US5818604A
Expired / Lapsed
US
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High precision gradation compensation for stochastic screening
Assignee: Agfa NV
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Filing: 1996-05-02
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Granted: 1998-10-06
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Expires: 2016-05-02
Abstract
Abstract A halftone screen and method for generating halftones representing a continuous tone image, wherein the number of halftone dots per unit area varies non-proportionally with the tone values utilized as inputs to the screening process. The method incorporates an implicit gradation compensation as part of the frequency modulation halftoning itself to correct for the additional tone gain due to recording, plate processing and/or printing, as well as aesthetic corrections. This implicit compensation has the advantage that no external compensation is required, thereby maintaining the number of tone values which can be rendered on a digital system. Finally, the implicit gradation compensation enables the combination of page elements rendered according to either "conventional" or "frequency-modulated" halftoning techniques with appropriate tone-matching.
Inventors
- 👤 Paul A. Delabastita
- 👤 Frank A. Deschuytere
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 14:46
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/407; H04N1/405; H04N1/4051
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
79 words
A method for producing a FREQUENCY-MODULATED HALFTONE SCREEN of a source image comprising at least one pixel, said method comprising the steps of: (A) generating at least one NON-HALFTONE VALUE; (B) altering said at least one NON-HALFTONE VALUE at a higher tone resolution than the tone resolution of said at least one pixel comprising said source image; and, (C) utilizing said at least one altered NON-HALFTONE VALUE to produce at least one halftone value for the FREQUENCY-MODULATED HALFTONE SCREEN.
Claim 2
Independent Claim
79 words
A method for producing a FREQUENCY-MODULATED HALFTONE SCREEN of a source image comprising at least one pixel, said method comprising the steps of: (A) generating at least one NON-HALFTONE VALUE; (B) altering said at least one NON-HALFTONE VALUE at a higher tone resolution than the tone resolution of said at least one pixel comprising said source image; and, (C) utilizing said at least one altered NON-HALFTONE VALUE to produce at least one halftone value for the FREQUENCY-MODULATED HALFTONE SCREEN.
Claim 3
Independent Claim
81 words
A method for producing a frequency-modulated halftone screen of a source image comprising a plurality of pixels, said method comprising the steps of: (A) generating a plurality of NON-HALFTONE VALUES; (B) altering at least some of said plurality of NON-HALFTONE VALUES at a higher tone resolution than the tone resolution of pixels of said plurality of pixels comprised in said source image; and, (C) utilizing said at least some altered NON-HALFTONE VALUES to produce halftone values for the FREQUENCY-MODULATED HALFTONE SCREEN.
Claim 4
Independent Claim
81 words
A method for producing a frequency-modulated halftone screen of a source image comprising a plurality of pixels, said method comprising the steps of: (A) generating a plurality of NON-HALFTONE VALUES; (B) altering at least some of said plurality of NON-HALFTONE VALUES at a higher tone resolution than the tone resolution of pixels of said plurality of pixels comprised in said source image; and, (C) utilizing said at least some altered NON-HALFTONE VALUES to produce halftone values for the FREQUENCY-MODULATED HALFTONE SCREEN.
Claim 5
Independent Claim
147 words
A method for rendering pixel values in a FREQUENCY-MODULATED HALFTONE SCREEN, said method comprising the steps of: (A) generating at least one non-periodic screen function S, having screen function values; (B) altering at least one value of said at least one non-periodic screen function S to produce a corresponding at least one non-periodic screen S'; (C) utilizing said corresponding at least one non-periodic function S' and at least some of the pixel values to produce halftone values for the FREQUENCY-MODULATED HALFTONE SCREEN; (D) generating another non-periodic screen function S having screen function values; (E) altering at least one value of said another non-periodic screen function S to produce a corresponding another non-periodic screen function S'; and, (F) utilizing said corresponding another non-periodic screen function S' and pixel values other than said at least some of the pixel values to produce halftone values for the FREQUENCY-MODULATED HALFTONE SCREEN.
Claim 6
Independent Claim
147 words
A method for rendering pixel values in a FREQUENCY-MODULATED HALFTONE SCREEN, said method comprising the steps of: (A) generating at least one non-periodic screen function S, having screen function values; (B) altering at least one value of said at least one non-periodic screen function S to produce a corresponding at least one non-periodic screen S'; (C) utilizing said corresponding at least one non-periodic function S' and at least some of the pixel values to produce halftone values for the FREQUENCY-MODULATED HALFTONE SCREEN; (D) generating another non-periodic screen function S having screen function values; (E) altering at least one value of said another non-periodic screen function S to produce a corresponding another non-periodic screen function S'; and, (F) utilizing said corresponding another non-periodic screen function S' and pixel values other than said at least some of the pixel values to produce halftone values for the FREQUENCY-MODULATED HALFTONE SCREEN.
Claim 7
Independent Claim
93 words
A method for rendering pixel values in a FREQUENCY-MODULATED HALFTONE SCREEN, said method comprising the steps of: (A) generating a non-periodic screen function S having screen function values at a first tone resolution; (B) altering at least one value of said non-periodic screen function S to produce a non-periodic screen function S'; (C) changing said non-periodic screen function S' to a second tone resolution that is coarser than the first tone resolution; and, (D) utilizing said changed non-periodic function S' and said pixel values to produce halftone values for said FREQUENCY-MODULATED HALFTONE SCREEN.
Claim 8
Independent Claim
93 words
A method for rendering pixel values in a FREQUENCY-MODULATED HALFTONE SCREEN, said method comprising the steps of: (A) generating a non-periodic screen function S having screen function values at a first tone resolution; (B) altering at least one value of said non-periodic screen function S to produce a non-periodic screen function S'; (C) changing said non-periodic screen function S' to a second tone resolution that is coarser than the first tone resolution; and, (D) utilizing said changed non-periodic function S' and said pixel values to produce halftone values for said FREQUENCY-MODULATED HALFTONE SCREEN.
Claim 9
Independent Claim
128 words
A method for gradation control of the rendering of pixel values in a FREQUENCY-MODULATED HALFTONE SCREEN, said method comprising the steps of: (A) determining a tone gradation function G desired to alter the gradation in the pixel values to be rendered; (B) using said tone gradation function to obtain an inverse gradation function G -1 ; (C) generating a non-periodic function S having a first tone resolution; (D) obtaining an altered screen function S' from said non-periodic screen function S and said inverse gradation function G -1 ; (E) quantizing said altered screen function S' to a second tone resolution which is coarser than said first resolution; and, (F) utilizing said quantized screen function S' and said pixel values to produce halftone values for said FREQUENCY-MODULATED HALFTONE SCREEN.
Claim 10
Independent Claim
128 words
A method for gradation control of the rendering of pixel values in a FREQUENCY-MODULATED HALFTONE SCREEN, said method comprising the steps of: (A) determining a tone gradation function G desired to alter the gradation in the pixel values to be rendered; (B) using said tone gradation function to obtain an inverse gradation function G -1 ; (C) generating a non-periodic function S having a first tone resolution; (D) obtaining an altered screen function S' from said non-periodic screen function S and said inverse gradation function G -1 ; (E) quantizing said altered screen function S' to a second tone resolution which is coarser than said first resolution; and, (F) utilizing said quantized screen function S' and said pixel values to produce halftone values for said FREQUENCY-MODULATED HALFTONE SCREEN.
Claim 11
Dependent Claim
13 words
The method of claim 5 wherein said alteration compensates for press gain effects.
Claim 12
Dependent Claim
13 words
The method of claim 5 wherein said alteration compensates for recorder gain effects.
Claim 13
Dependent Claim
19 words
The method of claim 5 wherein said alteration compensates for the combined effects of press gain and recorder gain.
Claim 14
Independent Claim
14 words
The method of 5 wherein said alteration adjusts the tonal characteristics for aesthetic purposes.
Claim 15
Independent Claim
14 words
The method of 5 wherein said alteration adjusts the tonal characteristics for aesthetic purposes.
Claim 16
Independent Claim
20 words
The method of claims 1, 2, 3, 4, 5, 6, 7, 8 or 9 wherein said halftone values are bilevel.
Claim 17
Independent Claim
20 words
The method of claims 1, 2, 3, 4, 5, 6, 7, 8 or 9 wherein said halftone values are multi-level.
Claim 18
Dependent Claim
23 words
A photosensitive material comprising a halftone screen produced by the method of claims 1, 2, 3, 4, 5, 6, 7, 8 or 10.
Claim 19
Independent Claim
19 words
The method of claims 1, 2, 3 or 4 wherein said alteration compensates for the effects of press gain.
Claim 20
Independent Claim
19 words
The method of claims 1, 2, 3 or 4 wherein said alteration compensates for the effects of recorder gain.
Claim 21
Independent Claim
23 words
The method of claims 1, 2, 3 or 4 wherein said alteration compensates for the combined effects of press gain and recorder gain.
Claim 22
Independent Claim
19 words
The method of claims 1, 2, 3 or 4 wherein said alteration adjusts the tonal characteristics for aesthetic purposes.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-10-05 | 2002-04-06 | 2002-10-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-10-05 | 2006-04-06 | 2006-10-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-10-05 | 2010-04-06 | 2010-10-06 | $7700.00 | Window Closed / Lapsed |