Download - Volumetric Image Compression with CS-EBCOT

VOLUMETRIC VOLUMETRIC IMAGE IMAGE

COMPRESSION COMPRESSION WITH CSWITH CS--EBCOTEBCOT

Xavier Giró i NietoPhilippe Salembier Universitat Politècnica de Catalunya - ETSETB

Peter SchelkensJan CornelisVrije Universiteit Brussels - ETRO

Xavier Giró i Nieto ([email protected]) 2

VOLUMETRIC IMAGECOMPRESSION

WITH CS-EBCOTINTRODUCTIONINTRODUCTION

Encoder Embedded coder Embedded coder

Bit-stream Structured bit-stream Structured bit-stream

Image compression techniques

1st generationstrcuture derived

from coderEx. JPEG

2nd generationstrcuture derived

from coder

3rd generationabstract interface

between coder andbit-stream structures



WITH CS-EBCOTINTRODUCTIONINTRODUCTION

Embedded coder

Structured bit-stream

3rd generationabstract interface

between coder andbit-stream structures

• 3rd generation coders (JPEG200)- support for lossles and lossy- enable rate scalability, quality and resolution scalability

• volumetric images ?(Ex. medical)

• 2D techniques slice by sliceexploit correlation only throughX and Y axis


adapt the VM 6.0 EBCOT coder to support volumetric images including a Cube-Splitting front end.study the performance of– CS-EBCOT for lossless and lossy coding– new wavelet filters– 3D Morton scanning pattern– models of a context-based adaptive arithmetic

coder


WITH CS-EBCOTTARGETSTARGETS


CS-EBCOT codec is – always outperforming Cube-Splitting and

3D SPIHT coding engine in lossless coding– giving good results for lossy coding,

especially at low bit-rates when comparing with PSNR

– giving the best visual quality for lossy coding


WITH CS-EBCOTRESULTSRESULTS



WITH CS-EBCOTGENERAL SCHEMEGENERAL SCHEME

3D wavelettransform Tier 1 Tier 2

INPUT IMAGE-raw data from 1 to 32 bits-medical, multispectral, ...

3D EBCOT CODER



WITH CS-EBCOT3D WAVELET3D WAVELETL

H

2

2

L

H

2

2x

d1

d2

s2

s2 d2

Level 1 (Finest level)Level 2 (Coarsest level)

d1

- apply the wavelet transformin the three spatial directions

- subband organization





3D EBCOT CODER

WAVELET COEFFICIENTS-distributed in subbands and decomposition levels

INPUTIMAGE



WITH CS-EBCOTCODEBLOCKSCODEBLOCKS

HLL HHL

HLL HHL

LLL LHLLHL

LLH LHH

HHH

LLH LHH

CODING UNIT:the codeblock



WITH CS-EBCOTCODEBLOCKSCODEBLOCKSCODING UNIT:the codeblock

• each codeblock iscoded independently• zero coefficientsare added whenoutcoming the borders





3D EBCOT CODER

TIER 1-embedded block coding-operates on block samples

INPUTIMAGE

WAVELETCOEFFICIENTS

...

CODEBLOCKS



WITH CS-EBCOTEBCOT TIER 1EBCOT TIER 1Octree cube

spliiting

Fractionalbit-planecodingCODEBLOCK

OCTREE CUBE SPLITTING-identifies subblocks in the codeblockwhich contain significant information for present bit-plane

FOR EACH BIT-PLANE



WITH CS-EBCOTOCTREE CODINGOCTREE CODING

SGN

SGNNSNSNSNSNSNSNS

SGNNSNSNSNSNSNSNS

SGN = SignificantNS = Non-significant




spliting


FOR EACH BIT-PLANE

SIGNIFICANTSUBBLOCK

FRACTIONAL BIT-PLANE CODING• four context-based coding operations • three coding passes

• Significance Propagation• Magnitude Refinement• Normalization



WITH CS-EBCOTSCANNINGSCANNING

x

yz

2D JPEG2000 slice by slice



WITH CS-EBCOTSCANNINGSCANNINGMorton scanning pattern

2D Morton 3D Morton x

yz



WITH CS-EBCOT3D CONTEXTS3D CONTEXTS

• four coding operations:- Run-Length Coding (RLC)- Zero Coding (ZC)- Sign coding (SC)- Magnitude Refinement Coding (MR)

• original 2D contexts wereadapted to 3D (more complex)

• from the 8 neighbours in 2D to26 neighbours with 3 categoriesin 3D

closer



WITH CS-EBCOTCODING PASSESCODING PASSES3 coding passes are applied in every bit-plane

• SIGNIFICANCE PASSNeighbours of already previous significant coefficients

• MAGNITUDE REFINEMENT PASSCoefficients already marked as asignificant

• NORMALIZATION PASSRest of the coefficients



WITH CS-EBCOTCODING PASSESCODING PASSESbit-plane

x

y

presentbit-plane

on a 2D image

Significance passMagnitude refinement passNormalization passnot processed in the present bit-plane



WITH CS-EBCOTTRUNCATIONTRUNCATION

O[pmax] +P[pmax,3] P[pmax-1,1] P[pmax-1,2] O[pmax-1] +

P[pmax-1,3]O[pmax-1] +P[pmax-1,3]P[0,2]P[0,1]

rate

distortion

O[pmax] +P[pmax,3] P[pmax-1,1] P[pmax-1,2] O[pmax-1] +

P[pmax-1,3]O[pmax-1] +P[pmax-1,3]P[0,2]P[0,1]

Where to truncate ?

one bit-stream foreach code block




spliting


FOR EACH BIT-PLANE

SIGNIFICANTSUBBLOCK

EMBEDDEDBLOCK

STREAM

EMBEDDED BLOCK BIT-STREAM• one bit-stream for each codeblock• one possible truncation point associated to the end of each pass• a distortion associated to each truncation pass





3D EBCOT CODER

TIER 2-coding of block contributions to each quality layer-operates on block summary info

INPUTIMAGE

WAVELETCOEFFICIENTS

...

CODEBLOCKS

EMBED.STREAM



WITH CS-EBCOTEBCOT TIER 2EBCOT TIER 2• T2 generates a packet for each resolution level in each quality layer

Body (code bytes)Header

FOR EACH CODEBLOCK-first inclusion layer (tag tree)-maximum bit-depth (tag tree)-number of new coding passes included in body-number of new bytes included in the body



WITH CS-EBCOTEBCOT TIER 2EBCOT TIER 2layer 1 layer 2 layer Λ -1 layer Λ

resolution L resolution L-1 resolution 1 resolution 0

LLL HLL LHL HHL LLH HLH LHH HHH

header code bytes

inclusion layer insignificant msbs number of passes number of bytes

block 0 block 1 block 2 block N





3D EBCOT CODER

INPUTIMAGE

WAVELETCOEFFICIENTS

...

CODEBLOCKS

EMBED.STREAM

COMPRESSEDFILE


further experiments with size of codeblocksimprove arithmetic coder


WITH CS-EBCOTFUTURE WORKFUTURE WORK


JPEG2000 principles are fully aplicable for 3D imagesoctree front end is a valuable toolInteger 5x11 is the best integer kernel for lossy and lossless compressionno gain in using Morton scanning


WITH CS-EBCOTCONCLUSIONSCONCLUSIONS