US5268967A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for automatic foreground and background detection in digital radiographic images
Assignee: Carestream Health Inc
•
Filing: 1992-06-29
•
Granted: 1993-12-07
•
Expires: 2012-06-29
Abstract
Abstract A digital image processing method automatically separates (segments) the desired regions in a digital radiographic image (i.e., the body part being imaged) from the undesired regions (background areas around the body part that have received unattenuated radiation or foreground areas that have received very little radiation due to the use of radiation limiting devices). The method includes the steps of edge detection, block generation, block classification, block refinement and bit map generation.
Inventors
- 👤 Ben K. Jang
- 👤 Ralph Schaetzing
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:48
CPC Classifications
G; G06; G06T; G06T7/00; G06T7/0002; G06T7/0012; G06T7/10; G06T7/11; G06T7/187; G06T7/194; G06T2207/00; G06T2207/10; G06T2207/10116; G06T2207/30; G06T2207/30004
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
129 words
A method for automatically segmenting desired regions in a digital radiographic image signal from undesired regions, comprising the steps of: providing a digital radiographic image signal including a foreground region, a background region, and an object region; detecting edges in the image signal based on a morphological edge detector; decomposing said image signal into a set of nonoverlapping, contiguous blocks of pixel signals; classifying a block of pixel signals to be homogeneous or nonhomogeneous as a function of its edge density and variance; applying a set of syntactic rules to detect the nonhomogeneous blocks of pixel signals in the foreground/background, as well as the homogeneous blocks of pixel signals in the object; refining the blocks consisting of a mixture of object and foreground/background; and producing a segmented image signal.
Claim 2
Independent Claim
129 words
A method for automatically segmenting desired regions in a digital radiographic image signal from undesired regions, comprising the steps of: providing a digital radiographic image signal including a foreground region, a background region, and an object region; detecting edges in the image signal based on a morphological edge detector; decomposing said image signal into a set of nonoverlapping, contiguous blocks of pixel signals; classifying a block of pixel signals to be homogeneous or nonhomogeneous as a function of its edge density and variance; applying a set of syntactic rules to detect the nonhomogeneous blocks of pixel signals in the foreground/background, as well as the homogeneous blocks of pixel signals in the object; refining the blocks consisting of a mixture of object and foreground/background; and producing a segmented image signal.
Claim 3
Dependent Claim
25 words
The method of claim 1 wherein the shape and size of a pixel block can be adjusted according to the size of said image signal.
Claim 4
Dependent Claim
27 words
The method of claim 1 wherein said refining step refines a pixel block consisting of a mixture of object and foreground/background pixels, based on its local statistics.
Claim 5
Dependent Claim
70 words
The method of claim 1 wherein said set of syntactic rules includes one or more of the following rules: (a) a rule or rules to detect the foreground/background regions which are nonhomogeneous; (b) a rule or rules to detect object regions which are nonhomogeneous; (c) a rule or rules to detect the object regions which are homogeneous; (d) a rule or rules to detect the foreground/background regions which are homogeneous.
Claim 6
Dependent Claim
56 words
The method of claim 1 wherein in said applying syntactic rules step a set of clinically and empirically determined decision rules is used to relate various structures of said image signal, and then to detect the nonhomogeneous blocks of pixel signals in the foreground/background, as well as the homogeneous blocks of pixel signals in the object.
Claim 7
Dependent Claim
34 words
The method of claim 1 wherein the pixel block classifying step is done by classifying each pixel block into one of ten possible states, depending on its degree of homogeneity and what it contains.
Claim 8
Dependent Claim
42 words
The method of claim 6 wherein said ten possible classification states are: (a) homogeneous background; (b) homogeneous foreground; (c) homogeneous object; (d) nonhomogeneous background; (e) nonhomogeneous foreground; (f) nonhomogeneous object; (g) mixed: background+foreground; (h) mixed: background+object; (i) mixed: foreground+object; (j) mixed: background+foreground+object.
Claim 9
Dependent Claim
20 words
The method of claim 1, including the step of smoothing said digital radiographic image signal before said edge detecting step.
Claim 10
Dependent Claim
16 words
The method of claim 8 wherein said smoothing step is effected by a spatial filtering operation.
Claim 11
Dependent Claim
25 words
The method of claim 9 wherein said spatial filtering operation includes averaging each pixel of said digital image with the eight nearest neighboring pixels thereof.
Claim 12
Dependent Claim
54 words
The method of claim 1 wherein said morphological edge detector produces an edge strength signal, g(x,y), having the following formula: g(x,y)=min[ƒB-ƒθB,ƒ⊕B-ƒ.multidot.B](x,y) where ƒ is the smoothed said image signal and B is used to interact with said image signal and is a structuring element which is similar to a kernal in a convolution operation.
Claim 13
Dependent Claim
29 words
The method of claim 11 wherein said structuring element of the morphological edge detector can be decomposed into a number of smaller pixel subsets to improve the implementation efficiency.
Claim 14
Dependent Claim
26 words
The method of claim 11 wherein said edge strength signal has high-amplitude in areas of strong edges and low-amplitude in areas of weak or no edges.
Claim 15
Dependent Claim
28 words
The method of claim 1 wherein said detecting edges step identifies edges as those pixels where said edge strength signal has amplitudes exceeding an edge strength threshold value.
Claim 16
Dependent Claim
31 words
The method of claim 14 wherein said edge strength threshold value is automatically determined by maximizing the product of said edge strength threshold and the number of pixels at that threshold.
References Cited (Backward Citations)
US4851678A
Cited
US4804842A
Cited
US4731863A
Cited
US4859850A
Cited
US5028782A
Cited
US4967079A
Cited
US4829181A
Cited
EP0288042A2
Cited
US4952805A
Cited
US5040225A
Cited
US4962539A
Cited
US5101280A
Cited
US5150433A
Cited
US5050222A
Cited
US5093869A
Cited
US5164993A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-12-06 | 1997-06-07 | 1997-12-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-12-06 | 2001-06-07 | 2001-12-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-12-06 | 2005-06-07 | 2005-12-07 | $7700.00 | Window Closed / Lapsed |