·D-(Du+D1), T 1 is a first predetermined threshold value, T 2 is a second predetermined threshold value smaller than T 1 , D max is a predetermined maximum gradation value, and D min is a predetermined minimum gradation value; and third means for delivering the calculated binary gradation data D' representative of the density level of the selected picture element as extended gradation data for use in reproducing the original image.

Claim 14

A device for converting gradation data representative of the density level of a picture element of an original scanned image into extended gradation data ofr use in reproducing the original image, said original image being divided into an array of adjacent picture elements and being line-scanned from top to bottom, said device comprising: first means for extracting (a) binary gradation data D comprised of a digital word of predetermined length and representative of a selected picture leements, and (b) binary gradation data representative of a plurality of peripheral picture elements adjacent to said selected picture elements; second means for calculating the sum of theb binary gradation data of the plurality of peripheral picture elements; third means for multiplying the gradation data D by the number of the peripheral picture elements; fourth means for calculating the total sum of the sum output of said second means and the multiplication product of said third means; and fifth means for (a) delivering said total sum when T 2 <δ<T 1 , (b) delivering a first predetermined gradation value when T 1 <δ, and (c) delivering a second predetermined gradation value when δ<T 2 , as said extended gradation data for use in reproducing the original image, said extended gradation data being representative of the density level of said selected picture element being comprised of a digital word having more bits than said digital word defining said gradation data D, where T 1 is a first predetermined threshold value and T 2 is a second predetermined threshold value smaller than T 1 .

Claim 15

A device for converting gradation data representative of the density level of a picture element of an original scanned image into extended gradation data ofr use in reproducing the original image, said original image being divided into an array of adjacent picture elements and being line-scanned from top to bottom, said device comprising: first means for extracting (a) binary gradation data D comprised of a digital word of predetermined length and representative of a selected picture leements, and (b) binary gradation data representative of a plurality of peripheral picture elements adjacent to said selected picture elements; second means for calculating the sum of theb binary gradation data of the plurality of peripheral picture elements; third means for multiplying the gradation data D by the number of the peripheral picture elements; fourth means for calculating the total sum of the sum output of said second means and the multiplication product of said third means; and fifth means for (a) delivering said total sum when T 2 <δ<T 1 , (b) delivering a first predetermined gradation value when T 1 <δ, and (c) delivering a second predetermined gradation value when δ<T 2 , as said extended gradation data for use in reproducing the original image, said extended gradation data being representative of the density level of said selected picture element being comprised of a digital word having more bits than said digital word defining said gradation data D, where T 1 is a first predetermined threshold value and T 2 is a second predetermined threshold value smaller than T 1 .