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CV in a Nutshell (I)

CV in a Nutshell (I). Yi Li http://users.cecs.anu.edu.au/~yili/CVinNutshell.htm. Outline. Introduction Image Formation Early vision Cognition in psychology Face recognition (I). Paper discussion (1). Recognition by Components: Segmentation: blocks, cylinders, wedges, cones

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CV in a Nutshell (I)

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  1. CV in a Nutshell (I) Yi Li http://users.cecs.anu.edu.au/~yili/CVinNutshell.htm

  2. Outline • Introduction • Image Formation • Early vision • Cognition in psychology • Face recognition (I)

  3. Paper discussion (1) • Recognition by Components: • Segmentation: blocks, cylinders, wedges, cones • Curvature, collinearity, symmetry, parallel • Contour, surface, texture • Occlusion • Top-down or bottom-up? • Relation: pairwise? http://euron.upc.es/dbtm/show_image.php?id=36

  4. Paper discussion (2) • Face Recognition • extremely low-resolution images (Yang and Ma) • Occlusion (sparse) • Component vshollistic • Context! • Facial expression (Cohn) • Illumination (Basri and Jacobs) • Specialized (Martinez)

  5. Image Formation • Geometry • image plane • projection • Physics of light • Brightness / Illumination • Light source • Lambertian • scattered such that the apparent brightness of the surface to an observer is the same regardless of the observer's angle of view (wiki) nikonweb.com

  6. Lighting http://www.cs.umd.edu/~djacobs/CMSC828/Lighting.pdf

  7. Early Vision • Early year of computer vision • David Marr (Psychologist, MIT) • Azriel Rosenfeld (Mathematician, Maryland) • Takeo Kanade (Engineer, CMU) • Visual path • How early? • Recognition? • Saliency / gist scienceblogs.com http://i.neoseeker.com/mgv/436139-Triforce%20of%20Wisdom/139/15/lizard_display.jpg

  8. Illusion • Aperture problem • http://www.cfar.umd.edu/~fer/optical/movement2.html • http://www.michaelbach.de/ot/

  9. Skeletonization http://www.inf.u-szeged.hu/~palagyi/skel/skel.html

  10. Template Matching • Find transformation to align two images • cost function • Example: Chamfer Matching • Example 2: Hough transform • Example 3: Probabilistic voting http://www.gavrila.net/Research/Chamfer_System/chamfer_system.html

  11. Deformable • Shape matching • Shape Context • Snake • Active Contour, Active Appearance • Articulated objects • Scissor • Human body

  12. Face Recognition • Linear subspaces • PCA and LDA • EigenfacesvsFisherfaces http://www.cs.umd.edu/~djacobs/CMSC828/LinearSubspacesGeometry.pdf

  13. Q/A • Introduction • Image Formation • Early vision • Cognition in psychology • Face recognition (I)

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