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Wyner-Ziv Coding of Light Fields for Random Access

Wyner-Ziv Coding of Light Fields for Random Access. Overview. Light fields Predictive coding and random access Wyner-Ziv coding for light fields Simulation results. What is a Light Field?.

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Wyner-Ziv Coding of Light Fields for Random Access

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  1. Wyner-Ziv Coding of Light Fields for Random Access

  2. Overview • Light fields • Predictive coding and random access • Wyner-Ziv coding for light fields • Simulation results

  3. What is a Light Field? A 4-D data set for image-based rendering,typically parameterized as a 2-D set of images. [Levoy and Hanrahan, 1996] [Gortler et al., 1996]

  4. decoded images level 0 level 1 level 2 desired image geometry model image 2 image 1 Light Field Coding using Prediction hierarchical prediction [Magnor and Girod, 2000] [Ramanathan et al., 2002][Chang et al., 2003]

  5. Rendering a Single Novel View Garfield light field How do we perform better than intracoding?

  6. Encoder Decoder Statistically dependent Wyner-Ziv Coding [Wyner and Ziv, 1976] Lossy compression with decoder side information

  7. Wyner-Ziv image Key image Wyner-Ziv Coding of Light Fields At the decoder, side information for decoding Wyner-Ziv image is rendered from available key images • Better rate-distortion performance than intracoding [Zhu, Aaron, Girod, 2003] • Similar work by [Jagmohan, Sehgal, Ahuja, 2003]

  8. bit-plane 2 bit-plane 1 Wyner-Ziv DCT Light Field Codec WZ image Decoded WZ image W Shape processing IDCT DCT Xk Xk’ qk qk’ Turbo Encoder Reconstruction level Quantizer Extract bit-planes Turbo Decoder … bit-plane Mk Side information Yk For each transform band k DCT Shape processing Rendering Key image Shape-adaptive decoding Shape-adaptive Intracoding K K’

  9. R-D Performance for WZ images Garfield light field 288 images each at 144x192 pixels Hemispherical camera setting with 8 rows and 32 columns Half of the images are WZ images

  10. 25% 2 dB Rendering a Single Novel View Garfield light field data set R-D Performance averaged over 20 novel views. Each novel view is rendered from closest 4 images.

  11. Sample Rendered View Intracoding 1.5 bpop, 33.8 dB Original Wyner-Ziv coding 1.4 bpop, 36.2 dB

  12. Summary • Wyner-Ziv coding of light field images for random access and compression efficiency • Up to 2 dB PSNR improvement over intracoding for rendering novel views • Single representation of data set multiple representation solution [Ramanathan and Girod, MMSP 2004]

  13. Sample Rendered View Intracoding 1.6 bpop, 33.7 dB Original Wyner-Ziv coding 1.9 bpop, 36.6 dB

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