US5970178A
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Adaptive halftoning based on image content
Assignee: Hewlett Packard Development Co LP
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Filing: 1997-06-30
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Granted: 1999-10-19
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Expires: 2017-06-30
Abstract
Abstract A process and apparatus is described to improve halftone image quality by integrating different halftoning algorithms and managing their transitions based on image content. The method works by applying different halftoning methods to different regions of a continuous-tone image. Regions of the continuous-tone image are evaluated to determine suitability for halftoning by at least two different halftoning methods. The most suitable halftoning method is then used to halftone a particular region. An activity index is used to evaluate each region. A halftoning method such as error diffusion is deemed most suitable for application to detailed continuous-tone image areas. A halftoning method such as smooth dither is deemed most suitable for application to flat continuous-tone image areas . Also, hysteresis can be introduced to compensate for sharp transitions in the image and thereby eliminate ghosting.
Inventors
- 👤 Qian Lin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 20:00
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/405; H04N1/4051; H04N1/4052; H04N1/4053
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
71 words
A process for halftoning a continuous-tone image to form a halftone image, the process comprising the steps of: evaluating a region of the continuous-tone image to determine suitability for halftoning by at least two different halftoning methods; and halftoning the region using the most suitable halftoning method such that different halftoning methods are applied to different regions of the continuous-tone image, wherein an activity index is used to evaluate the region.
Claim 2
Dependent Claim
71 words
A process for halftoning a continuous-tone image to form a halftone image, the process comprising the steps of: evaluating a region of the continuous-tone image to determine suitability for halftoning by at least two different halftoning methods; and halftoning the region using the most suitable halftoning method such that different halftoning methods are applied to different regions of the continuous-tone image, wherein an activity index is used to evaluate the region.
Claim 3
Dependent Claim
37 words
The process as set forth in 1, wherein a first halftoning method is most suitable for application to detailed continuous-tone image areas and a second halftoning method is most suitable for application to flat continuous-tone image areas.
Claim 4
Dependent Claim
37 words
The process as set forth in 1, wherein a first halftoning method is most suitable for application to detailed continuous-tone image areas and a second halftoning method is most suitable for application to flat continuous-tone image areas.
Claim 5
Dependent Claim
17 words
The process as set forth in 2, wherein the first halftoning method is an error diffusion method.
Claim 6
Dependent Claim
17 words
The process as set forth in 2, wherein the first halftoning method is an error diffusion method.
Claim 7
Dependent Claim
15 words
The process as set forth in 2, wherein the second method is a dither method.
Claim 8
Dependent Claim
15 words
The process as set forth in 2, wherein the second method is a dither method.
Claim 9
Dependent Claim
71 words
A process for halftoning a continuous-tone image to form a halftone image, the process comprising the steps of: evaluating a region of the continuous-tone image to determine suitability for halftoning by at least two different halftoning methods; halftoning the region using the most suitable halftoning method such that different halftoning methods are applied to different regions of the continuous-tone image; and introducing hysteresis to compensate for sharp transitions in the image.
Claim 10
Dependent Claim
71 words
A process for halftoning a continuous-tone image to form a halftone image, the process comprising the steps of: evaluating a region of the continuous-tone image to determine suitability for halftoning by at least two different halftoning methods; halftoning the region using the most suitable halftoning method such that different halftoning methods are applied to different regions of the continuous-tone image; and introducing hysteresis to compensate for sharp transitions in the image.
Claim 11
Dependent Claim
37 words
The process as set forth in 5, wherein a first halftoning method is most suitable for application to detailed continuous-tone image areas and a second halftoning method is most suitable for application to flat continuous-tone image areas.
Claim 12
Dependent Claim
37 words
The process as set forth in 5, wherein a first halftoning method is most suitable for application to detailed continuous-tone image areas and a second halftoning method is most suitable for application to flat continuous-tone image areas.
Claim 13
Dependent Claim
17 words
The process as set forth in 6, wherein the first halftoning method is an error diffusion method.
Claim 14
Dependent Claim
17 words
The process as set forth in 6, wherein the first halftoning method is an error diffusion method.
Claim 15
Dependent Claim
15 words
The process as set forth in 6, wherein the second method is a dither method.
Claim 16
Dependent Claim
15 words
The process as set forth in 6, wherein the second method is a dither method.
Claim 17
Dependent Claim
72 words
A processor for halftoning a continuous-tone image to form a halftone image, the processor comprising: means for evaluating a region of the continuous-tone image to determine suitability for halftoning by at least two different halftoning methods; and means for halftoning the region using the most suitable halftoning method such that different halftoning methods are applied to different regions of the continuous-tone image, wherein an activity index is used to evaluate the region.
Claim 18
Dependent Claim
72 words
A processor for halftoning a continuous-tone image to form a halftone image, the processor comprising: means for evaluating a region of the continuous-tone image to determine suitability for halftoning by at least two different halftoning methods; and means for halftoning the region using the most suitable halftoning method such that different halftoning methods are applied to different regions of the continuous-tone image, wherein an activity index is used to evaluate the region.
Claim 19
Dependent Claim
37 words
The processor as set forth in 9, wherein a first halftoning method is most suitable for application to detailed continuous-tone image areas and a second halftoning method is most suitable for application to flat continuous-tone image areas.
Claim 20
Dependent Claim
37 words
The processor as set forth in 9, wherein a first halftoning method is most suitable for application to detailed continuous-tone image areas and a second halftoning method is most suitable for application to flat continuous-tone image areas.
Claim 21
Dependent Claim
17 words
The processor as set forth in 10, wherein the first halftoning method is an error diffusion method.
Claim 22
Dependent Claim
17 words
The processor as set forth in 10, wherein the first halftoning method is an error diffusion method.
Claim 23
Dependent Claim
15 words
The processor as set forth in 10, wherein the second method is a dither method.
Claim 24
Dependent Claim
15 words
The processor as set forth in 10, wherein the second method is a dither method.
Claim 25
Dependent Claim
74 words
A processor for halftoning a continuous-tone image to form a halftone image, the processor comprising: means for evaluating a region of the continuous-tone image to determine suitability for halftoning by at least two different halftoning methods; means for halftoning the region using the most suitable halftoning method such that different halftoning methods are applied to different regions of the continuous-tone image; and means for introducing hysteresis to compensate for sharp transitions in the image.
Claim 26
Dependent Claim
74 words
A processor for halftoning a continuous-tone image to form a halftone image, the processor comprising: means for evaluating a region of the continuous-tone image to determine suitability for halftoning by at least two different halftoning methods; means for halftoning the region using the most suitable halftoning method such that different halftoning methods are applied to different regions of the continuous-tone image; and means for introducing hysteresis to compensate for sharp transitions in the image.
Claim 27
Dependent Claim
37 words
The processor as set forth in 13, wherein a first halftoning method is most suitable for application to detailed continuous-tone image areas and a second halftoning method is most suitable for application to flat continuous-tone image areas.
Claim 28
Dependent Claim
37 words
The processor as set forth in 13, wherein a first halftoning method is most suitable for application to detailed continuous-tone image areas and a second halftoning method is most suitable for application to flat continuous-tone image areas.
Claim 29
Dependent Claim
17 words
The processor as set forth in 14, wherein the first halftoning method is an error diffusion method.
Claim 30
Dependent Claim
17 words
The processor as set forth in 14, wherein the first halftoning method is an error diffusion method.
Claim 31
Dependent Claim
15 words
The processor as set forth in 14, wherein the second method is a dither method.
Claim 32
Dependent Claim
15 words
The processor as set forth in 14, wherein the second method is a dither method.
References Cited (Backward Citations)
US4974097A
Cited
US5701366A
Cited
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