Effects of Post-processing on Background Subtraction Algorithms
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Presentation Transcript
Effects of Post-processing on Background Subtraction Algorithms Donovan Parks
Outline • What is background subtraction? • Project motivation • How is BGS performed and what makes it difficult? • Project goals and results • Concluding remarks
What is background subtraction? • Real-time method for identifying moving foreground objects within a video
Project motivation • BGS is an important low-level step in many computer vision applications: • Video surveillance • Traffic monitoring • FG/BG segmentation • My interest is in using BGS to extract human silhouettes for pose estimation • How “good” are the obtained silhouettes in unconstrained environment? Images from: Sminchisescu and Telea, “Human Pose Estimation from Silhouettes”, 2002.
How is BGS performed? • Static frame differencing • BG model = first frame of video
What makes BGS difficult? • Moving background elements:
What makes BGS difficult? • Shadows:
Shadow removal • Shadows have little effect on chromaticity, but reduce luminosity
What makes BGS difficult? • Ghosting:
Ghost detection via optical flow • Low optical flow = ghost!
What else makes BGS difficult? • FG/BG blending
Project goals • Evaluate a selection of state-of-the-art background subtraction algorithms • Considering 10 algorithms in all • Analyze how post-processing influences the performance of these algorithms • Shadow removal • Optical flow testing • Morphological “cleaning” • Area thresholding
Conclusions • Many factors which make BGS difficult • Post-processing can significantly improve results • Results not as “clean” as more computationally expensive approaches
Questions? Thank you.