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Representation and Modeling of Natural Scenes Ying Nian Wu UCLA Department of Statistics

Representation and Modeling of Natural Scenes Ying Nian Wu UCLA Department of Statistics. http://www.stat.ucla.edu/~ywu/research/. Song Chun Zhu. Stefano Soatto. Wu, Zhu, Liu, IJCV 2000; Zhu, Liu, Wu, PAMI 2000. observed image. synthesized image. Malik and Perona, late 80s. Image I.

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Representation and Modeling of Natural Scenes Ying Nian Wu UCLA Department of Statistics

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  1. Representation and Modeling of Natural Scenes Ying Nian Wu UCLA Department of Statistics http://www.stat.ucla.edu/~ywu/research/

  2. Song Chun Zhu Stefano Soatto

  3. Wu, Zhu, Liu, IJCV 2000; Zhu, Liu, Wu, PAMI 2000 observed image synthesized image

  4. Malik and Perona, late 80s

  5. Image I Filter response Filtered image Histogram Histogram matching (Heeger and Bergen, mid 90s)

  6. Draw random samples from the Julesz ensemble Global statistical property Zhu, Liu, Wu, PAMI 2000 Julesz ensemble Image lattice Image universe

  7. Local statistical property Wu, Zhu, Liu, IJCV 2000 Large lattice Small patch Julesz ensemble Markov random field • Gibbs (1902): equivalence of ensembles • Exponential family model

  8. Iobs from a unknown W(hc) Isyn ~ W(h) with h= f Isyn with h= 1 histogram h= 7 histograms h= 2 histograms h= 4 histograms

  9. Olshausen & Field: Sparse coding Data: a collection of natural image patches Learning: basis Linear representation: Sparseness of coefficients  linear bases Mallat and Zhang: matching pursuit Candes and Donoho: curvelets

  10. Two-Level Generative Model Mixture prior for sparseness Bell & Sejnowski (96) Lewiki & Olshausen (99) Olshausen & Millman (00) Pece (01) George & McCulloch (95)

  11. Wu, Zhu, Guo, ECCV 2002. Sketch Model • Model fitting (EM-type iteration) • Estimate S based on I and Sketch Model (MCMC) • Fit Sketch Model on S • Simplification • Estimate S from I using matching pursuit (Mallat & Zhang) • Fit Sketch Model on S (ignoring c and e)

  12. Math representations of sketch List: Bit-map: Causal model for sketch Pairwise interactions

  13. Soatto,Doretto,Wu, ICCV 2001

  14. Soatto,Doretto,Wu, ICCV 2001 • Modeling dynamic scenes • Data: • Model: time series • Representation: principal components (Fourier bases) • Autoregressive model Fourier’s solution to heat equation

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