A Quick Illustration of JPEG 2000 Presented by Kim-Huei Low Chun Data Fok

Overview  Introduction  Approach  Illustration Annex B-H Comparison with JPEG  Conclusion  References  Questions Figure: Picture of Data using JPEG (75% compression ratio, 15KB) Figure: Picture of Kim using J2K (0.5bpp, 3.8KB)

Introduction  JPEG 2000 Drafted by the international JPEG (Joint Bi- level 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  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 Large images can be broken down into smaller pieces, called tiles. Tiles are processed independently Figure: Original DWTFigure: Precinct Selection Figure: Sub-band SelectionFigure: 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 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 Target bit rate=0.5 bpp Different step size Figure: Step Size 1 (868B)Figure: Step Size 0.1 (11.9KB)Figure: Step Size (16.3KB)

Illustration: Annex E  Irreversible Implicit Quantization Target bit rate=0.5 bpp Different step size Figure: Step Size 1 (787B)Figure: Step Size 0.1 (11.7KB)Figure: Step Size (16.3KB)

Illustration: Annex F  Discrete Wavelet Transformation (DWT) Reversible = 5x3 filter (lossless compression) Irreversible = 9x7 filter (efficient lossy compression)

Illustration: Annex F  Lossless vs Lossy DWT Different decomposition level Higher decomposition levels – higher overhead Figure: Lossless, N L =14 (275KB) Figure: Lossy, N L =14 (99KB) Figure: Lossless, N L =3 (274KB) Figure: Lossy, N L =3 (98KB)

Illustration: Annex F  Discard of high frequency sub-bands 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: N L =3, bpp (274KB) Figure: N L =14, bpp (32.6KB)

Illustration: Annex G  DC Level Shifting Similar to JPEG  New pixel value = Pixel value  Component Decorrelating Transformation Reversible vs Irreversible Figure: Raw Image; 0.035bpp J2K Image with RCT; 0.035bpp J2K Image with ICT

Illustration: Annex H  Region of Interest (ROI) Encoding 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 Figure: PSNR Curve

Illustration: Comparison of JPEG 2000 with JPEG  Much smaller files  Much better quality Figure: 0.08bpp J2K Image (8KB); bpp 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,” October 16th,  ISO/IEC JTCI/SC29 WGI, JPEG 2000 Editor Martin Boliek, Charilaos Christopoulos, Eric Majani, “JPEG 2000 Image Coding System,” March 16th,