Error diffusion pattern shifting reduction through programmable threshold perturbation

Claim 1

A system for processing image data having a multi-level grey signal having a first number of grey levels, comprising: threshold means for generating a threshold value; conversion means for generating an output having a second number of grey levels based on a relationship between the threshold value and a modified multi-level grey signal, the second number of grey levels being less than the first number of grey levels, and for generating an error corresponding to the relationship between the threshold value and the modified multi-level grey signal; error diffusion means for adding an error value, corresponding to a predetermined number of errors previously generated by said conversion means, to the multi-level grey signal to generate the modified multi-level grey signal; and perturbing means for perturbing, according to a grey level of the multi-level grey signal, the relationship between the threshold value and the modified multi-level grey signal by changing the threshold value by a predetermined value, said predetermined value is one of a plurality of values forming a predetermined pattern associated with a particular grey level, said predetermined value being added to the threshold value is determined from a pixel location and grey level of the multi-level grey signal, prior to being modified, being processed by said conversion means, thereby effecting the output and the error from said conversion means.

Claim 2

A system for processing image data having a multi-level grey signal having a first number of grey levels, comprising: threshold means for generating a threshold value; conversion means for generating an output having a second number of grey levels based on a relationship between the threshold value and a modified multi-level grey signal, the second number of grey levels being less than the first number of grey levels, and for generating an error corresponding to the relationship between the threshold value and the modified multi-level grey signal; error diffusion means for adding an error value, corresponding to a predetermined number of errors previously generated by said conversion means, to the multi-level grey signal to generate the modified multi-level grey signal; and perturbing means for perturbing, according to a grey level of the multi-level grey signal, the relationship between the threshold value and the modified multi-level grey signal by changing the threshold value by a predetermined value, said predetermined value is one of a plurality of values forming a predetermined pattern associated with a particular grey level, said predetermined value being added to the threshold value is determined from a pixel location and grey level of the multi-level grey signal, prior to being modified, being processed by said conversion means, thereby effecting the output and the error from said conversion means.

Claim 9

A system for processing image data having a multi-level grey signal having a first number of grey levels, comprising: threshold means for generating a threshold value; conversion means for generating an output having a second number of grey levels based on a relationship between the threshold value and a modified multi-level grey signal, the second number of grey levels being less than the first number of grey levels, and for generating an error corresponding to the relationship between the threshold value and the modified multi-level grey signal; error diffusion means for adding an error value, corresponding to a predetermined number of errors previously generated by said conversion means, to the multi-level grey signal to generate the modified multi-level grey signal: and perturbing means for perturbing, according to a grey level of the multi-level grey signal, the relationship between the threshold value and the modified multi-level grey signal by changing the modified multi-level grey signal by a predetermined value, said predetermined value is one of a plurality of values forming a predetermined pattern associated with a particular grey level, said predetermined value being added to the modified multi-level grey signal is determined from a pixel location and grey level of the multi-level grey signal, prior to being modified, being processed by said conversion means, thereby effecting the output and the error from said conversion means.

Claim 10

A system for processing image data having a multi-level grey signal having a first number of grey levels, comprising: threshold means for generating a threshold value; conversion means for generating an output having a second number of grey levels based on a relationship between the threshold value and a modified multi-level grey signal, the second number of grey levels being less than the first number of grey levels, and for generating an error corresponding to the relationship between the threshold value and the modified multi-level grey signal; error diffusion means for adding an error value, corresponding to a predetermined number of errors previously generated by said conversion means, to the multi-level grey signal to generate the modified multi-level grey signal: and perturbing means for perturbing, according to a grey level of the multi-level grey signal, the relationship between the threshold value and the modified multi-level grey signal by changing the modified multi-level grey signal by a predetermined value, said predetermined value is one of a plurality of values forming a predetermined pattern associated with a particular grey level, said predetermined value being added to the modified multi-level grey signal is determined from a pixel location and grey level of the multi-level grey signal, prior to being modified, being processed by said conversion means, thereby effecting the output and the error from said conversion means.

Claim 14

A method of processing image data having a multi-level grey signal having a first number of grey levels, comprising the steps of: (a) generating a threshold value; (b) generating an output having a second number of grey levels based on a relationship between the threshold value and a modified multi-level grey signal, the second number of grey levels being less than the first number of grey levels; (c) generating an error corresponding to the relationship between the threshold value and the modified multi-level grey signal; (d) adding an error value, corresponding to a predetermined number of errors previously generated by said step (c), to the multi-level grey signal to generate the modified multi-level grey signal: (e) perturbing according to a grey level of the multi-level grey signal the relationship, by a predetermined value, between the threshold value and the modified multi-level grey, thereby effecting the output of said step (b) and the error of said step (c); (f) selecting a predetermined value from one of a plurality of values forming a predetermined pattern associated with a particular grey level; and (g) determining the predetermined value from a pixel location and grey level of the multi-level grey signal being processed.

Claim 15

A method of processing image data having a multi-level grey signal having a first number of grey levels, comprising the steps of: (a) generating a threshold value; (b) generating an output having a second number of grey levels based on a relationship between the threshold value and a modified multi-level grey signal, the second number of grey levels being less than the first number of grey levels; (c) generating an error corresponding to the relationship between the threshold value and the modified multi-level grey signal; (d) adding an error value, corresponding to a predetermined number of errors previously generated by said step (c), to the multi-level grey signal to generate the modified multi-level grey signal: (e) perturbing according to a grey level of the multi-level grey signal the relationship, by a predetermined value, between the threshold value and the modified multi-level grey, thereby effecting the output of said step (b) and the error of said step (c); (f) selecting a predetermined value from one of a plurality of values forming a predetermined pattern associated with a particular grey level; and (g) determining the predetermined value from a pixel location and grey level of the multi-level grey signal being processed.

Claim 18

A system for eliminating pattern shifting artifacts in a printed image, comprising: image means for generating image data having a multi-level grey signal; programmable multi-level grey signal modifying means for modifying an error diffused multi-level grey signal by a predetermined value according to the grey level of the multi-level grey signal to generate a modified multi-level grey signal; binary means for outputting a binary pixel value according to a relationship between the modified multi-level grey signal from said programmable multi-level grey signal modifying means and a threshold value, for generating an error corresponding to the relationship, and for diffusing the error to neighboring pixels; and error diffusion means for adding an error value, corresponding to a predetermined number of errors previously generated by said binary means, to the multi-level grey signal to generate the error diffused multi-level grey signal.

Claim 19

A system for eliminating pattern shifting artifacts in a printed image, comprising: image means for generating image data having a multi-level grey signal; programmable multi-level grey signal modifying means for modifying an error diffused multi-level grey signal by a predetermined value according to the grey level of the multi-level grey signal to generate a modified multi-level grey signal; binary means for outputting a binary pixel value according to a relationship between the modified multi-level grey signal from said programmable multi-level grey signal modifying means and a threshold value, for generating an error corresponding to the relationship, and for diffusing the error to neighboring pixels; and error diffusion means for adding an error value, corresponding to a predetermined number of errors previously generated by said binary means, to the multi-level grey signal to generate the error diffused multi-level grey signal.

Claim 20

A system for processing image data having a multi-level grey signal having a first number of grey levels, comprising: threshold means for generating a threshold value; conversion means for generating an output having a second number of grey levels based on a relationship between a modified threshold value and the multi-level grey signal, the second number of grey levels being less than the first number of grey levels, and for generating an error corresponding to the relationship between the modified threshold value and the multi-level grey signal; error diffusion means for adding an error value, corresponding to a predetermined number of errors previously generated by said conversion means, to the threshold value to generate the modified threshold value; and perturbing means for perturbing, according to a grey level of the multi-level grey signal, the relationship between the modified threshold value and the multi-level grey signal by changing the modified threshold value by a predetermined value, said predetermined value is one of a plurality of values forming a predetermined pattern associated with a particular grey level, said predetermined value being added to the modified threshold value is determined from a pixel location and grey level of the multi-level grey signal being processed by said conversion means, thereby effecting the output and the error from said conversion means.

Claim 21

A system for processing image data having a multi-level grey signal having a first number of grey levels, comprising: threshold means for generating a threshold value; conversion means for generating an output having a second number of grey levels based on a relationship between a modified threshold value and the multi-level grey signal, the second number of grey levels being less than the first number of grey levels, and for generating an error corresponding to the relationship between the modified threshold value and the multi-level grey signal; error diffusion means for adding an error value, corresponding to a predetermined number of errors previously generated by said conversion means, to the threshold value to generate the modified threshold value; and perturbing means for perturbing, according to a grey level of the multi-level grey signal, the relationship between the modified threshold value and the multi-level grey signal by changing the modified threshold value by a predetermined value, said predetermined value is one of a plurality of values forming a predetermined pattern associated with a particular grey level, said predetermined value being added to the modified threshold value is determined from a pixel location and grey level of the multi-level grey signal being processed by said conversion means, thereby effecting the output and the error from said conversion means.

Claim 22

A system for processing image data having a multi-level grey signal having a first number of grey levels, comprising: threshold means for generating a threshold value; conversion means for generating an output having a second number of grey levels based on a relationship between a modified threshold value and the multi-level grey signal, the second number of grey levels being less than the first number of grey levels, and for generating an error corresponding to the relationship between the modified threshold value and the multi-level grey signal; error diffusion means for adding an error value, corresponding to a predetermined number of errors previously generated by said conversion means, to the threshold value to generate the modified threshold value; and perturbing means for perturbing, according to a grey level of the multi-level grey signal, the relationship between the modified threshold value and the multi-level grey signal by changing the multi-level grey signal by a predetermined value, said predetermined value is one of a plurality of values forming a predetermined pattern associated with a particular grey level, said predetermined value being added to the multi-level grey signal is determined from a pixel location and grey level of the multi-level grey signal being processed by said conversion means, thereby effecting the output and the error from said conversion means.

Claim 23

A system for processing image data having a multi-level grey signal having a first number of grey levels, comprising: threshold means for generating a threshold value; conversion means for generating an output having a second number of grey levels based on a relationship between a modified threshold value and the multi-level grey signal, the second number of grey levels being less than the first number of grey levels, and for generating an error corresponding to the relationship between the modified threshold value and the multi-level grey signal; error diffusion means for adding an error value, corresponding to a predetermined number of errors previously generated by said conversion means, to the threshold value to generate the modified threshold value; and perturbing means for perturbing, according to a grey level of the multi-level grey signal, the relationship between the modified threshold value and the multi-level grey signal by changing the multi-level grey signal by a predetermined value, said predetermined value is one of a plurality of values forming a predetermined pattern associated with a particular grey level, said predetermined value being added to the multi-level grey signal is determined from a pixel location and grey level of the multi-level grey signal being processed by said conversion means, thereby effecting the output and the error from said conversion means.

Claim 24

A system for processing image data having a multi-level grey signal having a first number of grey levels, comprising: threshold means for generating a threshold value; conversion means for generating an output having a second number of grey levels based on a relationship between the threshold value and a modified multi-level grey signal, the second number of grey levels being less than the first number of grey levels, and for generating an error corresponding to the relationship between the threshold value and the modified multi-level grey signal; error diffusion means for adding an error value, corresponding to a predetermined number of errors previously generated by said conversion means, to the multi-level grey signal to generate the modified multi-level grey signal; and perturbing means for perturbing, according to a grey level of the multi-level grey signal, the relationship between the threshold value and the modified multi-level grey signal by changing the threshold value by a weighted random noise signal; said perturbing means including, a random noise generator to produce random noise, a weighting value generator to produce a predetermined value, said predetermined value being one of a plurality of values forming a predetermined pattern associated with a particular grey level, said predetermined value being determined from a pixel location and grey level of the multi-level grey signal being processed by said conversion means, and a multiplier to generate said weighted random noise signal from said random noise and said predetermined value.

Claim 25

A system for processing image data having a multi-level grey signal having a first number of grey levels, comprising: threshold means for generating a threshold value; conversion means for generating an output having a second number of grey levels based on a relationship between the threshold value and a modified multi-level grey signal, the second number of grey levels being less than the first number of grey levels, and for generating an error corresponding to the relationship between the threshold value and the modified multi-level grey signal; error diffusion means for adding an error value, corresponding to a predetermined number of errors previously generated by said conversion means, to the multi-level grey signal to generate the modified multi-level grey signal; and perturbing means for perturbing, according to a grey level of the multi-level grey signal, the relationship between the threshold value and the modified multi-level grey signal by changing the threshold value by a weighted random noise signal; said perturbing means including, a random noise generator to produce random noise, a weighting value generator to produce a predetermined value, said predetermined value being one of a plurality of values forming a predetermined pattern associated with a particular grey level, said predetermined value being determined from a pixel location and grey level of the multi-level grey signal being processed by said conversion means, and a multiplier to generate said weighted random noise signal from said random noise and said predetermined value.

Claim 26

A system for processing image data having a multi-level grey signal having a first number of grey levels, comprising: threshold means for generating a threshold value; conversion means for generating an output having a second number of grey levels based on a relationship between the threshold value and a modified multi-level grey signal, the second number of grey levels being less than the first number of grey levels, and for generating an error corresponding to the relationship between the threshold value and the modified multi-level grey signal; error diffusion means for adding an error value, corresponding to a predetermined number of errors previously generated by said conversion means, to the multi-level grey signal to generate the modified multi-level grey signal; and perturbing means for perturbing, according to a grey level of the multi-level grey signal, the relationship between the threshold value and the modified multi-level grey signal by changing the threshold value by a weighted random noise signal; said perturbing means including, a random noise generator to produce random noise, a weighting value generator to produce a predetermined value, said predetermined value being one of a plurality of values forming a predetermined pattern associated with a particular grey level, said predetermined value being determined from a pixel location and grey level of the multi-level grey signal being processed by said conversion means, and a multiplier to generate said weighted random noise signal from said random noise and said predetermined value.

Claim 27

A system for processing image data having a multi-level grey signal having a first number of grey levels, comprising: threshold means for generating a threshold value; conversion means for generating an output having a second number of grey levels based on a relationship between the threshold value and a modified multi-level grey signal, the second number of grey levels being less than the first number of grey levels, and for generating an error corresponding to the relationship between the threshold value and the modified multi-level grey signal; error diffusion means for adding an error value, corresponding to a predetermined number of errors previously generated by said conversion means, to the multi-level grey signal to generate the modified multi-level grey signal; and perturbing means for perturbing, according to a grey level of the multi-level grey signal, the relationship between the threshold value and the modified multi-level grey signal by changing the threshold value by a weighted random noise signal; said perturbing means including, a random noise generator to produce random noise, a weighting value generator to produce a predetermined value, said predetermined value being one of a plurality of values forming a predetermined pattern associated with a particular grey level, said predetermined value being determined from a pixel location and grey level of the multi-level grey signal being processed by said conversion means, and a multiplier to generate said weighted random noise signal from said random noise and said predetermined value.

Claim 28

A system for processing image data having a multi-level grey signal having a first number of grey levels, comprising: threshold means for generating a threshold value; conversion means for generating an output having a second number of grey levels based on a relationship between a modified threshold value and the multi-level grey signal, the second number of grey levels being less than the first number of grey levels, and for generating an error corresponding to the relationship between the modified threshold value and the multi-level grey signal; error diffusion means for adding an error value, corresponding to a predetermined number of errors previously generated by said conversion means, to the threshold value to generate the modified threshold value; and perturbing means for perturbing, according to a grey level of the multi-level grey signal, the relationship between the modified threshold value and the multi-level grey signal by changing the multi-level grey signal by a weighted random noise signal; said perturbing means including, a random noise generator to produce random noise, a weighting value generator to produce a predetermined value, said predetermined value being one of a plurality of values forming a predetermined pattern associated with a particular grey level, said predetermined value being determined from a pixel location and grey level of the multi-level grey signal being processed by said conversion means, and a multiplier to generate said weighted random noise signal from said random noise and said predetermined value.

Claim 29

A system for processing image data having a multi-level grey signal having a first number of grey levels, comprising: threshold means for generating a threshold value; conversion means for generating an output having a second number of grey levels based on a relationship between a modified threshold value and the multi-level grey signal, the second number of grey levels being less than the first number of grey levels, and for generating an error corresponding to the relationship between the modified threshold value and the multi-level grey signal; error diffusion means for adding an error value, corresponding to a predetermined number of errors previously generated by said conversion means, to the threshold value to generate the modified threshold value; and perturbing means for perturbing, according to a grey level of the multi-level grey signal, the relationship between the modified threshold value and the multi-level grey signal by changing the multi-level grey signal by a weighted random noise signal; said perturbing means including, a random noise generator to produce random noise, a weighting value generator to produce a predetermined value, said predetermined value being one of a plurality of values forming a predetermined pattern associated with a particular grey level, said predetermined value being determined from a pixel location and grey level of the multi-level grey signal being processed by said conversion means, and a multiplier to generate said weighted random noise signal from said random noise and said predetermined value.

Claim 30

A system for processing image data having a multi-level grey signal having a first number of grey levels, comprising: threshold means for generating a threshold value; conversion means for generating an output having a second number of grey levels based on a relationship between a modified threshold value and the multi-level grey signal, the second number of grey levels being less than the first number of grey levels, and for generating an error corresponding to the relationship between the modified threshold value and the multi-level grey signal; error diffusion means for adding an error value, corresponding to a predetermined number of errors previously generated by said conversion means, to the threshold value to generate the modified threshold value; and perturbing means for perturbing, according to a grey level of the multi-level grey signal, the relationship between the threshold value and the modified multi-level grey signal by changing the modified threshold value by a weighted random noise signal; said perturbing means including, a random noise generator to produce random noise, a weighting value generator to produce a predetermined value, said predetermined value being one of a plurality of values forming a predetermined pattern associated with a particular grey level, said predetermined value being determined from a pixel location and grey level of the multi-level grey signal being processed by said conversion means, and a multiplier to generate said weighted random noise signal from said random noise and said predetermined value.

Claim 31

A system for processing image data having a multi-level grey signal having a first number of grey levels, comprising: threshold means for generating a threshold value; conversion means for generating an output having a second number of grey levels based on a relationship between a modified threshold value and the multi-level grey signal, the second number of grey levels being less than the first number of grey levels, and for generating an error corresponding to the relationship between the modified threshold value and the multi-level grey signal; error diffusion means for adding an error value, corresponding to a predetermined number of errors previously generated by said conversion means, to the threshold value to generate the modified threshold value; and perturbing means for perturbing, according to a grey level of the multi-level grey signal, the relationship between the threshold value and the modified multi-level grey signal by changing the modified threshold value by a weighted random noise signal; said perturbing means including, a random noise generator to produce random noise, a weighting value generator to produce a predetermined value, said predetermined value being one of a plurality of values forming a predetermined pattern associated with a particular grey level, said predetermined value being determined from a pixel location and grey level of the multi-level grey signal being processed by said conversion means, and a multiplier to generate said weighted random noise signal from said random noise and said predetermined value.