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Error Concealment for Stereoscopic Sequences ITG Fachausschusstagung 3.2, Juni 2006

Error Concealment for Stereoscopic Sequences ITG Fachausschusstagung 3.2, Juni 2006. Introduction. Monoscopic Error Concealment strategies are not well suited for stereoscopic scenario Assumtions independently coded views of a stereo image pair

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Error Concealment for Stereoscopic Sequences ITG Fachausschusstagung 3.2, Juni 2006

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  1. Error Concealment for Stereoscopic SequencesITG Fachausschusstagung 3.2, Juni 2006

  2. Introduction • Monoscopic Error Concealment strategies are not well suited for stereoscopic scenario • Assumtions • independently coded views of a stereo image pair • remaining redundancies between the channels, which can be utilized for error concealment • block based coding (16x16 blocks) Error Concealment for Stereoscopic Sequences

  3. Algorithm Overview Identification of corresponding region • feature extraction • feature matching along epipolar line • selection of matches (M-estimator/RANSAC) Projective Transformation • initial parameter set from matches • optimization by Newton Method Smoothing • only in case of discontinuities of depth Error Concealment for Stereoscopic Sequences

  4. Matching and Transformation projectivetransformation: Error Concealment for Stereoscopic Sequences

  5. Selection of feature matches • M-estimator • uses all matches with different weights • In some cases the transformation fails, because pixels from outside the image were warped into the erroneous burst. • RANSAC(random sample consensus) • uses a number of subsamples (four feature matches) • minimize the sum of squared residues of the boundary region: RANSAC yields better results than M-estimator Error Concealment for Stereoscopic Sequences

  6. Adapted Newton Method • Find the optimal transformation parameter by minimizing a cost function C(k): • b is the Border Region of the erroneous block burst Error Concealment for Stereoscopic Sequences

  7. Adapted Newton Method • Iteration step: • Problem I: Local minimum solution • Initial Parameter set is of prime importance Cost function C(k) over horizontal and vertical translation parameter Error Concealment for Stereoscopic Sequences

  8. Adapted Newton Method • Problem II: Convergence of Newton method • Successivly decreasing of border pixel size L after every minimum search Speed of convergence of the Newthon algorithm for different border sizes L Error Concealment for Stereoscopic Sequences

  9. 3D Block Smoothing • In case of great discontinuities in depth (variation of disparity) we perform a linear smoothing algorithm towards the surrounding pixel region (3D-BS) • Minimization of the intersample variance between neighboring samples and to the block borders Error Concealment for Stereoscopic Sequences

  10. HQ EC: Results / Example Error Concealment for Stereoscopic Sequences

  11. Results / Subjective Evaluation • Subjective Simulation Results: • Double Stimulus Continuous Quality Scale Method (DSCQS) as phsychovisual test with 15 subjects • Shutterglasses (StereoGraphics) DMOS Error Concealment for Stereoscopic Sequences

  12. Fast EC: Algorithm Overview • Block Search • Directional Diamond Search • SAD • Side Match Distortion Error Concealment for Stereoscopic Sequences

  13. Fast EC: Matching Example „Hall“ • SMD determined for each possible position • Position with minimum SMD selected • Block used for reconstruction Error Concealment for Stereoscopic Sequences

  14. Fast EC: Subjective Evaluation Error Concealment for Stereoscopic Sequences

  15. Simple Matching - Example • ‘Balloons’ 720x480, corrupted frame and features Error Concealment for Stereoscopic Sequences

  16. Simple Matching - Example • Reference frame (temporal) with features Error Concealment for Stereoscopic Sequences

  17. Simple Matching - Example • Reference blocks Error Concealment for Stereoscopic Sequences

  18. Simple Matching - Example • Reconstructed frame Error Concealment for Stereoscopic Sequences

  19. Publications • K. Günther, C. Clemens, and T. Sikora A Fast Displacement-Estimation Based Approach For Stereoscopic Error Concealment PCS 2004, San Francisco • C. Clemens, M. Kunter, S. Knorr, and T. Sikora: A hybrid approach for error concealment in stereoscopic images WIAMIS '04, Lissabon • M. Kunter, S. Knorr, C. Clemens, and T. Sikora: A gradient based approach for stereoscopic error concealment ICIP '04, Singapore • S. Knorr, C. Clemens, M. Kunter, and T. SikoraRobust Concealment for Erroneous Block Bursts in Stereoscopic Images3D Data Processing, Visualization, and Transmission (3DPVT'04), Thessaloniki, Greece Error Concealment for Stereoscopic Sequences

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