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A Fast and Efficient VOP Extraction Method Based on Watershed Segmentation Alireza Tavakkoli Dr....
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Transcript of A Fast and Efficient VOP Extraction Method Based on Watershed Segmentation Alireza Tavakkoli Dr....
A Fast and Efficient VOP Extraction Method Based on Watershed Segmentation
Alireza TavakkoliDr. Shohreh Kasaei
Gholamreza AmayehSharif University of Technology
2
Outline
Problem Definition. Literature Review. Proposed Method. Performance Analysis. Conclusions.
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Content-Based Functionalities in Video
User Interaction. Very Low Bit-rate Video
Compression. Video Indexing.
Object-Based Video Coding Systems: MPEG 4. H.263.
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Video Object Plane (VOP). A Video Scene is decomposed into VOPs. Multiple VOPs shape Video Object Layers. Proposing an Automatic VOP Extractor is a very difficult task.
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VOP Extraction
Spatio-Temporal Segmentation: Spatial Segmentation:
Watershed Segmentation. Temporal Information:
Motion Detection. Change Detection Masks.
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Watershed Segmentation Rain Fall Simulation:
Immersion Simulation: Vincent & Soille
(1991).
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Drawbacks of Watershed Segmentation
Results in over segmentation. Very time consuming. Solutions:
Region Merging Techniques. Predictive Watershed.
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Over Segmentation
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Region Merging Using Modified Gradient
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Preparing Image for Watershed Segmentation
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Resulting Watershed Segmentation
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Predictive Watershed Some Definitions:
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Prediction of Watershed
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Why CDM? Distance Learning Application:
Video is supposed to have stationary Background.
Real time video compression system. Stationary Background:
No Global Motion. No Camera Motion. No Illumination Changes.
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CDM and Noise Difference Noise:
Gaussian Noise: Due to intensity
changes. Can be reduced by
a Hypothesis test. Hypothesis test:
Noise if H0 True. Object if H1 True.
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Region Labeling Method Hypothesis Test
objx
objx
w dif
i
dif
i
dif
cameradif
thDPH
thDPH
yxObjD
dDif
1
0
2
2
2
2
2
22
,
2exp
2
1
2
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Watershed Update
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VOP Extraction Algorithm
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Experimental Results
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Experimental Results (Contd.)
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Experimental Results (Contd.)
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Experimental Results (Contd.)
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Experimental Results (Contd.)
Seq. Name
Frame Watershed
Method
Number of
Pixels
Number of
Regions
Time (msc.)
≈
Hall& Monitor
F-Frame Soile 84480 5961 10
Proposed
84480 396 20
P-Frame Proposed
1346 29 2
Walking Daniel
F-Frame Soile 110592 3749 10
Proposed
110592 352 20
P-Frame Proposed
2565 21 2
Matlab 6.2 Software, Pentium 4, 2.0GHz.
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Conclusions
Ceasing the Over segmentation Problem.
Speeding up the conventional method using temporal information.
A fast VOP extraction algorithm to be used in real time video processing systems.
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Questions?
?