Transcript A Quick Illustration of JPEG 2000

A Quick Illustration of
JPEG 2000
Presented by
Kim-Huei Low
Chun Data Fok
Overview
Introduction
 Approach
 Illustration



Figure:
Picture of Data using
JPEG (75%
compression ratio,
15KB)
Annex B-H
Comparison with JPEG
Conclusion
 References
 Questions

Figure:
Picture of Kim
using J2K
(0.5bpp,
3.8KB)
Introduction

JPEG 2000
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Drafted by the international JPEG (Joint Bilevel Image Experts Group) and JBIG (Joint
Photographic Experts Group) groups.
Replaces traditional JPEG.
Focuses on hardware implementation.
Our goal


Present a simplified version of the standard.
Give new users a grasp of JPEG 2000.
Approach



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Follow the same order
as the standard.
Explain the
background.
Illustrate each feature.
Discuss its
applications.
List the pros and cons.
Will skip Annex A, C
and D.

Feature wise, it’s not
important.
Figure: 0.25bpp J2K Image (11KB);
Raw Image’s Size is 1MB
Illustration: Annex B

Tile division

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Large images
can be broken
down into
smaller pieces,
called tiles.
Tiles are
processed
independently
Figure: Original DWT
Figure: Sub-band Selection
Figure: Precinct Selection
Figure: Code-block Selection
Illustration: Annex B

Progression Order

Layer or Resolution Progressive
Figure: 1bpp, 0.5bpp, 0.05bpp and 0.01bpp J2K Image with Layer or Resolution Progression.
Illustration: Annex B

Progression Order

Component Progressive
Figure: 1bpp, 0.5bpp, 0.1bpp and 0.01bpp J2K Image with Component Progression.
Illustration: Annex B

Progression Order

Position Progressive
Figure: 1bpp, 0.5bpp and 0.1bpp J2K Image with Position Progression.
Illustration: Annex E

Quantization

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Reversible vs Irreversible
Target bit rate=0.5 bpp
Step size=1
Figure: Reversible Quantization
(16KB)
Figure: Irreversible Explicit
Quantization (868B)
Figure: Irreversible Implicit
Quantization (787B)
Illustration: Annex E

Irreversible Explicit Quantization
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Target bit rate=0.5 bpp
Different step size
Figure: Step Size 1 (868B)
Figure: Step Size 0.1 (11.9KB)
Figure: Step Size 0.0078 (16.3KB)
Illustration: Annex E
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Irreversible Implicit Quantization
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Target bit rate=0.5 bpp
Different step size
Figure: Step Size 1 (787B)
Figure: Step Size 0.1 (11.7KB)
Figure: Step Size 0.0078 (16.3KB)
Illustration: Annex F
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Discrete Wavelet Transformation (DWT)
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Reversible = 5x3 filter (lossless compression)
Irreversible = 9x7 filter (efficient lossy compression)
Illustration: Annex F
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Lossless vs Lossy DWT
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Different decomposition level
Higher decomposition levels – higher overhead
Figure: Lossless,
NL=14 (275KB)
Figure: Lossy,
NL=14 (99KB)
Figure: Lossless,
NL=3 (274KB)
Figure: Lossy, NL=3
(98KB)
Illustration: Annex F
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Discard of high frequency sub-bands
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High compression, smaller file size
Same quality
Amortize decomposition level overhead
Optimal/Ideal: Encode up to the last visually
distinguishable low frequency sub-band
Figure: NL=3,
8.3636bpp (274KB)
Figure: NL=14,
0.9948bpp (32.6KB)
Illustration: Annex G
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DC Level Shifting
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Similar to JPEG
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New pixel value = Pixel value - 128
Component Decorrelating Transformation
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Reversible vs Irreversible
Figure: Raw Image; 0.035bpp J2K Image with RCT; 0.035bpp J2K Image with ICT
Illustration: Annex H
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Region of Interest (ROI) Encoding
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Efficient use of bit rate
If bit rate is too low, encoding without ROI
may look better overall
Figure: Raw Image; 0.07bpp J2K Image with ROI; 0.07bpp J2K Image without ROI
Illustration: Comparison of JPEG 2000
with JPEG

10 test images, 50+ compression ratios
PSNR vs File Size



255 MN


PSNR  10 log10 
| g ( x , y )  f ( x, y ) | 


 xy

PSNR vs File Size
Figure: PSNR Curve
25
20
PSNR (dB)

15
JPEG
JPEG 2000
10
5
0
0
10000
20000
30000
40000
50000
File Size (bytes)
60000
70000
80000
Illustration: Comparison of JPEG 2000
with JPEG
Much smaller files
 Much better quality

Figure: 0.08bpp J2K Image (8KB); 0.1563bpp JPEG Image (16KB);
Conclusion
Excellent compression rate
 Fully exploits the advantage of DWT
 Capable of handling extremely large
images
 Lots of user-selectable features
 Efficient for hardware implementation
 Most advanced image compression
standard
 Implication of MPEG 2000?

References

International Telecommunication Union (ITU),
International Organization for Standardization
(ISO), “JPEG 2000 Implementation in Java,”
http://jpeg2000.epfl.ch, October 16th, 2003.

ISO/IEC JTCI/SC29 WGI, JPEG 2000 Editor
Martin Boliek, Charilaos Christopoulos, Eric
Majani, “JPEG 2000 Image Coding System,”
http://www.jpeg.org/CDs15444.html, March
16th, 2000.