Threshold matrix, and method and apparatus of reproducing gray levels using threshold matrix

Claim 2

A gray level reproduction method which makes one-to-one correspondence between each pixel of an original image and each element of a threshold matrix, and represents a density of each pixel in an output image by binary or multivalue, wherein a dot pattern of which the size corresponds to said threshold matrix is divided into interspersed blocks of at least first and second groups of blocks and wherein said threshold matrix is created according to following conditions: (1) for each gray level of all gray levels, the number of dots in the dot pattern of the output image is equal in each of all the blocks; (2) for each gray level of all the gray levels, the dot pattern of the output image is mutually the same in each block of the first group of blocks; (3) for each gray level of all gray levels, the dot pattern of the output image is mutually different for at least some blocks of the second group of blocks; and (4) for increasing gray levels, the number of dots in the dot pattern of the output image is increased while substantially maintaining conformity of the dot patterns at a boundary corresponding to a boundary of the threshold matrix.

Claim 3

A method according to claim 1 , wherein the dot pattern is determined based on an averaged repulsion potential.

Claim 4

A method according to anyone of claim 1 or 2 , wherein said threshold matrix is created by controlling an order of dot increase between blocks of the first group and blocks of the second group.

Claim 5

A method according to claim 3 , wherein the blocks of the first group are preferential as the order of dot increase.

Claim 6

A method according to claim 1 , wherein a distance between dots in the dot pattern is controlled based on an averaged repulsion potential.

Claim 7

A method according to claim 1 , wherein when a block is further divided into four smaller blocks, the number of dots in an output image in each of all the smaller blocks is made equal in each of all of 4n gray levels (n is an integer).

Claim 8

A method according to claim 1 , wherein, when the threshold matrix is repeatedly used two dimensionally and periodically, a repeat direction is diverted to either a longitudinal direction or a lateral direction.

Claim 9

A method according to claim 1 , wherein a shape of the threshold matrix is different from a square.

Claim 10

A method according to claim 1 , wherein a color image is decomposed into plural color components, and the original image of at least one color component is input as an input image.

Claim 11

A gray level reproduction method which makes one-to-one correspondence between each pixel of an original image and each element of a threshold matrix, and represents a density of each pixel in an output image by binary or multivalue, wherein a dot pattern of which the size corresponds to said threshold matrix is divided into interspersed blocks of at least first and second groups of blocks and wherein said threshold matrix is created according to following conditions: (1) for each gray level of all gray levels, the number of dots in the dot pattern of the output image is equal in each of all the blocks; (2) for each gray level of all the gray levels, the dot pattern of the output image is mutually the same in each block of the first group of blocks; (3) for each gray level of all gray levels, the dot patterns of the output image is mutually different for at least some blocks of the second group of blocks; and (4) for increasing gray levels, an order of dot increase in the dot pattern of the output image is controlled between the blocks of the first group and the blocks of the second group.

Claim 12

A gray level reproduction method which makes one-to-one correspondence between each pixel of an original image and each element of a threshold matrix, and represents a density of each pixel in an output image by binary or multivalue, wherein a dot pattern of which the size corresponds to said threshold matrix is divided into interspersed blocks of at least first and second groups of blocks and wherein said threshold matrix is created according to following conditions: (1) for each gray level of all gray levels, the number of dots in the dot pattern of the output image is equal in each of all the blocks; (2) for each gray level of all the gray levels, the dot pattern of the output image is mutually the same in each block of the first group of blocks; (3) for each gray level of all gray levels, the dot patterns of the output image is mutually different for at least some blocks of the second group of blocks; and (4) for increasing gray levels, an order of dot increase in the dot pattern of the output image is controlled between the blocks of the first group and the blocks of the second group.

Claim 13

A method according to claim 10 , wherein the blocks of the first group are preferential as the order of dot increase.

Claim 14

A method according to claim 10 , wherein the dot pattern is determined based on an averaged repulsion potential.

Claim 15

A method according to claim 10 , wherein when a block is further divided into four smaller blocks, the number of dots in an output image in each of all the smaller blocks is made equal in each of all of 4n gray levels (n is an integer).

Claim 16

A method according to claim 10 , wherein, when the threshold matrix is repeatedly used two-dimensionally and periodically, a repeat direction is diverted to either a longitudinal direction or a lateral direction.

Claim 17

A method according to claim 10 , wherein a shape of the threshold matrix is different from a square.

Claim 18

A method according to claim 10 , wherein a color image is decomposed into plural color components, and the original image of at least one color component is input as an input image.

Claim 19

A gray level reproduction apparatus which makes one-to-one correspondence between each pixel of an original image and each element of a threshold matrix, and represents a density of each pixel in an output image by binary or multivalue, wherein, a dot pattern of which the size corresponds to said threshold matrix is divided into interspersed blocks of at least first and second groups of blocks and wherein said threshold matrix is created according to the following conditions: (1) for each gray level of all gray levels, the number of dots in the dot pattern of the output image is equal in each of all the blocks, (2) for each gray level of all gray levels, the dot pattern of the output image is mutually the same in each block of the first group of blocks, (3) for each gray level of all the gray levels, the dot pattern of the output image is mutually different for at least some blocks of the second group of blocks, and (4) for increasing gray levels, the number of dots in the dot pattern of the output image is increased while substantially maintaining conformity of the dot patterns at a boundary corresponding to a boundary of the threshold matrix, said apparatus comprising: storage means for storing said threshold matrix; comparison means for comparing as a threshold the value of said threshold matrix with the density of each pixel of the original image for each pixel; and output means for outputting the binary- or multivalue-processed dot pattern according to the comparison result of said comparison means.

Claim 20

A gray level reproduction apparatus which makes one-to-one correspondence between each pixel of an original image and each element of a threshold matrix, and represents a density of each pixel in an output image by binary or multivalue, wherein, a dot pattern of which the size corresponds to said threshold matrix is divided into interspersed blocks of at least first and second groups of blocks and wherein said threshold matrix is created according to the following conditions: (1) for each gray level of all gray levels, the number of dots in the dot pattern of the output image is equal in each of all the blocks, (2) for each gray level of all gray levels, the dot pattern of the output image is mutually the same in each block of the first group of blocks, (3) for each gray level of all the gray levels, the dot pattern of the output image is mutually different for at least some blocks of the second group of blocks, and (4) for increasing gray levels, the number of dots in the dot pattern of the output image is increased while substantially maintaining conformity of the dot patterns at a boundary corresponding to a boundary of the threshold matrix, said apparatus comprising: storage means for storing said threshold matrix; comparison means for comparing as a threshold the value of said threshold matrix with the density of each pixel of the original image for each pixel; and output means for outputting the binary- or multivalue-processed dot pattern according to the comparison result of said comparison means.

Claim 21

An apparatus according to claim 17 , wherein said threshold matrix is created by controlling order of dot increase between the blocks of the first group and the blocks of the second group.

Claim 22

A gray level reproduction apparatus which makes one-to-one correspondence between each pixel of an original image and each element of a threshold matrix, and represents a density of each pixel in an output image by binary or multivalue, wherein, a dot pattern of which the size corresponds to said threshold matrix is divided into interspersed blocks of at least first and second groups of blocks and wherein said threshold matrix is created according to the following conditions: (1) for each gray level of all gray levels, the number of dots in the dot pattern of the output image is equal in each of all the blocks, (2) for each gray level of all the gray levels, the dot pattern of the output image is mutually the same in each block of the first group of blocks, (3) for each gray level of all gray levels, the dot pattern of the output image is mutually different for at least some blocks of the second group of blocks, and (4) for increasing gray levels, an order of dot increase in the dot pattern of the output image is controlled between the blocks of the first group and the blocks of the second group, said apparatus comprising: storage means for storing said threshold matrix; comparison means for comparing as a threshold the value of said threshold matrix with the density of each pixel of the original image for each pixel; and output means for outputting the binary- or multivalue-processed dot pattern according to the comparison result of said comparison means.

Claim 23

A gray level reproduction apparatus which makes one-to-one correspondence between each pixel of an original image and each element of a threshold matrix, and represents a density of each pixel in an output image by binary or multivalue, wherein, a dot pattern of which the size corresponds to said threshold matrix is divided into interspersed blocks of at least first and second groups of blocks and wherein said threshold matrix is created according to the following conditions: (1) for each gray level of all gray levels, the number of dots in the dot pattern of the output image is equal in each of all the blocks, (2) for each gray level of all the gray levels, the dot pattern of the output image is mutually the same in each block of the first group of blocks, (3) for each gray level of all gray levels, the dot pattern of the output image is mutually different for at least some blocks of the second group of blocks, and (4) for increasing gray levels, an order of dot increase in the dot pattern of the output image is controlled between the blocks of the first group and the blocks of the second group, said apparatus comprising: storage means for storing said threshold matrix; comparison means for comparing as a threshold the value of said threshold matrix with the density of each pixel of the original image for each pixel; and output means for outputting the binary- or multivalue-processed dot pattern according to the comparison result of said comparison means.

Claim 24

A threshold matrix which is used to be compared with each pixel of an original image to represent a density of each pixel in an output image by binary or multivalue, wherein a dot pattern of which the size corresponds to said threshold matrix is divided into interspersed blocks of at least first and second groups of blocks, and wherein said threshold matrix is created according to the following conditions: (1) for each gray level of all gray levels the number of dots in the dot pattern of the output image is equal in each of all the blocks; (2) for each gray level of all the gray levels, the dot pattern of the output image is mutually the same in each block of the first group of blocks; (3) for each gray level of all gray levels, the dot pattern of the output image is mutually different for at least some blocks of the second group of blocks; and (4) for increasing gray levels, the number of dots in the dot pattern of the output image is increased while substantially maintaining conformity of the dot patterns at a boundary corresponding to a boundary of the threshold matrix.

Claim 25

A threshold matrix which is used to be compared with each pixel of an original image to represent a density of each pixel in an output image by binary or multivalue, wherein a dot pattern of which the size corresponds to said threshold matrix is divided into interspersed blocks of at least first and second groups of blocks, and wherein said threshold matrix is created according to the following conditions: (1) for each gray level of all gray levels the number of dots in the dot pattern of the output image is equal in each of all the blocks; (2) for each gray level of all the gray levels, the dot pattern of the output image is mutually the same in each block of the first group of blocks; (3) for each gray level of all gray levels, the dot pattern of the output image is mutually different for at least some blocks of the second group of blocks; and (4) for increasing gray levels, the number of dots in the dot pattern of the output image is increased while substantially maintaining conformity of the dot patterns at a boundary corresponding to a boundary of the threshold matrix.

Claim 26

A threshold matrix according to claim 20 , wherein said threshold matrix is created by controlling order of dot increase between the blocks of the first group and the blocks of the second group.

Claim 27

A threshold matrix which is used to be compared with each pixel of an original image to represent a density of each pixel in an output image by binary or multivalue, wherein a dot pattern of which the size corresponds to said threshold matrix is divided into interspersed blocks of at least first and second groups of blocks, and wherein said threshold matrix is created according to the following conditions: (1) for each gray level of all gray levels, the number of dots in the dot pattern of the output image is equal in each of all the blocks; (2) for each gray level of all the gray levels, the dot pattern of the output image is mutually the same in each block of the first group of blocks; (3) for each gray level of all gray levels, the dot pattern of the output image is mutually different for at least some blocks of the second group of blocks; and (4) for increasing gray levels, an order of dot increase in the dot pattern of the output image is controlled between the blocks of the first group and the blocks of the second group.

Claim 28

A threshold matrix which is used to be compared with each pixel of an original image to represent a density of each pixel in an output image by binary or multivalue, wherein a dot pattern of which the size corresponds to said threshold matrix is divided into interspersed blocks of at least first and second groups of blocks, and wherein said threshold matrix is created according to the following conditions: (1) for each gray level of all gray levels, the number of dots in the dot pattern of the output image is equal in each of all the blocks; (2) for each gray level of all the gray levels, the dot pattern of the output image is mutually the same in each block of the first group of blocks; (3) for each gray level of all gray levels, the dot pattern of the output image is mutually different for at least some blocks of the second group of blocks; and (4) for increasing gray levels, an order of dot increase in the dot pattern of the output image is controlled between the blocks of the first group and the blocks of the second group.

Claim 29

A computer-readable storage medium which stores a computer-executable control program to control a gray level reproduction process which makes one-to-one correspondence between each pixel of an original image and each element of a threshold matrix and represents a density of each pixel in an output image by binary or multivalue, wherein, a dot pattern of which the size corresponds to said threshold matrix is divided into interspersed blocks of at least first and second groups of blocks and wherein said threshold matrix is created according to the following conditions: (1) for each gray level of all gray levels, the number of dots in the dot pattern of the output image is equal in each of all the blocks, (2) for each gray level of all gray levels, the dot pattern of the output image mutually the same in each block of the first group of blocks, (3) for each gray level of all the gray levels, the dot pattern of the output image is mutually different for at least some blocks of the second group of blocks, and (4) for increasing gray levels, the number of dots in the dot pattern of the output image is increased while substantially maintaining conformity of the dot patterns at a boundary corresponding to a boundary of the threshold matrix, said control program comprising: a comparison step for comparing a threshold value of the threshold matrix with the density of each pixel of the original image for each pixel; and an output step for outputting the binary- or multivalue-processed dot pattern according to the comparison result of said comparison step.

Claim 30

A computer-readable storage medium which stores a computer-executable control program to control a gray level reproduction process which makes one-to-one correspondence between each pixel of an original image and each element of a threshold matrix and represents a density of each pixel in an output image by binary or multivalue, wherein, a dot pattern of which the size corresponds to said threshold matrix is divided into interspersed blocks of at least first and second groups of blocks and wherein said threshold matrix is created according to the following conditions: (1) for each gray level of all gray levels, the number of dots in the dot pattern of the output image is equal in each of all the blocks, (2) for each gray level of all gray levels, the dot pattern of the output image mutually the same in each block of the first group of blocks, (3) for each gray level of all the gray levels, the dot pattern of the output image is mutually different for at least some blocks of the second group of blocks, and (4) for increasing gray levels, the number of dots in the dot pattern of the output image is increased while substantially maintaining conformity of the dot patterns at a boundary corresponding to a boundary of the threshold matrix, said control program comprising: a comparison step for comparing a threshold value of the threshold matrix with the density of each pixel of the original image for each pixel; and an output step for outputting the binary- or multivalue-processed dot pattern according to the comparison result of said comparison step.

Claim 31

A computer-readable storage medium according to claim 23 , wherein said threshold matrix is created by controlling order of dot increase between the blocks of the first group and the blocks of the second group.

Claim 32

A computer-readable storage medium which stores a computer-executable control program to control a gray level reproduction process which makes one-to-one correspondence between each pixel of an original image and each element of a threshold matrix and represents a density of each pixel in an output image by binary or multivalue, wherein, a dot pattern of which the size corresponds to said threshold matrix is divided into interspersed blocks of at least first and second groups of blocks and wherein said threshold matrix is created according to the following conditions: (1) for each gray level of all gray levels, the number of dots in the dot pattern of the output image is equal in each of all the blocks, (2) for each gray level of all gray levels, the dot pattern of the output image is mutually the same in each block of the first group of blocks, (3) for each gray level of all the gray levels, the dot pattern of the output image is mutually different for at least some blocks of the second group of blocks, and (4) for increasing gray levels, and order of dot increase in the dot pattern of the output image is controlled between the blocks of the first group and the blocks of the second group, said control program comprising: a comparison step for comparing the threshold value of the threshold matrix with the density of each pixel of the original image for each pixel; and an output step for outputting the binary- or multivalue-processed dot pattern according to the comparison result of said comparison step.

Claim 33

A computer-readable storage medium which stores a computer-executable control program to control a gray level reproduction process which makes one-to-one correspondence between each pixel of an original image and each element of a threshold matrix and represents a density of each pixel in an output image by binary or multivalue, wherein, a dot pattern of which the size corresponds to said threshold matrix is divided into interspersed blocks of at least first and second groups of blocks and wherein said threshold matrix is created according to the following conditions: (1) for each gray level of all gray levels, the number of dots in the dot pattern of the output image is equal in each of all the blocks, (2) for each gray level of all gray levels, the dot pattern of the output image is mutually the same in each block of the first group of blocks, (3) for each gray level of all the gray levels, the dot pattern of the output image is mutually different for at least some blocks of the second group of blocks, and (4) for increasing gray levels, and order of dot increase in the dot pattern of the output image is controlled between the blocks of the first group and the blocks of the second group, said control program comprising: a comparison step for comparing the threshold value of the threshold matrix with the density of each pixel of the original image for each pixel; and an output step for outputting the binary- or multivalue-processed dot pattern according to the comparison result of said comparison step.