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Layered Coding. Basic Overview. Outline. Pyramidal Coding Scalability in the Standard Codecs Layered Coding with Wavelets Conclusion. Laplacian w/ Gaussian Pyramids. Laplacian w/ DCT Coefficient Pyramids. DCT Pyramid Example. Figure 7.5. Reconstruction Data for Fig. 7.5.
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Layered Coding Basic Overview
Outline • Pyramidal Coding • Scalability in the Standard Codecs • Layered Coding with Wavelets • Conclusion
DCT Pyramid Example • Figure 7.5
Scalability in the Standard Codecs • Data Partitioning • Signal-to-Noise Ratio (SNR) • Spatial • Temporal
Scalability Applications • Data Partitioning • Video of ATM networks • SNR • Transmission of video at different qualities • Video on demand, simultaneous TV and enhanced TV • Video over high packet loss networks (Internet) • Spatial Scalability • Internetworking between two different standards • Simulcasting of drift-free video (TV & HDTV)
Scalability Applications • Spatial Scalability (continued) • Reception of low spatial resolution pictures over mobile networks • Temporal Scalability • Migration to HDTV from current interlaced • Internetworking between mobile and fixed networks
Layered Coding with Wavelets • Growing interest due to new efficient coding techniques (Embedded Zero-tree Wavelets, or EZW) • Accepted for coding of still images • MPEG-4 and JPEG 2000 • Predicted to continues in growth
Discrete Wavelet Transform • Split signal spectrum into several frequency bands analysis filters Figs. 7.27, 7.28, 7.29
Higher Order Systems Multiple wavelet transform coding by means of repeated two-band splits
Further Considerations • Wavelet Example – Fig. 7.32 • Zero-Tree Coding – Fig. 7.34 • Quad-Tree Representation • Bands look like scaled versions of each other • Lower bands have 0.25 dimension of higher
Conclusion • Layered coding facilitates • Error protection • Efficient use of resources • Multiple services • Customer satisfaction