reliable dual-band based contour detection a double dynamic programming approach mohammad dawood,...

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.