James Holton schrieb: ...
In any case, I think it is important to remember that there are good reasons for leaving image file formats uncompressed. Probably the most important is the activation barrier to new authors writing new programs that read them. "fread()" is one thing, but finding the third-party code for a particular compression algorithm, navigating a CVS repository and linking to a library are quite another! This is actually quite a leap for those of us who never had any formal training in computer science. Personally, I still haven't figured out how to read pck images, as it is much easier to write "jiffy" programs for uncompressed
pck code can be found at http://www.ccp4.ac.uk/dist/lib/src/pack_c.c CBF code is at http://www.bernstein-plus-sons.com/software/CBF/ Both are under GPL
data. For example, if all you want to do is extract a group of pixels (such as a spot), then you have to decompress the whole image! In computer speak: fseek() is rendered useless by compression. This could be why Mar opted not to use the pck compression for their newer CCD-based detectors?
thinking about the many GB written daily at a synchrotron beamline, I wish they had !
That said, compressed file systems do appear particularly attractive if space is limiting. Apparently HFS can do it, but what about other operating systems? Does anyone have experience with a Linux file system that both supports compression and doesn't get corrupted easily?
One possibility in Linux is ZFS over FUSE; this has a large number of advantages over other filesystems (except Btrfs) - see http://www.linux-magazine.com/w3/issue/103/ZFS.pdf . The article explains installation for Ubuntu. I must admit that I did not try it so far.
The alternative would be Btrfs, see http://www.h-online.com/open/The-Btrfs-file-system--/features/113738 . This is available for latest Fedora and Ubuntu, is part of the recently released 2.6.31 kernel (http://www.h-online.com/open/Kernel-Log-2-6-31-Tracking--/features/113671), and will therefore in the future be available in all distros.
best, Kay -- Kay Diederichs http://strucbio.biologie.uni-konstanz.de email: kay.diederi...@uni-konstanz.de Tel +49 7531 88 4049 Fax 3183 Fachbereich Biologie, Universitaet Konstanz, Box M647, D-78457 Konstanz
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