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Variable quality image compression system based on SPIHT. Authors: A. Jarvi, J. Lehtien, O. Nevalainen Source: Signal Processing: Image Communication 14(1999) 683-696 Date: 11 September 1999 Speaker: Ming-Ni Wu. SPIHT.
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Variable quality image compression system based on SPIHT Authors: A. Jarvi, J. Lehtien, O. Nevalainen Source: Signal Processing: Image Communication 14(1999) 683-696 Date: 11 September 1999 Speaker: Ming-Ni Wu
SPIHT • Set Partitioning In Hierarchical Trees by Said and Pearlman 1996 • a wavelet-based image compressing method • to provide better performance then original EZW(Embedded Zerotree Wavelet) • a bitplane coding method
SPIHT n: the number of significant bits in the coefficient table having the largest absolute value H: set of coordinates of all spatial orientation tree roots LSP: List of Significant pixels LIP: List of insignificant pixels LIS: List of insignificant sets type A: set of coordinates of all descendants of the node type B: set of coordinates of all descendants of the node, excluding offspring of the node
vqSPIHT • to provide better quality for some regions or details • implementation with matrix
vqSPIHT : a percentage of the wanted final output file size n: the number of significant bits in the coefficient table having the largest absolute value ROI: Region of Interest LUT: lookup table, to define whether a coefficient(i,j) contribute to any ROI or not
vqSPIHT PSM: point significance matrix 11:significant 00: insignificant 01:unknown SPLM:sub-pyramid list matrix type A: set of coordinates of all descendants of the node type B: set of coordinates of all descendants of the node, excluding offspring of the node
Test Results • The comic test image of size 420*480 with 8bpp
Test Results • The mammogram test image of size 2185*2925 with 12bpp
Test Results • Practical memory requirements of the implementation for 12MB mammogram • SPIHT : 120MB • vqSPIHT: 50MB
Conclusions • to encode different parts of an image with different bit-rates depending on their importance • to simplify the implementation of SPIHT • to reduce working storage requirements • Combine the sending of significant coefficients to sorting phase to avoid the problem of transmission interrupting