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Explore GrabCut, an interactive tool for accurate foreground extraction. Learn about its use of iterated graph cuts for segmentation, understanding the magic behind its intelligent scissors and color modeling for precise results.
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GrabCutInteractive Foreground Extraction using Iterated Graph CutsCarsten RotherVladimir Kolmogorov Andrew BlakeMicrosoft Research Cambridge-UK
GrabCut – Interactive Foreground Extraction1 Photomontage
GrabCut – Interactive Foreground Extraction2 Problem Fast & Accurate ?
GrabCut – Interactive Foreground Extraction3 What GrabCut does Magic Wand(198?) Intelligent ScissorsMortensen and Barrett (1995) GrabCut User Input Result Regions Regions & Boundary Boundary
GrabCut – Interactive Foreground Extraction4 Framework Input: Image Output: Segmentation Parameters:Colour ,Coherence Energy: Optimization:
Foreground (source) Min Cut Background(sink) Cut: separating source and sink; Energy: collection of edges Min Cut: Global minimal enegry in polynomial time GrabCut – Interactive Foreground Extraction5 Graph CutsBoykov and Jolly (2001) Image
GrabCut – Interactive Foreground Extraction6 Iterated Graph Cut ? User Initialisation Graph cuts to infer the segmentation K-means for learning colour distributions
GrabCut – Interactive Foreground Extraction7 Iterated Graph Cuts Guaranteed toconverge 1 3 4 2 Result Energy after each Iteration
GrabCut – Interactive Foreground Extraction8 Colour Model Gaussian Mixture Model (typically 5-8 components) R R Iterated graph cut Foreground &Background Foreground G Background G Background
Blake et al. (2004):Learn jointly GrabCut – Interactive Foreground Extraction9 Coherence Model An object is a coherent set of pixels:
GrabCut – Interactive Foreground Extraction10 Moderately straightforward examples … GrabCut completes automatically
GrabCut – Interactive Foreground Extraction11 Difficult Examples Camouflage & Low Contrast Fine structure No telepathy Initial Rectangle InitialResult
GrabCut – Interactive Foreground Extraction12 Evaluation – Labelled Database Available online: http://research.microsoft.com/vision/cambridge/segmentation/
Error Rate: 0.72% GrabCut – Interactive Foreground Extraction13 Comparison Boykov and Jolly (2001) GrabCut User Input Result Error Rate: 1.87% Error Rate: 1.81% Error Rate: 1.32% Error Rate: 1.25% Error Rate: 0.72%
GrabCut – Interactive Foreground Extraction22 Summary Intelligent Scissors Mortensen and Barrett (1995) LazySnappingLi et al. (2004) Graph Cuts Boykov and Jolly (2001) Magic Wand (198?) GrabCutRother et al. (2004)