JPEG2000 Michael W Marcellin marcellin ece arizona edu www SPACL ece arizona edu 520 621 6190 IASTED November 2003 JPEG2000 Features Scalable code stream Progressive transmission I I I I I I I I I I I 2 Quality Resolution Spatial location Component Lossless available naturally by progression Binary as well as continuous tone imagery Random code stream access Region of interest Superior compression performance JPEG2000 Compression 3 Progression by Resolution 4 Progression by Quality 0 03125 bpp 768 1 1024 bytes 5 0 0625 bpp 384 1 2048 bytes Progression by Quality cont 0 125 bpp 192 1 4096 bytes 6 0 25 bpp 96 1 8192 bytes Progression by Quality cont Lossless 1 76 1 7 Progression by Spatial Location L 8 Progression by Component 9 Progression Order Change I 10 Progression orders can be mixed and matched within a single code stream Region of Interest 11 Comparison with JPEG 0 25 bpp 12 The JPEG2000 Algorithm 13 Color Transforms Enable Color Scalability Allowed only for three components with same I subsampling and bit depth I Applied independently to each color pixel I Resulting Y component is monochrome e g B W TV I 14 Cb Cr are chrominance components color info I Most energy is in Y Cb and Cr are highly compressible I Improves compression efficiency I More transforms allowed for Part 2 e g KLT wavelet Color Transforms cont Two color transforms are supported I Irreversible color transform ICT I I 15 I RGB to YCbCr real numbers in general I Useful for high performance lossy compression I Does not support lossless compression Reversible color transform RCT I Integer approximation of ICT I Useful for lossy and lossless compression Example RGB Images R I 16 G B Note that the color components are highly correlated Example YCbCr Images Cr I I 17 Y Cb Dynamic range of Cb and Cr is significantly reduced as compared to B and R Cb and Cr are highly compressible Wavelet Transform Enables Resolution Scalability I x k The filtering perspective h0 2 y0 n 2 g0 h1 2 y1 n 2 g1 1 D Forward Wavelet Transform 18 1 D Inverse Wavelet Transform x k 2D Transform An Example 19 Wavelet Transform Example again I 20 Same as previous chart but LH HL HH stretched for display Wavelet Transform Example Two Levels Three Resolutions 21 Wavelet Transforms in JPEG2000 Two versions I 22 I Irreversible floating point 9 7 high performance lossy I Reversible Integer 5 3 lossy and lossless I Correspondence to the ICT and RCT respectively I More flexibility in Part 2 I 9 7 can be described by either convolution or lifting I 5 3 can only be described via lifting I Boundaries are handled via symmetric extension Embedded Deadzone Quantization Enables Quality Scalability Scalar quantization with deadzone Allows real numbers to be approximated by integers I I 4 3 2 0 y q Q y sign y I I I 2 3 4 y Q 1 q sign q q r Dropping LSB of q is equivalent to doubling step size Separate stepsize allowed for each subband No quantization necessary for reversible transforms I 23 Effectively then 1 Embedded Quantization cont I I Coupled with bit plane coding for quality scalability Overly simplified More details to follow 1 4 Scale Subbands 2K 1 1 2 Scale Subbands 2K 2 2K 3 Full Scale Subbands Resolution Progressive Send quantized data in order of increasing scale 24 20 0 1 1 0 SNR Progressive Send bits in order that minimizes MSE Codeblocks within Subbands Enable Spatial Random Access 25 Shameless Advertisement I I I 26 D S Taubman and M W Marcellin JPEG2000 Image Compression Fundamentals Standards and Practice Kluwer Academic Publishers 2002 This book is intended to serve as a textbook on image compression fundamentals as well as the definitive reference on JPEG2000 Includes full source implementation of JPEG2000 Part 1 with some Part 2 extensions Interactive Browsing Demo Very large image I I 14680H x 14565W pixels I uncompressed 204 MB N JP2 file compressed to 1 5 bpp 38 MB I Demo 1 High speed communication link I Seamless delivery I I Demo 2 Low speed link I Typical phone modem speed 32 kbits sec I Use of progressive transmission readily apparent I 27 attempted display of TIF often crashes my computer Highly responsive browsing is achieved even though download of entire compressed file would require 2 2 hours
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