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1st Day. Lecture 1: Intro. Goal of Vision. To understand and interpret the image. Images consist of many different patterns – grass, faces, crowds. Vision is easy for Humans. Because a very large part of our brain does vision. Half the Cortex does Vision.
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1st Day Lecture 1: Intro
Goal of Vision • To understand and interpret the image. • Images consist of many different patterns – grass, faces, crowds.
Vision is easy for Humans • Because a very large part of our brain does vision. • Half the Cortex does Vision. • (Much more than does mathematics or computer science or other ‘high level’ tasks.)
Vision is very difficult • Because images are complex and ambiguous. • Left panels (top) shows two bicycles • Left panels (bottom) show intensity plots I(i,j).
Vision as Decoding • Vision is an Inverse Inference Problem
Bayes Theorem. • Bayes (left) uses prior knowledge to resolve ambiguity (right).
Statistics of Image Gradients • Left: Everywhere. Right: On and Off Edges.
Edges: Sowerby Dataset • Top: Example of Images and groundtruth • Bottom: Canny (left), Statistical method (center). • Loglikelihood ratios (right)
Edges: Combing Scales • Results: Chernoff performance measures (risk). • Triangles (grad I). Cross (Harris-Nitzberg).
Edges: Combining Directions • Results using combinations of oriented filters (Gabors).
Edge Detection is Hard • Distributions overlap: ROC curves.
Steepest Descent and Variations • Steepest Descent and Discrete Iterative.
Manhattan world • The world has Manhattan structure. • And humans make mistakes when it does not. • Identical twins in Ames room.
Geometry • Projection and Vanishing Points
Manhattan Results • Good results for Indoor Images
Manhattan Images • Results for City Scenes
Manhattan Countryside • Some images in the country also have Manhattan structure.
Non-Manhattan Images • Some images are not Manhattan – verify by model selection: compare P_{man} to P_{null}
Lecture 6 • Image Classification – independent.
Sowerby and San Francisco • Examples.
Results: • Color only (left). Texture only (right). Sowerby only.
Results: • Color and Texture: Sowery (left), San Francisco (Right).
Examples. • Sowerby:
Examples • San Francisco
Medical Applications • Apply similar ideas to medical images. • Tumor detection.