reliable dual-band based contour detection a double dynamic programming approach mohammad dawood,...
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Reliable Dual-Band Based Contour DetectionA Double Dynamic Programming Approach
Mohammad Dawood, Xiaoyi Jiang, Klaus P Schäfers
Motivation
Contour detection in a restricted search space is:
• More reliable
• Fast
Institute for Computer Science, University of MünsterDepartment of Nuclear Medicine, University Hospital Münster
Computer Tomograph image Positron Emission Tomograph image
Reliable Dual-Band Based Contour DetectionA Double Dynamic Programming Approach
Mohammad Dawood, Xiaoyi Jiang, Klaus P Schäfers
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Restricting the Search Space
• Bounding box
Reliable Dual-Band Based Contour DetectionA Double Dynamic Programming Approach
Mohammad Dawood, Xiaoyi Jiang, Klaus P Schäfers
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Restricting the Search Space
• Bounding box
• Dual snakes
Reliable Dual-Band Based Contour DetectionA Double Dynamic Programming Approach
Mohammad Dawood, Xiaoyi Jiang, Klaus P Schäfers
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Restricting the Search Space
• Bounding box
• Dual snakes
• Surface normals
Our approach: Dual band
Reliable Dual-Band Based Contour DetectionA Double Dynamic Programming Approach
Mohammad Dawood, Xiaoyi Jiang, Klaus P Schäfers
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The procedure
• Step 1: Form the dual band from the initial contour
• Step 2: Interlink the dual band boundaries
• Step 3: Find the target contour within the dual band
Reliable Dual-Band Based Contour DetectionA Double Dynamic Programming Approach
Mohammad Dawood, Xiaoyi Jiang, Klaus P Schäfers
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Dynamic Programming
Optimal solutions of sub-problems add up to global optimum, provided the sub-problems depend upon the steps before them only and there is sequence of sub-problems.
• Global optimum
• Fast
• Non-iterative
Reliable Dual-Band Based Contour DetectionA Double Dynamic Programming Approach
Mohammad Dawood, Xiaoyi Jiang, Klaus P Schäfers
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Step 1: Defining the Dual-Band
• Our Approach: Morphological dilation and erosion
Reliable Dual-Band Based Contour DetectionA Double Dynamic Programming Approach
Mohammad Dawood, Xiaoyi Jiang, Klaus P Schäfers
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Step 1: Defining the Dual-Band
• Our Approach: Morphological dilation and erosion
Reliable Dual-Band Based Contour DetectionA Double Dynamic Programming Approach
Mohammad Dawood, Xiaoyi Jiang, Klaus P Schäfers
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Step 2: Defining the links
• Use dynamic programming to find the best match between points on the dual contour
• Use the sum of lengths of the connecting lines as cost function
Reliable Dual-Band Based Contour DetectionA Double Dynamic Programming Approach
Mohammad Dawood, Xiaoyi Jiang, Klaus P Schäfers
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Step 2: Defining the links
• Use dynamic programming to find the best match between points on the dual contour
• Use the sum of lengths of the connecting lines as cost functionInner Contour
Out
er C
onto
ur
Reliable Dual-Band Based Contour DetectionA Double Dynamic Programming Approach
Mohammad Dawood, Xiaoyi Jiang, Klaus P Schäfers
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Step 3: Finding the Contour in the Dual-Band
• Use the connecting lines as rows of the image matrix
• Define a cost function to find the best contour
9 9 0 6
9 6 6 4
1 7 5 4
… … … …
Image Image Matrix
3 0 9 6
5 3 0 2
3 6 2 1
… … … …
Cost Matrix
Reliable Dual-Band Based Contour DetectionA Double Dynamic Programming Approach
Mohammad Dawood, Xiaoyi Jiang, Klaus P Schäfers
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Experimental ResultsTracking
Reliable Dual-Band Based Contour DetectionA Double Dynamic Programming Approach
Mohammad Dawood, Xiaoyi Jiang, Klaus P Schäfers
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Experimental ResultsSegmenting lungs on PET images
Reliable Dual-Band Based Contour DetectionA Double Dynamic Programming Approach
Mohammad Dawood, Xiaoyi Jiang, Klaus P Schäfers
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Conclusion and Future Work
We have developed a:
• fast • non-iterative• robust procedure
for contour detection in restricted search space
• Work on 3D extension is already underway.