Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
305 words
A method of producing dot-size corrected or modified halftone colour separations of an image for use in making a printing plate for printing reproductions of said image, which method comprises the steps of scanning each of said halftone separations separately to produce an electrical signal representing the same and digitizing said signals, storing said digitized values into a digital storage device, visualising from said digitized values on an image display device an image representative of at least one of said halftone separations, defining on said displayed image and by means of said stored values at least one area to be corrected, calculating by means of a microprocessor to which said stored values are applied at least one combination of halftone colour separation positives and/or negatives of said image that when exposed in overlaying relation on a photographic film yields a mask for isolating each such area to be corrected, visualising and evaluating the resultant mask alone or in superposition with at least one of said halftone separations on said image display device, redefining said area to be corrected in accordance with the result of said evaluation and recalculating a mask therefor by means of the stored data or by means of data pertaining to the previously calculated mask and visualising said recalculated mask for further evaluation as an acceptable final mask, photographically producing said recalculated mask for isolating said area to be corrected, determining the percentage dot size correction (increase or decrease) that is required, and exposing and processing light-sensitive print material to produce a print exhibiting the required percentage dot-size correction by subjecting said print material to a normal exposure for reproducing the corresponding original halftone separation plus an additional overexposure through the combination of said final mask and the corresponding halftone separation for a dose to give the determined change in dot size.
Claim 2
Independent Claim
305 words
A method of producing dot-size corrected or modified halftone colour separations of an image for use in making a printing plate for printing reproductions of said image, which method comprises the steps of scanning each of said halftone separations separately to produce an electrical signal representing the same and digitizing said signals, storing said digitized values into a digital storage device, visualising from said digitized values on an image display device an image representative of at least one of said halftone separations, defining on said displayed image and by means of said stored values at least one area to be corrected, calculating by means of a microprocessor to which said stored values are applied at least one combination of halftone colour separation positives and/or negatives of said image that when exposed in overlaying relation on a photographic film yields a mask for isolating each such area to be corrected, visualising and evaluating the resultant mask alone or in superposition with at least one of said halftone separations on said image display device, redefining said area to be corrected in accordance with the result of said evaluation and recalculating a mask therefor by means of the stored data or by means of data pertaining to the previously calculated mask and visualising said recalculated mask for further evaluation as an acceptable final mask, photographically producing said recalculated mask for isolating said area to be corrected, determining the percentage dot size correction (increase or decrease) that is required, and exposing and processing light-sensitive print material to produce a print exhibiting the required percentage dot-size correction by subjecting said print material to a normal exposure for reproducing the corresponding original halftone separation plus an additional overexposure through the combination of said final mask and the corresponding halftone separation for a dose to give the determined change in dot size.
Claim 3
Dependent Claim
21 words
Method according to claim 1 wherein said halftone colour separations of said image are scanned by means of a video camera.
Claim 4
Dependent Claim
48 words
Method according to claim 1 wherein said digitized data are converted into corresponding density values or percentage dot values or percentage dot values by means of a look up table representing a relation between output values of a video camera and corresponding density values or percentage dot values.
Claim 5
Dependent Claim
14 words
Method according to claim 1 wherein said image display device is a video monitor.
Claim 6
Dependent Claim
47 words
Method according to claim 1 wherein said area to be corrected is defined on the monitor screen by means of a cursor controlled by a pointing device, the corresponding stored data for said area being retrieved from said storage device and being used to calculate said mask.