CV in a Nutshell (I) Yi Li inNutshell.htm

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

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?

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

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

Lighting

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

Illusion Aperture problem ment2.html ment2.html

Skeletonization

Template Matching Find transformation to align two images cost function Example: Chamfer Matching Example 2: Hough transform Example 3: Probabilistic voting

Deformable Shape matching – Shape Context Snake – Active Contour, Active Appearance Articulated objects – Scissor – Human body

Face Recognition Linear subspaces – PCA and LDA – Eigenfaces vs Fisherfaces

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