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US6072907A
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Method and apparatus for enhancing and thresholding images
Assignee: Xerox Corp
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Filing: 1998-05-19
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Granted: 2000-06-06
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Expires: 2018-05-19
Abstract
Abstract An image processing method and system for generating enhanced binary image data from greyscale input image data. The method includes the steps of (a) receiving first image data, the first image data being greyscale image data defining an input image, (b) performing a high frequency boost operation on the first image data to produce second image data, (c) performing a linear interpolation operation on the second image data to produce third image data, the third image data having a resolution higher than the resolution of the second image data, (d) performing a contrast enhancement operation on the third image data to produce fourth image data, and (e) thresholding the fourth image data to produce fifth image data, the fifth image data being binary image data defining an output image. The techniques find application, for example, in over-the-desk scanning of documents, and in video-conferencing.
Inventors
- 👤 Michael J. Taylor
- 👤 Anthony Zappala
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 19:46
CPC Classifications
G; G06; G06T; G06T5/00; G06T5/90; G06T5/92; G06T7/00; G06T7/10; G06T7/11; G06T7/136; G06V; G06V30/00; G06V30/10; G06V30/16; G06V30/162; G06T2207/00; G06T2207/10; G06T2207/10004; G06T2207/10008; G06T2207/10016; G06T2207/20; G06T2207/20004; G06T2207/20012; G06T2207/30; G06T2207/30176
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
130 words
A method for converting a low resolution greyscale image to a high resolution binary image with an image processing system, comprising the steps of: (a) receiving first image data; the first image data being greyscale image data defining an input image; (b) performing a high frequency boost operation on the first image data to produce second image data; (c) performing a linear interpolation operation on the second image data to produce third image data; the third image data having a resolution higher than the resolution of the second image data; (d) performing a contrast enhancement operation on the third image data to produce fourth image data; and (e) thresholding the fourth image data to produce fifth image data; the fifth image data being binary image data defining an output image.
Claim 2
Independent Claim
130 words
A method for converting a low resolution greyscale image to a high resolution binary image with an image processing system, comprising the steps of: (a) receiving first image data; the first image data being greyscale image data defining an input image; (b) performing a high frequency boost operation on the first image data to produce second image data; (c) performing a linear interpolation operation on the second image data to produce third image data; the third image data having a resolution higher than the resolution of the second image data; (d) performing a contrast enhancement operation on the third image data to produce fourth image data; and (e) thresholding the fourth image data to produce fifth image data; the fifth image data being binary image data defining an output image.
Claim 3
Dependent Claim
28 words
The method according to claim 1, wherein said step (d) further comprises the steps of: (d1) computing high gradient image data (g(x,y)) using the third image data (f(x,y)).
Claim 4
Dependent Claim
29 words
The method according to claim 2, wherein said step (d1) comprises applying a Sobel operator to the third image data (f(x,y)) to produce the high gradient image data (g(x,y)).
Claim 5
Dependent Claim
31 words
The method according to claim 2, wherein said step (d) further comprises the step of: (d2) computing sum image data (s(x,y)) from partial sums of the high gradient image data (g(x,y)).
Claim 6
Dependent Claim
21 words
The method according to claim 4, wherein said step (d2) computes the sum image data (s(x,y)) with the following equation: ##EQU2##
Claim 7
Dependent Claim
52 words
The method according to claim 4, wherein said step (d) further comprises performing for each pixel datum of the third image data (f(x,y)) the step of: (d3) applying a contrast enhancement function (e(m)) to the third image data; the contrast enhancement function being dependent on a local average (m(x,y)) of pixel data.
Claim 8
Dependent Claim
48 words
The method according to claim 6, wherein step (d3) further comprises the steps of: (d3i) computing a local average (m(x,y)) of pixel data; (d3ii) forming the contrast enhancing function (e(m)) based on the local average; and (d3iii) applying the contrast enhancement function (e(m)) to the third image data.
Claim 9
Dependent Claim
68 words
The method according to claim 7, wherein said step (d3i) computes the local average m i for a pixel f i using the following equation: m.sub.i =S.sub.i /N.sub.i, where S i is the sum of high-gradient image data in an N by N neighbourhood about f i , and N i is the number of high gradient pixels in the N by N neighbourhood about f i .
Claim 10
Dependent Claim
48 words
The method according to claim 8, wherein said step (d3i) computes the sum of high gradient pixels S i in an N by N neighbourhood about f i using the following equation: S.sub.i =S(c,d)-S(a,d)-S(c,b)+S(a,b), where, S(c,d), S(a,d), S(c,b), and S(a,b) are elements of the sum image data s(x,y).
Claim 11
Dependent Claim
163 words
An image processing system for converting a low resolution greyscale image to a high resolution binary image, comprising: a memory for storing the low resolution greyscale image, the high resolution binary image, and image processing instructions; and a processor coupled to the memory for executing the image processing instructions; the processor in executing the image processing instructions: (a) receiving first image data; the first image data being greyscale image data defining an input image; (b) performing a high frequency boost operation on the first image data to produce second image data; (c) performing a linear interpolation operation on the second image data to produce third image data; the third image data having a resolution higher than the resolution of the second image data; (d) performing a contrast enhancement operation on the third image data to produce fourth image data; and (e) thresholding the fourth image data to produce fifth image data, the fifth image data being binary image data defining an output image.
Claim 12
Dependent Claim
163 words
An image processing system for converting a low resolution greyscale image to a high resolution binary image, comprising: a memory for storing the low resolution greyscale image, the high resolution binary image, and image processing instructions; and a processor coupled to the memory for executing the image processing instructions; the processor in executing the image processing instructions: (a) receiving first image data; the first image data being greyscale image data defining an input image; (b) performing a high frequency boost operation on the first image data to produce second image data; (c) performing a linear interpolation operation on the second image data to produce third image data; the third image data having a resolution higher than the resolution of the second image data; (d) performing a contrast enhancement operation on the third image data to produce fourth image data; and (e) thresholding the fourth image data to produce fifth image data, the fifth image data being binary image data defining an output image.
Claim 13
Dependent Claim
69 words
The image processing system according to claim 10, further comprising an interactive desktop system including: a work surface; a display device for displaying images in a display area; and an image capture device for capturing images present on the work surface; wherein said processor is coupled to said display device and said image capture device for displaying the output image in at least a portion of said display area.
Claim 14
Dependent Claim
23 words
The image processing system according to claim 10, further comprising a communications link for transmitting the fifth image data to a second processor.
Claim 15
Dependent Claim
70 words
The image processing system according to claim 10, further comprising image processing instructions for (d1) computing high gradient image data (g(x,y)) using the third image data (f(x,y)); (d2) computing sum image data (s(x,y)) from partial sums of the high gradient image data (g(x,y)); and (d3) applying a contrast enhancement function (e(m)) to the third image data; the contrast enhancement function being dependent on a local average (m(x,y)) of pixel data.
Claim 16
Dependent Claim
35 words
The image processing system according to claim 13, wherein said instruction (d1) further comprises an instruction for applying a Sobel operator to the third image data (f(x,y)) to produce the high gradient image data (g(x,y)).
Claim 17
Dependent Claim
28 words
The image processing system according to claim 13, wherein said instruction (d2) further comprises an instruction for computing the sum image data (s(x,y)) with the following equation: ##EQU3##
Claim 18
Dependent Claim
50 words
The image processing system according to claim 13, wherein said instruction (d) further comprises instructions for: (d3i) computing a local average (m(x,y)) of pixel data; (d3ii) forming the contrast enhancing function (e(m)) based on the local average; and (d3iii) applying the contrast enhancement function (e(m)) to the third image data.
Claim 19
Dependent Claim
70 words
The image processing system according to claim 16, wherein said instruction (d3i) computes the local average m i for a pixel f i using the following equation: m.sub.i =S.sub.i /N.sub.i, where S i is the sum of high-gradient image data in an N by N neighbourhood about f i , and N i is the number of high gradient pixels in the N by N neighbourhood about f i .
Claim 20
Dependent Claim
50 words
The image processing system according to claim 17, wherein said instruction (d3i) computes the sum of high gradient pixels S i in an N by N neighbourhood about f i using the following equation: S.sub.i =S(c,d)-S(a,d)-S(c,b)+S(a,b), where, S(c,d), S(a,d), S(c,b), and S(a,b) are elements of the sum image data s(x,y).
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| 3.5 Years (Year 4) | 2003-06-06 | 2003-12-06 | 2004-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-06-06 | 2007-12-06 | 2008-06-06 | $3760.00 | Window Closed / Lapsed |
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