Apparatus and method for producing a half-tone image

Claim 3

The method recited in claim 1 wherein the scanning is performed in two dimensions.

Claim 4

The method recited in claim 1 wherein the error is allocated in two dimensions.

Claim 5

The method recited in claim 3 wherein the error is allocated equally in each of the two dimensions.

Claim 6

The method recited in claim 1 wherein the black dots and white dots are produced by marking and not marking the medium, respectively.

Claim 9

The apparatus recited in claim 6 wherein the scanning is performed in two dimensions.

Claim 10

The apparatus recited in claim 6 wherein the error is allocated in two dimensions.

Claim 11

The apparatus recited in claim 8 wherein the error is allocated equally in each of the two dimensions.

Claim 12

The apparatus recited in claim 6 wherein the black and white dots correspond to marking and not marking the output medium, respectively.

Claim 13

An image reproducing system, comprising: a) a scanning means for reading input image data corresponding to the image to be reproduced; b) a screening device comprising: memory means for storing image data representative of sequences of pluralities of input points and which contain information used to direct a marking device to mark or not mark indicia on a medium; means for generating signals allocating the marking and not marking of the indicia on the medium based on a value of a current input point in a sequence of input points, a previous output signal corresponding to a previous input point in the sequence and an error representing a difference between the previous input point and the corresponding output signals scaled relative to a maximum gray scale, the error influencing output signals for subsequent input points in the sequence; and c) a marking device to receive the output signals from the screening device, whereby the marking device marks variable size dots comprising indicia corresponding to said output signals.

Claim 14

An image reproducing system, comprising: a) a scanning means for reading input image data corresponding to the image to be reproduced; b) a screening device comprising: memory means for storing image data representative of sequences of pluralities of input points and which contain information used to direct a marking device to mark or not mark indicia on a medium; means for generating signals allocating the marking and not marking of the indicia on the medium based on a value of a current input point in a sequence of input points, a previous output signal corresponding to a previous input point in the sequence and an error representing a difference between the previous input point and the corresponding output signals scaled relative to a maximum gray scale, the error influencing output signals for subsequent input points in the sequence; and c) a marking device to receive the output signals from the screening device, whereby the marking device marks variable size dots comprising indicia corresponding to said output signals.

Claim 15

The apparatus recited in claim 11 wherein the scanning device scans a plurality of lines corresponding to the image and the sequence corresponds to a plurality of points on at least one line.

Claim 16

The method recited in claim 1 wherein the recursive relationship employs a constant and a plurality of previous outputs, the constant and the plurality of previous outputs determining the coarseness of the screened image.

Claim 17

The method recited in claim 13 wherein the constant and the plurality of previous outputs define an allowable excursion of the error around zero.

Claim 18

The apparatus recited in claim 6 wherein the recursive relationship employs a constant and a plurality of previous outputs, the constant and the plurality of previous outputs determining the coarseness of the screened image.

Claim 19

The apparatus recited in claim 15 wherein the constant and the plurality of previous outputs define an allowable excursion of the error around zero.

Claim 20

An image reproducing system for generating on an output medium an image corresponding to an original image, the system comprising: a) a scanning means for reading input data of the original image to be reproduced, the scanning means generating signals representing gray scale values corresponding to each pixel of the original; b) a screening device comprising: memory means for storing the image data corresponding to each pixel and a plurality of output signals which direct a marking device to mark one of black or white indicia on the output medium for each output signal, each output signal corresponding to a pixel on the output medium; and means for generating signals allocating the black or white indicia on the output medium based on the gray scale value of a current gray scale signal, a previous output signal and an error signal representing a difference between prior gray scale signals and at least one previously generated output signal; and c) a marking device to receive the output signals from the screening device, the marking device thereby generating variable size dots comprising indicia corresponding to the output signals.

Claim 21

An image reproducing system for generating on an output medium an image corresponding to an original image, the system comprising: a) a scanning means for reading input data of the original image to be reproduced, the scanning means generating signals representing gray scale values corresponding to each pixel of the original; b) a screening device comprising: memory means for storing the image data corresponding to each pixel and a plurality of output signals which direct a marking device to mark one of black or white indicia on the output medium for each output signal, each output signal corresponding to a pixel on the output medium; and means for generating signals allocating the black or white indicia on the output medium based on the gray scale value of a current gray scale signal, a previous output signal and an error signal representing a difference between prior gray scale signals and at least one previously generated output signal; and c) a marking device to receive the output signals from the screening device, the marking device thereby generating variable size dots comprising indicia corresponding to the output signals.

Claim 22

The apparatus recited in claim 17 wherein the black and white indicia correspond to marking and not marking of the output medium, respectively.

Claim 23

An image reproducing system, comprising: a) a scanning means for reading input image data corresponding to the image to be reproduced; b) a screening device comprising: memory means for storing image data representative of sequences of pluralities of input points and which contain information used to direct a marking device to mark or not mark indicia on a medium, and means for generating signals allocating the marking and not marking of the indicia on the medium, including means for generating variable size dots formed by a plurality of adjacent dots, the variable size of said plurality of adjacent dots being determined from a recursive relationship based on a value of a current input point in a sequence of input points, a previous output signal corresponding to a previous input point in the sequence and an error representing a difference between the previous input point and the corresponding output signals scaled relative to a maximum gray scale, the error influencing output signals for subsequent input points in the sequence; and c) a marking device to receive the output signals from the screening device, whereby the marking device marks variable size dots comprising indicia corresponding to said output signals.

Claim 24

An image reproducing system, comprising: a) a scanning means for reading input image data corresponding to the image to be reproduced; b) a screening device comprising: memory means for storing image data representative of sequences of pluralities of input points and which contain information used to direct a marking device to mark or not mark indicia on a medium, and means for generating signals allocating the marking and not marking of the indicia on the medium, including means for generating variable size dots formed by a plurality of adjacent dots, the variable size of said plurality of adjacent dots being determined from a recursive relationship based on a value of a current input point in a sequence of input points, a previous output signal corresponding to a previous input point in the sequence and an error representing a difference between the previous input point and the corresponding output signals scaled relative to a maximum gray scale, the error influencing output signals for subsequent input points in the sequence; and c) a marking device to receive the output signals from the screening device, whereby the marking device marks variable size dots comprising indicia corresponding to said output signals.

Claim 25

An image reproducing system for generating on an output medium an image corresponding to an original image, the system comprising: a) a scanning means for reading input data of the original image to be reproduced, the scanning means generating signals representing gray scale values corresponding to each pixel of the original; b) a screening device comprising: memory means for storing the image data corresponding to each pixel and a plurality of output signals which direct a marking device to mark one of black or white indicia on the output medium for each output signal, each output signal corresponding to a pixel on the output medium, and means for generating signals allocating the black or white indicia on the output medium, including means for generating variable size dots formed by a plurality of adjacent dots, the variable size of said plurality of adjacent dots being determined from a recursive relationship based on the gray scale value of a current gray scale signal, a previous output signal and an error signal representing a difference between previous gray scale signals and at least one previously generated output signal; and c) a marking device to receive the output signals from the screening device, the marking device thereby generating variable size dots comprising indicia corresponding to the output signals.

Claim 26

An image reproducing system for generating on an output medium an image corresponding to an original image, the system comprising: a) a scanning means for reading input data of the original image to be reproduced, the scanning means generating signals representing gray scale values corresponding to each pixel of the original; b) a screening device comprising: memory means for storing the image data corresponding to each pixel and a plurality of output signals which direct a marking device to mark one of black or white indicia on the output medium for each output signal, each output signal corresponding to a pixel on the output medium, and means for generating signals allocating the black or white indicia on the output medium, including means for generating variable size dots formed by a plurality of adjacent dots, the variable size of said plurality of adjacent dots being determined from a recursive relationship based on the gray scale value of a current gray scale signal, a previous output signal and an error signal representing a difference between previous gray scale signals and at least one previously generated output signal; and c) a marking device to receive the output signals from the screening device, the marking device thereby generating variable size dots comprising indicia corresponding to the output signals.

Claim 27

An image reproducing system comprising: a) a scanning means for reading input image data corresponding to the image to be reproduced; b) a screening device comprising: memory means for storing image data representative of sequences of pluralities of input points and which contain information used to direct a marking device to mark or not mark indicia on a medium, and means for generating signals allocating the marking and not marking of the indicia on the medium based on a value of a current input point in a sequence of input points, a previous output signal corresponding to a previous input point in the sequence and an error representing a difference between the previous input points and the corresponding output signals scaled relative to a maximum gray scale, the error influencing output signals for subsequent input points in the sequence; and c) a marking device to receive the output signals from the screening device, whereby the marking device marks variable size dots comprising indicia corresponding to said output signals, wherein said variable size dots are determined from a recursive relationship between said current input point in a sequence of input points, said previous output signal corresponding to a previous input point in the sequence and said error representing a difference between the previous input points and the corresponding output signals; and means responsive to a prior output signal corresponding to indicia of said halftone screen prior to said present output signal, and coupled to said means for generating signals to tend make said present output signal the same value as a prior adjacent output signal, thereby forming a variable size dot comprising a plurality of adjacent output signals having the same value.

Claim 28

An image reproducing system comprising: a) a scanning means for reading input image data corresponding to the image to be reproduced; b) a screening device comprising: memory means for storing image data representative of sequences of pluralities of input points and which contain information used to direct a marking device to mark or not mark indicia on a medium, and means for generating signals allocating the marking and not marking of the indicia on the medium based on a value of a current input point in a sequence of input points, a previous output signal corresponding to a previous input point in the sequence and an error representing a difference between the previous input points and the corresponding output signals scaled relative to a maximum gray scale, the error influencing output signals for subsequent input points in the sequence; and c) a marking device to receive the output signals from the screening device, whereby the marking device marks variable size dots comprising indicia corresponding to said output signals, wherein said variable size dots are determined from a recursive relationship between said current input point in a sequence of input points, said previous output signal corresponding to a previous input point in the sequence and said error representing a difference between the previous input points and the corresponding output signals; and means responsive to a prior output signal corresponding to indicia of said halftone screen prior to said present output signal, and coupled to said means for generating signals to tend make said present output signal the same value as a prior adjacent output signal, thereby forming a variable size dot comprising a plurality of adjacent output signals having the same value.