You know about Jpeg2000 right? Wavelet compression, top notch work of the 90’s, an image compression format that promises better results than JPEG and can be lossless for some pixel types. Well it totally exists and commercial software uses it quite a bit. It has taken quite a hold of the satellite imaging sector as it allows image compression to 1/6th the size of a traditional TIFF. Unfortunately there doesn’t seem to be any good open source libraries available for everyone else. There’s Jasper, OpenJPEG, and CQJ2K but they were always a magnitude or more slower than the commercial product Kakadu.
OpenJPEG had an official 2.0.0 release on December 1st of last year and it is actually worth a glance. Unfortunately the current release of GDAL, version 1.9.2, doesn’t support this new release. It was designed for a prototype of OpenJPEG found at revision 2230 of OpenJPEG’s SVN repo. If you are willing though, the new OpenJPEG v2 release contains the executables opj_decompress and opj_compress for conversion of JP2 files to and from TIFF, PNG, and JPEG formats. Another alternative is also downloading the current development version of GDAL 1.10 which has support for the new OpenJPEG v2 library and can leverage it to read things like NTF. I performed some rough / unscientific tests of these configurations this weekend and my notes are below. My conclusion is that OpenJPEG 2.0.0 is decently nice and I can’t wait for the next release of GDAL so that I can roll it into Ames Stereo Pipeline.
|OJP r2230's j2k_to_image||greater than 2 days||~1 MB|
|GDAL 1.9.2's gdal_translate w/ OJP r2230||greater than 2 days||~10 MB|
|OJP v2's opj_decompress||4 min||~2 GB|
|GDAL 1.10's gdal_translate w/ OJP v2 w/ GDAL_CACHEMAX=512||5 min||~600 MB|