US4794531A
Expired / Lapsed
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Unsharp masking for image enhancement
Assignee: Hitachi Healthcare Manufacturing Ltd
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Filing: 1987-04-22
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Granted: 1988-12-27
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Expires: 2007-04-22
Abstract
Abstract In an unsharp masking processing for sharpening images such as radiographic images, an emphasizing coefficient of an image and parameters for real-time change of picture quality are set interactively. The entire image is divided into a plurality of regional images and filtering optimized for each pixel image is effected using a standard deviation computed for each regional image and a density difference between pixel images.
Inventors
- 👤 Koichi Morishita
- 👤 Shimbu Yamagata
- 👤 Tetsuo Okabe
- 👤 Tetsuo Yokoyama
- 👤 Kazuhiko Hamatani
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 04:29
CPC Classifications
G; G06; G06T; G06T5/00; G06T5/73; G06T5/75; G06T5/20
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
122 words
A method of radiographic image enhancement for an unsharp masking processing, comprising the steps of dividing an image into a plurality of local images; obtaining an unsharp image by averaging neighboring pixel values at local regions of the original image; subtracting the unsharp image from the original image to produce a sharp image; and adding an original image at a desired ratio to the sharp image to create a processed image, wherein said averaging step comprises effecting a weighted mean arithmetic operation of the pixel values of the local regions based on a weight coefficient which is determined in accordance with a monotonically decreasing or increasing function with respect to a density difference between a central pixel value and neighboring pixel values.
Claim 2
Independent Claim
122 words
A method of radiographic image enhancement for an unsharp masking processing, comprising the steps of dividing an image into a plurality of local images; obtaining an unsharp image by averaging neighboring pixel values at local regions of the original image; subtracting the unsharp image from the original image to produce a sharp image; and adding an original image at a desired ratio to the sharp image to create a processed image, wherein said averaging step comprises effecting a weighted mean arithmetic operation of the pixel values of the local regions based on a weight coefficient which is determined in accordance with a monotonically decreasing or increasing function with respect to a density difference between a central pixel value and neighboring pixel values.
Claim 3
Dependent Claim
44 words
A method of radiographic image enhancement according to claim 1, wherein said ratio is determined in accordance with a standard deviation of density values of the local regions, and a composite value of the standard deviation and the density value of the original image.
Claim 4
Dependent Claim
18 words
A method of radiographic image enhancement according to claim 1 wherein said ratio is set at a constant.
Claim 5
Dependent Claim
52 words
A method of radiographic image enhancement according to claim 1, further comprising a step of changing an emphasizing coefficient of said sharp image in accordance with a standard deviation of density values of the local regions or a composite value of the standard deviation and the original image density, interactively and consecutively.
Claim 6
Dependent Claim
33 words
A method of radiographic image enhancement according to claim 4, wherein said changing step includes a step for interactively designating a size of a local region used for formation of the unsharp image.
Claim 7
Dependent Claim
28 words
A method of radiographic image enhancement according to claim 4, wherein said changing step includes a step for interactively designating a level of brightness of a processed image.
Claim 8
Dependent Claim
41 words
A method of radiographic image enhancement according to claim 4, wherein said changing step includes a step for storing values of said emphasizing coefficient, a size of a local region and a level of brightness inputted interactively as picture quality parameters.
Claim 9
Dependent Claim
35 words
A method of radiographic image enhancement according to claim 7, wherein said changing step includes a step of reading said stored picture quality parameter values and automatically setting the picture quality parameters for executing emphasizing.
References Cited (Backward Citations)
JPS60171573A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-12-27 | 1992-06-27 | 1992-12-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-12-27 | 1996-06-27 | 1996-12-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-12-27 | 2000-06-27 | 2000-12-27 | $7700.00 | Window Closed / Lapsed |