Patent US5845007A successfully refreshed from Google Patents.
US5845007A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Machine vision method and apparatus for edge-based image histogram analysis
Assignee: Cognex Corp
•
Filing: 1996-01-02
•
Granted: 1998-12-01
•
Expires: 2016-01-02
Abstract
Abstract A system for edge-based image histogram analysis permits identification of predominant characteristics of edges in an image. The system includes an edge detector that generates an edge magnitude image having a plurality of edge magnitude values based on pixels in the input image. The edge detector can be a Sobel operator that generates the magnitude values by taking the derivative of the input image values, i.e., the rate of change of intensity over a plurality of image pixels. A mask generator creates a mask based upon the values output by the edge detector. The mask can be used for masking input image values that are not in a region for which there is a sufficiently high edge magnitude. A mask applicator applies the pixel mask array to a selected image, e.g., the input image or an image generated therefrom (such as an edge direction image of the type resulting from application of a Sobel operator to the input image). A histogram generator generates a histogram of the pixel values in the masked image, i.e., a count of the number of image pixels that pass through the mask. A peak detector identifies the intensity value in the histogram that represents the predominant image intensity value (image segmentation threshold) or predominant edge direction values associated with the edge detected by the edge detector.
Inventors
- 👤 Yoshikazu Ohashi
- 👤 Russ Weinzimmer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 09:36
CPC Classifications
G; G06; G06T; G06T7/00; G06T7/10; G06T7/12
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
192 words
An apparatus for determining a characteristic of an edge represented in an input image that includes a plurality of input image pixels, the apparatus comprising: edge magnitude detection means for generating an edge magnitude image including a plurality of edge magnitude pixels, each having a value that is indicative of a rate of change of a plurality of values of respective input image pixels; mask generating means, coupled with the edge magnitude detection means, for generating an array of pixel masks, each having a value that is masking or non-masking and that is dependent on a value of one or more respective edge magnitude pixels; mask applying means, coupled to the mask generating means, for generating a masked image including only those pixels from a selected image that correspond to non-masking values in the array; histogram means, coupled to the mask applying means, for generating a histogram of pixels in the masked image; and peak detection means, coupled with the histogram means, for identifying in the histogram at least one value indicative of a predominant characteristic of an edge represented in the input image and for outputting a signal representing that value.
Claim 2
Independent Claim
192 words
An apparatus for determining a characteristic of an edge represented in an input image that includes a plurality of input image pixels, the apparatus comprising: edge magnitude detection means for generating an edge magnitude image including a plurality of edge magnitude pixels, each having a value that is indicative of a rate of change of a plurality of values of respective input image pixels; mask generating means, coupled with the edge magnitude detection means, for generating an array of pixel masks, each having a value that is masking or non-masking and that is dependent on a value of one or more respective edge magnitude pixels; mask applying means, coupled to the mask generating means, for generating a masked image including only those pixels from a selected image that correspond to non-masking values in the array; histogram means, coupled to the mask applying means, for generating a histogram of pixels in the masked image; and peak detection means, coupled with the histogram means, for identifying in the histogram at least one value indicative of a predominant characteristic of an edge represented in the input image and for outputting a signal representing that value.
Claim 3
Dependent Claim
84 words
An apparatus according to claim 1, wherein the input image pixels have values indicative of image intensity, the improvement wherein the mask applying means generates the masked image to include only those pixels of the input image that correspond to non-masking values in the array; and the peak detection means identifies in the histogram a peak value indicative of a predominant image intensity value of an edge represented in the input image and for outputting a signal indicative of that predominant image intensity value.
Claim 4
Dependent Claim
28 words
An apparatus according to claim 2, wherein the edge magnitude detection means applies a Sobel operator to the input image in order to generate the edge magnitude image.
Claim 5
Dependent Claim
116 words
An apparatus according to claim 1, further comprising: edge direction detection means for generating an edge direction image including a plurality of edge direction pixels, each having a value that is indicative of an direction of rate of change of a plurality of values of respective input image pixels; mask applying means includes means for generating the masked image as including only those pixels of the edge direction image that correspond to non-masking values in the array; and the peak detection means identifies in the histogram a peak value indicative of a predominant edge direction value of an edge represented in the input image and for outputting a signal indicative of that predominant edge direction value.
Claim 6
Dependent Claim
28 words
An apparatus according to claim 4, wherein the edge direction detection means applies a Sobel operator to the input image in order to generate the edge direction image.
Claim 7
Independent Claim
56 words
An apparatus according to any of claims 2 and 4, wherein the mask generating means sharpens peaks in the edge magnitude image and generates a sharpened edge magnitude image representative thereof and having a plurality of sharpened edge magnitude pixels; and generates the array of pixel masks to be dependent on the sharpened edge magnitude pixels.
Claim 8
Dependent Claim
50 words
An apparatus according to claim 6, wherein the mask generating generates each pixel mask to have a masking value for edge magnitude values that are in a first numerical range and for generating a pixel mask to have a non-masking for magnitude values that are in a second numerical range.
Claim 9
Dependent Claim
48 words
An apparatus according to claim 7, wherein mask generating means generates each pixel mask to have a masking value for edge magnitude values that are below a threshold value and for generating a pixel mask to have a non-masking for magnitude values that are above a threshold value.
Claim 10
Independent Claim
171 words
A method for determining a characteristic of an edge represented in an input image that includes a plurality of input image pixels, the method comprising: an edge magnitude detection step for generating an edge magnitude image including a plurality of edge magnitude pixels, each having a value that is indicative of a rate of change of one or more values of respective input image pixels; a mask generating step for generating an array of pixel masks, each having a value that is masking or non-masking and that is dependent on a value of one or more respective edge magnitude pixels; a mask applying step for generating a masked image including only those pixels from a selected image that correspond to non-masking values in the array; a histogram step for generating a histogram of pixels in the masked image; and a peak detection step for identifying in the histogram a value indicative of a predominant characteristic of an edge represented in the input image and for outputting a signal representing that value.
Claim 11
Independent Claim
171 words
A method for determining a characteristic of an edge represented in an input image that includes a plurality of input image pixels, the method comprising: an edge magnitude detection step for generating an edge magnitude image including a plurality of edge magnitude pixels, each having a value that is indicative of a rate of change of one or more values of respective input image pixels; a mask generating step for generating an array of pixel masks, each having a value that is masking or non-masking and that is dependent on a value of one or more respective edge magnitude pixels; a mask applying step for generating a masked image including only those pixels from a selected image that correspond to non-masking values in the array; a histogram step for generating a histogram of pixels in the masked image; and a peak detection step for identifying in the histogram a value indicative of a predominant characteristic of an edge represented in the input image and for outputting a signal representing that value.
Claim 12
Dependent Claim
92 words
A method according to claim 9, wherein the input image pixels have values indicative of image intensity, the improvement wherein the mask applying step includes the step of generating the masked image to include only those pixels of the input image that correspond to non-masking values in the array; and the peak detection step includes a step for identifying in the histogram a peak value indicative of a predominant image intensity value of an edge represented in the input image and for outputting a signal indicative of that predominant image intensity value.
Claim 13
Dependent Claim
32 words
A method according to claim 10, wherein the edge magnitude detection step includes a step for applying a Sobel operator to the input image in order to generate the edge magnitude image.
Claim 14
Dependent Claim
122 words
A method according to claim 9, comprising an edge direction detection step for generating an edge direction image including a plurality of edge direction pixels, each having a value that is indicative of an direction of rate of change of one or more values of respective input image pixels; the mask applying step includes the step of generating the masked image as including only those pixels of the edge direction image that correspond to non-masking values in the array; and the peak detection step includes a step for identifying in the histogram a peak value indicative of a predominant edge direction value of an edge represented in the input image and for outputting a signal indicative of that predominant edge direction value.
Claim 15
Dependent Claim
32 words
A method according to claim 12, wherein the edge direction detection step includes a step for applying a Sobel operator to the input image in order to generate the edge direction image.
Claim 16
Independent Claim
64 words
A method according to any of claims 10 and 12, wherein the mask generating step includes a step for sharpening peaks in the edge magnitude image and for generating a sharpened edge magnitude image representative thereof and having a plurality of sharpened edge magnitude pixels; and a step for generating the array of pixel masks to be dependent on the sharpened edge magnitude pixels.
Claim 17
Dependent Claim
56 words
A method according to claim 14, wherein the mask generating step includes a binarization step for generating each pixel mask to have a masking value for edge magnitude values that are in a first numerical range and for generating a pixel mask to have a non-masking for magnitude values that are in a second numerical range.
Claim 18
Dependent Claim
52 words
A method according to claim 15, wherein the binarization step includes the step of generating each pixel mask to have a masking value for edge magnitude values that are below a threshold value and for generating a pixel mask to have a non-masking for magnitude values that are above a threshold value.
Claim 19
Dependent Claim
185 words
An article of manufacture comprising a computer usable medium embodying program code for causing a digital data processor to carry out a method for determining a characteristic of an edge represented in an input image that includes a plurality of input image pixels, the method comprising an edge magnitude detection step for generating an edge magnitude image including a plurality of edge magnitude pixels, each having a value that is indicative of a rate of change of one or more values of respective input image pixels; a mask generating step for generating an array of pixel masks, each having a value that is masking or non-masking and that is dependent on a value of one or more respective edge magnitude pixels; a histogram-generating step for applying the array of pixel masks to a selected image for generating a histogram of values of pixels therein that correspond to non-masking values in the array; and a peak detection step for identifying in the histogram a value indicative of a predominant characteristic of an edge represented in the input image and for outputting a signal representing that value.
Claim 20
Dependent Claim
185 words
An article of manufacture comprising a computer usable medium embodying program code for causing a digital data processor to carry out a method for determining a characteristic of an edge represented in an input image that includes a plurality of input image pixels, the method comprising an edge magnitude detection step for generating an edge magnitude image including a plurality of edge magnitude pixels, each having a value that is indicative of a rate of change of one or more values of respective input image pixels; a mask generating step for generating an array of pixel masks, each having a value that is masking or non-masking and that is dependent on a value of one or more respective edge magnitude pixels; a histogram-generating step for applying the array of pixel masks to a selected image for generating a histogram of values of pixels therein that correspond to non-masking values in the array; and a peak detection step for identifying in the histogram a value indicative of a predominant characteristic of an edge represented in the input image and for outputting a signal representing that value.
References Cited (Backward Citations)
US3936800A
Cited
US4115702A
Cited
US4183013A
Cited
US4115762A
Cited
US4200861A
Cited
US4441206A
Cited
US4570180A
Cited
US4736437A
Cited
US4860374A
Cited
US4688088A
Cited
US4922543A
Cited
US4685143A
Cited
US4876728A
Cited
US4783826A
Cited
US4955062A
Cited
US5081656A
Cited
US4962243A
Cited
US4876457A
Cited
US5081689A
Cited
US5153925A
Cited
US5073958A
Cited
US5134575A
Cited
US4959898A
Cited
US5113565A
Cited
US5206820A
Cited
US5086478A
Cited
US5133022A
Cited
US5225940A
Cited
US5265173A
Cited
US5273040A
Cited
US5371690A
Cited
US5398292A
Cited
US5525883A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-11-30 | 2002-06-01 | 2002-12-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-11-30 | 2006-06-01 | 2006-12-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-11-30 | 2010-06-01 | 2010-12-01 | $7700.00 | Window Closed / Lapsed |