If you have any experience in surfing the Internet, you no doubt cringe when you start loading an image intensive web site. I can say that, because of my 56k analogue connection, there are certain sites I avoid, sites that force me to download several hundred images before I can even read a single line of text. It is for this reason, as well as others to be revealed, that I personally hope the JPEG 2000 standard achieves its potential.
JPEG is an acronym for Joint Photographic Experts Group. JPEG is a group of several hundred individuals who work with the International Standards Organization, or ISO. A portion of JPEG are working on the JPEG 2000 standard, a standard that is in the final stages of ISO approval and will soon be known to the world as ISO 15444.
The study of wavelets, particularly wavelet transformations, led JPEG to the new standard. The old jpeg's that we are familiar with compress an image with the use of Fourier transforms. These Fourier transforms do an alright job, and, when jpeg's were first implemented, this was the best anyone could do. However, with the introduction of wavelets, the folks at JPEG quickly realized that image compression could be done much better with wavelet transformations.
JPEG 2000 allows for a 200:1 compression ratio with very little appreciable degradation in image quality. It has a lossy and lossless version of image compression. It will allow for third-party, royalty-bases extensions to the compression standard. It can differentiate between text and images in a single file and switch compression schemes, on the fly, bases on that distinction. As an extension to that property, it can also identify "Regions of Interest", or ROI's, and use different compression schemes to help preserve the image quality of those regions. All of these properties may sound quite impressive, but it's not until one sees the new standard in action that one truly becomes impressed. Please study this image.
In Part 1 of the document Jpeg2000 : Image Compression Fundamentals, Standards, and Practice, "JPEG 2000 Image Coding System," details the core of the JPEG 2000 process. I will touch on nearly all of the stages of the JPEG 2000 image compression process. This includes Codestream Syntax, Data Ordering, Arithmetic Entropy Encoding, Coefficient Bit Modeling, Quantization, Discrete Wavelet Transformation of Tile Components, DC Level Shifting and Component Transformations, and Coding of Images with Regions of Interest. Hopefully, at the end of all of this, you will come to appreciate the JPEG 2000 standard as I have.
