The JPEG2000 compression algorithm was released by an ISO standardization committee in January 2001. It is based on the existing JPEG specifications and adds three important things to the existing standard:
- It adds a wavelet-based algorithm to the existing JPEG compression algorithms. This wavelet-transformation algorithm offers improved image quality at very high compression ratios.
- JPEG2000 is said to produce as much as a 20% improvement in compression efficiency over the current JPEG format.
- It also offers an optional lossless compression mode. Lossless JPEG2000 files areabout half the size of the original.
Advantages of JPEG2000 compression
- JPEG2000 is a very efficient compression algorithm. It has mainly been developed for use on the internet.
- The addition of a lossless compression mode is interesting for prepress use.
Disadvantages of JPEG2000 compression
Even though I was a fan of the algorithm for some time, most people I know have reverted back to using regular JPEG compression for 3 reasons:
- Compatibility with legacy systems: only recent workflows or computer applications can deal with JPEG2000 compression. If you need to distribute data, this can be a real showstopper.
- JPEG2000 is a resource hog: compressing data requires lots of CPU-horsepower
- At compression ratio’s below 25:1, the wavelet-based algorithm produces less blocky but somewhat less detailed images compared to regular JPEG compression. Too much compression is never a good idea.
How to save Jpeg 2000 files in Photoshop CS3
Next to the Jpeg2000 compression algorithm, there is also an associated Jpeg2000 file format. There are actually two of them: the regular JP2 file format and an extended JPEG 2000 format which uses the .jpf extension. By default Photoshop cannot write these file formats. A plug-in to add support for them can be found on the installation CD in Goodies/Optional Plug‑Ins/File Formats. Copy the plug-in to Adobe Photoshop CS3/Plug‑Ins/File Formats.