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Image Pyramids

Image Pyramids. Computer Vision, winter 2012-13 CS Department, Technion. Topics. The Gaussian Pyramid The Laplacian Pyramid Applications: Pattern Matching Coding (Compression) Enhancement Blending. Gaussian Pyramid. Gaussian Pyramid. Approximation filter is not Gaussian

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Image Pyramids

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  1. Image Pyramids Computer Vision, winter 2012-13 CS Department, Technion

  2. Topics • The Gaussian Pyramid • The Laplacian Pyramid • Applications: • Pattern Matching • Coding (Compression) • Enhancement • Blending

  3. Gaussian Pyramid

  4. Gaussian Pyramid • Approximation filter is not Gaussian • A 5 tap binomial kernel: • 2D extension:

  5. Pattern Matching

  6. Laplacian Pyramid

  7. Laplacian Pyramid • Approximation of the Laplacian of each scale • Constructed by Difference of Gaussian (DoG) layers

  8. LaplacianPyramid

  9. Image Coding

  10. Enhancement

  11. Enhancement

  12. Pyramid Blending

  13. Step I - Create Blend Masks

  14. Step II Blend 1 Blend 1 Mask Blend 2 Blend 2 Mask • Weighted sum over each Laplacianpyramid scale (of the images) independently • Gaussian pyramid of masks, or simple resizing of masks to correct dimensions

  15. Step III • Standard Laplacian pyramid reconstruction of blended scales

  16. Implementation Issues • Image registration • Feathering • Over/under flows outside [0,1] • MATLAB function: impyramid() • Only Gaussian pyramid • ‘reduce’ or ‘expand’ modes • MATLAB function: imresize() • Useful for masks resizing

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