A Fast and Efficient VOP Extraction Method Based on Watershed Segmentation Alireza Tavakkoli Dr. Shohreh Kasaei Gholamreza Amayeh Sharif University of Technology

2 Outline Problem Definition. Literature Review. Proposed Method. Performance Analysis. Conclusions.

3 Content-Based Functionalities in Video User Interaction. Very Low Bit-rate Video Compression. Video Indexing. Object-Based Video Coding Systems: MPEG 4. H.263.

4 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.

5 VOP Extraction Spatio-Temporal Segmentation: Spatial Segmentation: Watershed Segmentation. Temporal Information: Motion Detection. Change Detection Masks.

6 Watershed Segmentation Rain Fall Simulation: Immersion Simulation: Vincent & Soille (1991).

7 Drawbacks of Watershed Segmentation Results in over segmentation. Very time consuming. Solutions: Region Merging Techniques. Predictive Watershed.

8 Over Segmentation

9 Region Merging Using Modified Gradient

10 Preparing Image for Watershed Segmentation

11 Resulting Watershed Segmentation

12 Predictive Watershed Some Definitions:

13 Prediction of Watershed

14 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.

15 CDM and Noise Difference Noise: Gaussian Noise: Due to intensity changes. Can be reduced by a Hypothesis test. Hypothesis test: Noise if H 0 True. Object if H 1 True.

16 Region Labeling Method Hypothesis Test

17 Watershed Update

18 VOP Extraction Algorithm

19 Experimental Results

20 Experimental Results (Contd.)

21 Experimental Results (Contd.)

22 Experimental Results (Contd.)

23 Experimental Results (Contd.) Seq. Name FrameWatersh ed Method Number of Pixels Number of Regions Time (msc.) ≈ Hall& Monitor F-FrameSoile Proposed P-FrameProposed Walking Daniel F-FrameSoile Proposed P-FrameProposed Matlab 6.2 Software, Pentium 4, 2.0GHz.

24 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.

25 Questions? ?