Notes
Slide Show
Outline
1
Filtering
    • An image as a function
    • Digital vs. continuous images
    • Image transformation:  range vs. domain
    • Types of noise
    • LSI filters
      • cross-correlation and convolution
      • properties of LSI filters
      • mean, Gaussian, bilinear filters
    • Median filtering
    • Image scaling
    • Image resampling
    • Aliasing
    • Gaussian pyramids
    • Bilinear Filters
2
Edge detection
    • What is an edge and where does it come from
    • Edge detection by differentiation
    • Image gradients
      • continuous and discrete
      • filters (e.g., Sobel operator)
    • Effects of noise on gradients
    • Derivative theorem of convolution
    • Derivative of Gaussian (DoG) operator
    • Laplacian operator
      • Laplacian of Gaussian (LoG)
    • Canny edge detector (basic idea)
      • Effects of varying sigma parameter
    • Approximating an LoG by subtraction
    • Hough Transform (lines, circles, “generalized” (from midterm))


3
Segmentation
    • Graph representation of an image
    • Intelligent scissors method
    • Image histogram
    • K-means clustering
    • Morphological operations
      • dilation, erosion, closing, opening
    • Normalized cuts method
    • Matting—separate foreground from background (basic idea)




4
Motion
    • Optical flow problem definition
    • Aperture problem and how it arises
    • Assumptions
      • Brightness constancy, small motion, smoothness
    • Derivation of optical flow constraint equation
    • Lukas-Kanade equation
      • Derivation
      • Conditions for solvability
      • meanings of eigenvalues and eigenvectors
    • Iterative refinement
      • Newton’s method
      • Coarse-to-fine flow estimation
    • Feature tracking
      • Harris feature detector
      • L-K vs. discrete search method
5
Projection
    • Properties of a pinhole camera
      • effects of aperture size
    • Properties of lens-based cameras
      • focal point, optical center, aperture
      • thin lens equation
      • depth of field
      • circle of confusion
    • Modeling projection
      • homogeneous coordinates
      • projection matrix and its elements
      • types of projections (orthographic, perspective)
    • Camera parameters
      • intrinsics, extrinsics
      • types of distortion and how to model

6
Mosaics
    • Image alignment (using Lucas-Kanade)
    • Image reprojection
      • homographies
      • cylindrical projection
    • Creating cylindrical panoramas
    • Image blending
    • Image warping
      • forward warping
      • inverse warping
7
Projective geometry
    • Homogeneous coordinates and their geometric intuition
    • Homographies
    • Points and lines in projective space
      • projective operations: line intersection, line containing two points
      • ideal points and lines (at infinity)
    • Vanishing points and lines and how to compute them
    • Single view measurement
      • within a reference plane
      • height
    • Cross ratio
    • Camera calibration
      • using vanishing points
      • direct linear method


8
Stereo
  • Things to take away from this lecture
    • Cues for 3D inference, shape from X (basic idea)
    • Epipolar geometry
    • Stereo image rectification
    • Stereo matching
      • window-based epipolar search
      • effect of window size
      • sources of error
    • Active stereo (basic idea)
      • structured light
      • laser scanning
9
Multiview stereo
    • Baseline tradeoff
    • Multibaseline stereo approach
    • Voxel coloring problem
    • Volume intersection algorithm
    • Voxel coloring algorithm
10
Light, perception, and reflection
    • Light field, plenoptic function
    • Light as EMR spectrum
    • Perception
      • color constancy, color contrast
      • adaptation
      • the retina:  rods, cones (S, M, L), fovea
      • what is color
        • response function, filters the spectrum
        • metamers
    • Finding camera response function (basic idea, not details)
    • Materials and reflection
      • what happens when light hits a surface
      • BRDF
      • diffuse (Lambertian) reflection
      • specular reflection
      • Phong reflection model
      • measuring the BRDF (basic idea)
11
Recognition
    • Classifiers
    • Probabilistic classification
      • decision boundaries
      • learning PDF’s from training images
      • Bayesian estimation
    • Principle component analysis
    • Eigenfaces algorithm
      • use for face recognition
      • use for face detection
12
Texture  (not on exam!!)
    • Markov chains
    • Text synthesis algorithm
    • Markov random field (MRF)
    • Texture synthesis algorithm (basic idea)