US 5,331,430 A · Electronic high-fidelity screenless conversion system

Abstract

A system is disclosed for converting a continuous tone value to an output value having a first level or a second level. A first error magnitude is generated based upon continuous tone values already converted, continuous tone values not yet converted and an output value having the first level assumed for the continuous tone value undergoing conversion. A second error magnitude is similarly generated except that an output value having the second level is assumed for the continuous tone value undergoing conversion. If the first error magnitude is less than the second error magnitude, then the continuous tone value undergoing conversion is converted to the output value having the first level and, otherwise, the continuous tone value undergoing conversion is converted to the output value having the second level. The error corresponding to the converted lineary value is diffused in a predetermined manner to neighboring continuous tone values which have not yet been converted.

Claims60

Dependent claims

A system for converting input values into output values, each of said input values having one of at least M possible levels and each of said output values having one of N possible levels, where M is greater than N, said system converting, in turn, each of said input values into a corresponding output value so that, at a given instant in time, an input value undergoing conversion has before it previously converted input values and after it input values yet to be converted, said system comprising:

error generating means for generating at least first and second errors for said input value undergoing conversion, said first error being based upon an output value corresponding to a previously converted input value, based upon an output value estimated from a corresponding input value yet to be converted, and based upon an output value having a first level assumed for said input value undergoing conversion, and said second error being based upon an output value corresponding to a previously converted input value, based upon an output value estimated from a corresponding input value yet to be converted, and based upon an output value having a second level assumed for said input value undergoing conversion;
output value setting means for setting said input value undergoing conversion to an output value having said first level if the absolute value of said first error is less than the absolute value of said second error or to an output value having said second level if the absolute value of said first error is greater than the absolute value of said second error;
and,
diffusing means for diffusing, to a selected number of said input values yet to be converted, said first error if said input value undergoing conversion is set to said output value having said first level or said second error if said input value undergoing conversion is set to said output value having said second level.

1 more element

A system for converting continuous tone values into corresponding output values, said system converting, in turn, each of said continuous tone values to a corresponding output value so that, at a given instant in time, a continuous tone value undergoing conversion has before it previously converted continuous tone values and after it continuous tone values yet to be converted, said system comprising:

error generating means for generating first and second errors for said continuous tone value undergoing conversion, said first error being based upon a first set of output values multiplied by a first set of corresponding filter values wherein each output value of said first set of output values corresponds to a continuous tone value in a first set of previously converted continuous tone values, (b) a second set of output values multiplied by a second set of corresponding filter values wherein each output value of said second set of output values is predicted from a corresponding continuous tone value in a second set of continuous tone values yet to be converted, and (c) an output value having an assumed first level multiplied by a corresponding filter value, and said second error being based upon (a) said first set of output values multiplied by said first set of corresponding filter values, (b) said second set of output values multiplied by said second set of corresponding filter values, and (c) an output value having an assumed second level multiplied by said corresponding filter value;
output value setting means for setting said continuous tone value undergoing conversion to said output value having said first level if the absolute value of said first error is less than the absolute value of said second error or to said output value having said second level if the absolute value of said first error is greater than the absolute value of said second error;
and,
diffusing means for diffusing, to a predetermined number of said continuous tone values yet to be converted, said first error if said continuous tone value undergoing conversion is set to said output value having said first level or said second error if said continuous tone value undergoing conversion is set to said output value having said second level.

1 more element

A method of converting input values to corresponding output values, each of said input values having one of at least M possible levels and each of said output values having one of N possible levels, where M is greater than N, said method comprising the following steps:

(a) multiplying each output value of a first set of output values by a corresponding filter value from a first set of filter values wherein each output value of said first set of output values corresponds to an input value in a first set of previously converted input values;
(b) predicting a second set of output values wherein each output value of said second set of output values corresponds to an input value in a second set of input values yet to be converted;
(c) multiplying each output value of said predicted second set of said output values by a corresponding filter value from a second set of filter values;
(d) multiplying a filter value corresponding to an input value undergoing conversion by an output value having an assumed first level;
(e) multiplying said filter value corresponding to said input value undergoing conversion by an output value having an assumed second level;
(f) providing a first error by subtracting the results of steps (a), (c) and (d) from said input value undergoing conversion;
(g) providing a second error by subtracting the results of steps (a), (c) and (e) from said input value undergoing conversion;
(h) converting said input value undergoing conversion to an output value having said first level if the absolute value of said first error is smaller than the absolute value of said second error;
(i) converting said input value undergoing conversion to an output value having said second level if the absolute value of said first error is greater than the absolute value of said second error;
(j) diffusing, to a predetermined number of said input values yet to be converted, said first error if said input value undergoing conversion is converted to said output value having said first level or said second error if said input value undergoing conversion is converted to said output value having said second level;
and
(k) repeating steps (a)-(j) for each of the input values yet to be converted.

9 more elements

A method of converting continuous tone values to corresponding output values such tat, at a given time during conversion, said continuous tone values include continuous tone values already converted, a continuous tone value undergoing conversion, and continuous tone values yet to be converted, said method comprising the following steps:

(a) deriving a first error based upon an output value corresponding to a continuous tone value already converted, based upon an output value predicted rom a continuous toe value yet to be converted, and based upon an output value having a first level assumed for said continuous tone value undergoing conversion;
(b) deriving a second error based upon said output value corresponding to said continuous tone value already converted, based upon said output value predicted form said at least on continuous tone value yet to be converted, and based upon an output value having a second level assumed for said continuous tone value undergoing conversion;
(c) converting said continuous tone value undergoing conversion to said output value having said first level if the absolute value of said first error is smaller than the absolute value of said second error or to said output value having said second level if the absolute value of said first error is greater than the absolute value of said second error.
(d) diffusing, to a predetermined number of said continuous tone values yet to be converted, said first error if said continuous tone value undergoing conversion is converted to said output value having said first level or said second error if said continuous tone value undergoing conversion is converted to said output value having said second level;
(e) repeating steps (a)-(d) for each of said continuous tone values yet to be converted.

2 more elements

A system for plotting dots on a film in response to continuous tone values generated by scanning an image to be reproduced, said system comprising:

screenless conversion means for converting, said continuous tone values to corresponding output values wherein a continuous tone value undergoing conversion is converted by the use of predicted output values and converted output values in a symmetrical region surrounding said continuous tone value undergoing conversion;
and,
film plotting means for plotting dots onto a film in response to said output values, said dots representing an image to be reproduced.

A system for forming printing plates directly from output values converted from continuous tone values generated by scanning an image to be reproduced, said system comprising:

screenless conversion means for converting each of said continuous tone values to a corresponding output value by (a) determining first and second errors based upon output values having first and second levels respectively assumed for a continuous tone value undergoing conversion, (b) converting said continuous tone value undergoing conversion to an output value having said first level fi the absolute value of said first error is less than the absolute value of said second error or to an output value having said second level if the absolute value of said first error is greater than the absolute value of said second error, and (c) diffusing, to a predetermined number of continuous tone values yet to be converted, said first error if said continuous tone value undergoing conversion is converted to said output value having said first level or said second error if said continuous tone value undergoing conversion is converted to said output value having said second level;
and
plate forming means for forming said printing plates directly from said output values.

A screenless conversion method of converting regularly scanned data into output values comprising the following steps:

(a) descreening said regularly screened data into continuous tone values;
(b) determining, for a continuous tone value undergoing conversion, first and second errors based upon output values having corresponding first and second levels assumed for said continuous tone value undergoing conversion;
(c) converting said continuous tone value undergoing conversion to an output value having said first level if the absolute value of said first error is less than the absolute value of said second error or to an output value having said second level if the absolute value of said first error is greater than the absolute value of said second error;
and,
(d) diffusing, to a predetermined number of continuous tone values yet to be converted, said first error if said continuous tone value undergoing conversion is converted to said output value having said first level or said second error if said continuous tone value undergoing conversion is converted to said output value having said second level.

2 more elements

A reproduction system comprising:

input means for providing continuous tone values based upon an original to be reproduced;
screenless conversion means for converting each of said continuous tone values into a corresponding output value by (a) determining first and second errors based upon output values having corresponding first and second levels assumed for a continuous tone value undergoing conversion, (b) converting said continuous tone value undergoing conversion to an output value having said first level if the absolute value of said first error is less than the absolute value of said second error or to an output value having said second level if the absolute value of said first error is greater than the absolute value of said second error, and (c) diffusing, to a predetermined number of continuous tone values yet to be converted, said first error if said continuous tone value undergoing conversion is converted to said output value having said first level or said second error if said continuous tone value undergoing conversion is converted to said output value having said second level;
and
proofing means for proofing said output values to ensure that said output values represent a desired reproduction of said original.

1 more element

Dependencies are inferred from the claim text.

Electronic high-fidelity screenless conversion system

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Electronic high-fidelity screenless conversion system

Life of this patent

Abstract

Claims60