US6778299B2
Expired / Lapsed
US
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Error diffusion with partial dots method and system
Assignee: Hewlett Packard Development Co LP
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Filing: 2001-03-09
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Granted: 2004-08-17
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Expires: 2021-03-09
Abstract
Abstract A method and system for halftoning images that uses error diffusion with partial dots is provided. First, an input picture element (input pixel) that has a picture level (e.g., gray level) is received. Next, a reproducible gray level is generated based on the gray level of an input pixel. Then, a corrected gray level is generated based on the gray level of an input pixel and an error amount (e.g., error propagated or diffused from adjacent areas or pixels). A determination is made whether the corrected gray level is in a predetermined relationship with a threshold. When the corrected gray level is in a predetermined relationship with the threshold, the reproducible gray level (i.e., partial dot size) is provided as output. When the corrected gray level is not in a predetermined relationship with the threshold, a zero value is provided as output. It is noted that the output gray level and the corrected gray level are provided to an error distribution module for calculating an error and for propagating or diffusing the error to future adjacent areas or pixels.
Inventors
- 👤 Qian Lin
- 👤 Daniel Tretter
- 👤 Jian Fan
- 👤 Clayton Brian Atkins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 14:09
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/405; H04N1/4051; H04N1/4052; H04N1/4053; G; G06; G06K; G06K15/00; G06K15/02; G06K15/10; G06K15/102; G06K15/105; G06K15/107; H04N1/40087
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
121 words
A method for halftoning a digital image having a plurality of input pixels comprising: receiving an input pixel at a dot size look-up table; generating a reproducible gray level based on a gray level of at least one input pixel using the dot size look-up table; generating a corrected gray level based on the gray level of at least one input pixel and an error amount; determining whether the corrected gray level is in a predetermined relationship with a threshold; when the corrected gray level is in a predetermined relationship with the threshold, providing the reproducible gray level as output; and when the corrected gray level is not in a predetermined relationship with the threshold, providing a zero value as output.
Claim 2
Independent Claim
121 words
A method for halftoning a digital image having a plurality of input pixels comprising: receiving an input pixel at a dot size look-up table; generating a reproducible gray level based on a gray level of at least one input pixel using the dot size look-up table; generating a corrected gray level based on the gray level of at least one input pixel and an error amount; determining whether the corrected gray level is in a predetermined relationship with a threshold; when the corrected gray level is in a predetermined relationship with the threshold, providing the reproducible gray level as output; and when the corrected gray level is not in a predetermined relationship with the threshold, providing a zero value as output.
Claim 3
Dependent Claim
47 words
The method of claim 1 further comprising the step of providing an error measure to an error distribution module; wherein the error measure is based on the output gray level and the corrected gray level; wherein the error distribution module propagates the error measure to future pixels.
Claim 4
Dependent Claim
48 words
The method of claim 1 further comprising the step of providing the output gray level and the corrected gray level to an error distribution module; determining the error measure based on the output gray level and the corrected gray level; and propagating the error measure to future pixels.
Claim 5
Dependent Claim
18 words
The method of claim 1 wherein the threshold is one of predetermined threshold and a randomly generated threshold.
Claim 6
Dependent Claim
16 words
The method of claim 4 wherein the predetermined threshold is generated by employing a halftone screen.
Claim 7
Dependent Claim
28 words
The method of claim 5 wherein the halftone screen is one of a blue noise halftone screen, a clustered dot halftone screen, and a green noise halftone screen.
Claim 8
Dependent Claim
35 words
The method of claim 1 wherein the step of determining whether the corrected gray level is in a predetermined relationship with a threshold includes: determining whether the corrected gray level is greater than the threshold.
Claim 9
Dependent Claim
44 words
The method of claim 1 wherein the threshold is generated by the following expression: t ( i,j )=0.3*(128 −t csd ( i,j ))+ p /2, where t csd (i,j) is a ColorSmooth dither matrix element, and where p is the reproducible gray level value.
Claim 10
Dependent Claim
35 words
The method of claim 1 wherein the reproducible gray levels are manifested as partial dots generated by using sub-pixel modulation in the highlight areas and transitioning into full dots in the mid-tone and shadow areas.
Claim 11
Dependent Claim
43 words
The method of claim 1 wherein the output pixel value z(i,j) is generated by the following expression: z(i,j)=p(i,j),if y(i,j)>t(i,j) 0, otherwise, where y(i,j) is the corrected gray level value, where p is the reproducible gray level value, and where t(i,j) is the threshold.
Claim 12
Dependent Claim
34 words
The method of claim 5 wherein the method is implemented in an ink-jet printing process; the method further comprising the step of: selecting a threshold array that is suitable for the ink-jet printing process.
Claim 13
Dependent Claim
34 words
The method of claim 5 wherein the method is implemented in an laser printing process; the method further comprising the step of: selecting a threshold array that is suitable for the laser printing process.
Claim 14
Independent Claim
117 words
A system for halftoning a digital image having a plurality of input pixels comprising: a dot size look-up table for receiving an input pixel and responsive thereto for generating a reproducible gray level based on a gray level of at least one input pixel; and a variable output thresholding module for receiving a corrected gray level and the reproducible gray level and determining whether the corrected gray level is in a predetermined relationship with a threshold, when the corrected gray level is in a predetermined relationship with the threshold, providing the reproducible gray level as output; and when the corrected gray level is not in a predetermined relationship with the threshold, providing a zero value as output.
Claim 15
Independent Claim
117 words
A system for halftoning a digital image having a plurality of input pixels comprising: a dot size look-up table for receiving an input pixel and responsive thereto for generating a reproducible gray level based on a gray level of at least one input pixel; and a variable output thresholding module for receiving a corrected gray level and the reproducible gray level and determining whether the corrected gray level is in a predetermined relationship with a threshold, when the corrected gray level is in a predetermined relationship with the threshold, providing the reproducible gray level as output; and when the corrected gray level is not in a predetermined relationship with the threshold, providing a zero value as output.
Claim 16
Dependent Claim
39 words
The system for halftoning a digital image having a plurality of input pixels of claim 13 further comprising: a correction module for receiving an error measure and the input pixel and responsive thereto for generating the corrected gray level.
Claim 17
Dependent Claim
54 words
The system for halftoning a digital image having a plurality of input pixels of claim 14 further comprising: an error distribution module coupled to the correction module for receiving an output gray level and a corrected gray level and responsive thereto for generating an error measure and distributing the error measure to future pixels.
Claim 18
Dependent Claim
69 words
The system for halftoning a digital image having a plurality of input pixels of claim 13 further comprising: an error determination module for receiving an output gray level and a corrected gray level and responsive thereto for generating an error measure; and an error distribution module coupled to the error determination module and the correction module for receiving the error measure and distributing the error measure to future pixels.
Claim 19
Independent Claim
106 words
A method for halftoning a digital image having a plurality of input pixels comprising: employing a look-up table to receive an input pixel and generate a reproducible gray level based on a gray level of at least one input pixel; receiving a corrected gray level and the reproducible gray level and determining whether the corrected gray level is in a predetermined relationship with a threshold; providing the reproducible gray level as output when the corrected gray level is in a predetermined relationship with the threshold; and providing a zero value as output when the corrected gray level is not in a predetermined relationship with the threshold.
Claim 20
Independent Claim
106 words
A method for halftoning a digital image having a plurality of input pixels comprising: employing a look-up table to receive an input pixel and generate a reproducible gray level based on a gray level of at least one input pixel; receiving a corrected gray level and the reproducible gray level and determining whether the corrected gray level is in a predetermined relationship with a threshold; providing the reproducible gray level as output when the corrected gray level is in a predetermined relationship with the threshold; and providing a zero value as output when the corrected gray level is not in a predetermined relationship with the threshold.
Claim 21
Dependent Claim
32 words
The method for halftoning a digital image having a plurality of input pixels of claim 17 further comprising: receiving an error measure and the input pixel and generating the corrected gray level.
Claim 22
Dependent Claim
41 words
The method for halftoning a digital image having a plurality of input pixels of claim 18 further comprising: receiving an output gray level and a corrected gray level and generating an error measure and distributing the error measure to future pixels.
Claim 23
Dependent Claim
46 words
The method for halftoning a digital image having a plurality of input pixels of claim 17 further comprising: receiving an output gray level and a corrected gray level and generating an error measure; and receiving the error measure and distributing the error measure to future pixels.
References Cited (Backward Citations)
US4680645A
Cited
EP0398763A2
Cited
US5077615A
Cited
US5359433A
Cited
WO1993026116A2
Cited
US5615021A
Cited
EP0719033A2
Cited
US5748336A
Cited
US5812744A
Cited
US6108450A
Cited
US6602003B2
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2007-08-17 | 2008-02-16 | 2008-08-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2011-08-17 | 2012-02-16 | 2012-08-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2015-08-17 | 2016-02-16 | 2016-08-17 | $7700.00 | Window Closed / Lapsed |