Method and apparatus for creating a dither pattern

Claim 1

A method of creating a record in which a given color is rendered with a selected gray scale level, comprising: resolving an addressable area of a record medium into a multiplicity of addressable record locations, the record locations being in a rectangular array of rows and columns, organizing the addressable record locations into a plurality of groups each containing a rectangular array of m×n addressable record locations, where m and n are each greater than two, and each group having four locations in respective corners of the m×n array, organizing the groups into a plurality of dither cells each containing a rectangular array of M×N groups, whereby each dither cell contains M×N×m×n addressable record locations, applying the given color to j record locations in each group of at least one dither cell, where j is an integer in the range from zero to m×n-1, and in the event that j is greater than one, each of the j record locations in a group being in the same row or column as at least one other of the j record locations of that group, and in the event that j is less than ten, all j addressed record locations of that group being within a 3×3 array, with the record location at one corner of the 3×3 array being at one of the corners of the m×n array, and applying the given color to one additional record locationin each of i groups of said one dither cell, where i is an integer in the range from zero to M×N-1, in the event that j is greater than zero, the additional record location in each of the i groups being in the same row or column as at least one of the j record locations of that group, in the event that j is less than nine, the additional record location in each of the i groups being within said 3×3 array and in the event that i is greater than one, the i groups being distributed substantially uniformly over the dither cell.

Claim 2

A method of creating a record in which a given color is rendered with a selected gray scale level, comprising: resolving an addressable area of a record medium into a multiplicity of addressable record locations, the record locations being in a rectangular array of rows and columns, organizing the addressable record locations into a plurality of groups each containing a rectangular array of m×n addressable record locations, where m and n are each greater than two, and each group having four locations in respective corners of the m×n array, organizing the groups into a plurality of dither cells each containing a rectangular array of M×N groups, whereby each dither cell contains M×N×m×n addressable record locations, applying the given color to j record locations in each group of at least one dither cell, where j is an integer in the range from zero to m×n-1, and in the event that j is greater than one, each of the j record locations in a group being in the same row or column as at least one other of the j record locations of that group, and in the event that j is less than ten, all j addressed record locations of that group being within a 3×3 array, with the record location at one corner of the 3×3 array being at one of the corners of the m×n array, and applying the given color to one additional record locationin each of i groups of said one dither cell, where i is an integer in the range from zero to M×N-1, in the event that j is greater than zero, the additional record location in each of the i groups being in the same row or column as at least one of the j record locations of that group, in the event that j is less than nine, the additional record location in each of the i groups being within said 3×3 array and in the event that i is greater than one, the i groups being distributed substantially uniformly over the dither cell.

Claim 6

A method of creating a record from a sequence of R×S numerical values each in the range from 0 to M×N×m×n, where R, S, M, N, m, and n are positive integers and R and S are each much greater than M, N, m and n, comprising: resolving an addressable area of a record medium into a rectangular array of R×S addressable record locations, whereby the numerical values are associated with respective record locations, the record locations being in a rectangular array of rows and columns, organizing the R×S addressable record locations into a plurality of groups each containing a rectangular array of m×n addressable record locations, where m and n are each greater than two, and each group having four locations in respective corners of the m×n array, organizing the groups into a plurality of dither cells each containing a rectangular array of M×N groups, whereby each dither cell contains M×N×m×n addressable record locations, associating a reference value with each addressable location in each dither cell, the reference values being terms in a first progression which is substantially an arithmetic progression from zero to M×N×m×n and having a common difference of unity, the reference values associated with the record locations in each group being terms in a second progression which is substantially an arithmetic progression freom Q to [Q+(m×n×D)] Q+(m×n×(D-1)), where Q is the smallest of the reference values for the record locations in that group and D is equal to M×N, and the locations with which the second and each subsequent terms in the second progression are associated being in the same row or column as a location with which a preceding term in the second progression is associated, and the locations with which the first nine terms in the second progression are associated all being within a 3×3 array, with the record locations at one corner of the 3×3 array being at one of the corners of the m×n array, and the smallest of the reference values in the groups respectively being terms in a third progression which is substantially an arithmetic progression from zero to (M×N)-1 and the groups containing successive terms in the third progression being distributed substntially uniformly over the dither cell, and comparing the numerical value for a record location with the reference value for that location and, in the event that the numerical value and the reference value are in a predetermined relationship, applying color the record location and otherwise not applying color to that location.

Claim 7

A method of creating a record from a sequence of R×S numerical values each in the range from 0 to M×N×m×n, where R, S, M, N, m, and n are positive integers and R and S are each much greater than M, N, m and n, comprising: resolving an addressable area of a record medium into a rectangular array of R×S addressable record locations, whereby the numerical values are associated with respective record locations, the record locations being in a rectangular array of rows and columns, organizing the R×S addressable record locations into a plurality of groups each containing a rectangular array of m×n addressable record locations, where m and n are each greater than two, and each group having four locations in respective corners of the m×n array, organizing the groups into a plurality of dither cells each containing a rectangular array of M×N groups, whereby each dither cell contains M×N×m×n addressable record locations, associating a reference value with each addressable location in each dither cell, the reference values being terms in a first progression which is substantially an arithmetic progression from zero to M×N×m×n and having a common difference of unity, the reference values associated with the record locations in each group being terms in a second progression which is substantially an arithmetic progression freom Q to [Q+(m×n×D)] Q+(m×n×(D-1)), where Q is the smallest of the reference values for the record locations in that group and D is equal to M×N, and the locations with which the second and each subsequent terms in the second progression are associated being in the same row or column as a location with which a preceding term in the second progression is associated, and the locations with which the first nine terms in the second progression are associated all being within a 3×3 array, with the record locations at one corner of the 3×3 array being at one of the corners of the m×n array, and the smallest of the reference values in the groups respectively being terms in a third progression which is substantially an arithmetic progression from zero to (M×N)-1 and the groups containing successive terms in the third progression being distributed substntially uniformly over the dither cell, and comparing the numerical value for a record location with the reference value for that location and, in the event that the numerical value and the reference value are in a predetermined relationship, applying color the record location and otherwise not applying color to that location.