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Random Walks on Graphs to Model Saliency in Images. Viswanath Gopalakrishnan Yiqun Hu Deepu Rajan School of Computer Engineering Nanyang Technological University, Singapore 639798 CVPR2009 Reporter: Chia-Hao Hsieh Date: 2010/05/04. Outline. Introduction Methods Experimental results.
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Random Walks on Graphs to Model Saliency in Images ViswanathGopalakrishnanYiqunHuDeepuRajan School of Computer Engineering Nanyang Technological University, Singapore 639798 CVPR2009 Reporter: Chia-Hao Hsieh Date: 2010/05/04
Outline • Introduction • Methods • Experimental results
Introduction • Salient region detection based on Markov random walks • Combine global/local property • Seeded salient region identification
Methods • Graph representation • Nodes, Edges • Finding the most salient node
Graph Representation • Node: patches of size 8x8 on the image • Edge: connection between the nodes • Feature: color/orientation • Cb, Cr • Orientation histogram entropy at 5 different scales HP(θi) is the histogram value of the ith orientation bin corresponding to the orientation θi Node feature vector
Finding the Most Salient Node • Most salient: globally pop-out (isolated) • A random walker take more time to reach • If on a compact object, a random walker take less time to reach on a k-regular graph
Background Nodes • Inhomogeneous background • Goal: Capture as much of these variations as possible by locating at least one background node in each of such regions • Maximizing the distance to the most salient node, also maximizing the distance between background nodes
Seeded Salient Region Extraction • If global only • Erroneously classify to salient region • If local only • Spatially close to a salient node • Linearly combine global and local feature
Experimental results Comparison of precision, recall, f-Measure Failure examples