JPEG 2000 CS 525 Research Project Spring 2008 Presented By - Ankur Chattopadhyay University Of Colorado At Colorado Springs

Overview  What is JPEG 2000?  Technology Description (The Overall Technique)  JPEG2000 Vs JPEG (Analysis)  Tools Used For Testing Technology  Results From The Tests Conducted  Conclusions : Why and where should we use JPEG2K?

So what is JPEG2K?  Image compression standard for the next millennium  Uses DWT (Discrete Wavelet Transform) instead of DCT  Intended to compliment, not replace, the current JPEG standards  Addresses areas where JPEG (or previous compression techniques) have failed to give best quality performance

JPEG2K  Compression technique includes modern day features: - Improved low bit-rate compression performance - Both lossless and lossy compression - Transmission in noisy environments including robustness to bit-errors - Progressive transmission by pixel accuracy and content-based resolution (Wavelet Compression Characteristics)

Main Criteria  Progressive recovery of an image by resolution or fidelity  Region Of Interest (ROI) coding (i.e. specific regions can have different resolution)  Random access to any region without fully decoding image stream  File format allows opacity information and image sequences (animation)  Good error resilience

Standard Codec Process

JPEG2K Codec Components  Source Image Model: RGB, Grayscale ‘Sheets’ (Varying size; maximum no. 2^14)  Reference Grid: Square Samples; Maximum Dimension 2^32 -1  Tiling: Divide each ‘sheet’ component into 9 smaller rectangles  Codec Structure : - Intercomponent Transform: Irreversible Component Transform (ICT) – real lossy, Reversible Color Transform (RCT) – integer lossy / lossless -Intracomponent Transform: 1D DWT (2 sub bands); 2D DWT (4 sub bands); variable component resolution R

Intra Component Transform Subbands

JPEG2K Codec Components  Quantization/Dequantization: same as JPEG  Tier-1 Coding: Bit-Plane Coding (coefficients sent into code-blocks and then packaged into “planes” with symbols)  Tier-2 Coding: Code blocks are placed into ‘data-packets’; bit-errors can occur but at individual packet level  ROI Encoding: Focus on area of priority  Code Stream: Packetized data in integer byte size  File Format: Allows opacity, ownership, origin, even animation

Why not JPEG? Shortcomings of JPEG:-  Lossy by nature  Based on DCT blocks (fixed length size)  Correlation across the block boundaries lead to noticeable and annoying ‘blocking artifacts' particularly at low bit rates  No provision/support for:- -Multi resolution -Content based progressive transmission -Robust error handling -Variable length components

Why JPEG2K? Wavelet based scheme (DWT) outperforms DCT & other coding schemes:-  Basic components have variable length  Flexible sub-band structures  At higher compression successfully avoids ‘blocking artifacts’  More robust under transmission and decoding errors  Facilitates progressive transmission of images  Better matched to the HVS characteristics because of inherent multi resolution nature  Suitable for applications where scalability and tolerable degradation are critical

Analyzing JPEG2K  For “massive compressions”, it wins hands down  Provides uniformity  Accommodates both lossy and lossless modes  ROI encoding feature  Scaled image reconstruction (progressive display)  Images can appear out-of-focus and less detailed after being compressed as the wavelet transform uniformly compresses the entire image (as opposed to DCT block encoding in JPEG) Strengths of JPEG2000Weaknesses of JPEG2000

What Are Blocking Artifacts At High Compression?

LuraWave SmartCompress Tool  Software product by LuraTech; Free download (demo version) at in different forms of packages  Successfully implements JPEG 2000 wavelet compression  Advantages: - Fast compression and decompression -Program can be run from the command line or from other programs enabling the program to act as a viewer for custom application -LuraWave.jp2 images are full fledged JPEG2000 images -Standard and can be viewed with any JPEG2000 compliant software -Both lossy & lossless compression at a selectable, user- defined compression rate, image (file) size or visual quality -Supported Image Formats: TIFF, BMP, PPM, PGM,JPEG,.JP2 and LWF (LuraWaveFormat) -Browser plug-ins: MS compatible, Netscape and ActiveX available; also PhotoShop, QuickTime, etc.

JPEG 2000 Test Tool  Memory optimized compression (Baseline)  Compression/Decompression supporting user-specified regions of higher quality within the image (ROI)  Integrated with image password protection  Another suggested tool: CompressIt by WaveL Software

Test Results Original: JPEG 157 KB Lossless: 815 KB Conversion of JPEG to Lossless.JP2 takes up more memory.

.jp K JPEG 13.7 K Recall: original file was 157 KB JPEG image 1:168 LOSSY COMPRESSION

Lossless Compression: Original:1.19 MB.jp2:665 KB On average, lossless compression is in the order of 1:2

Summary – JPEG2K Vs JPEG J2KJPEG Lossless Compression ++++ Lossy Compression Progressive Random Access ++- ROI Coding +++- Low Complexity Error Resilience ++++

Original 969 KB Bitmap.jp KB JPEG 7.29 KB JPEG2K Vs JPEG In Pics

References  ISO/IEC JTC 1/SC 29/WG 1 N 1814, “A study of JPEG 2000 still image coding versus other standards,” July 2000  ISO/IEC JTC 1/SC 29/WG 1 N 2412, “The JPEG-2000 Still Image Compression,” September 1, 2001  Richard Clark, “An introduction to JPEG 2000 and watermarking” ( )  R. Colin Johnson, “JPEG2000 wavelet compression spec approved,” December 29, 1999 ( )  (Publications & Other Material By Amara Graps)  html (Publications & Other Material By Clemens Valens)  (Publications & Other Material By Ian Kaplan)  (Publications & Other Material By Robi Polikar)