[Pkg-exppsy-pynifti] PyNIfTI/nifticlib/zlib bug on win32 [SCREENSHOT]

[Michael Hanke]

here is the screenshot -- thanks Per!


On Thu, Apr 02, 2009 at 02:55:00PM +0200, Michael Hanke wrote:
> Hi all,
> 
> [cross-posting to pymvpa list too, since there are probably most users]
> 
> we have a bug!
> 
> It looks like PyNIfTI is not working properly on win32 (and maybe on
> MacOS too). The bug shows up when writing an image to a _compressed_ NIfTI
> file. I am attaching a screenshot that shows an axial view of an image
> that is shipped as part of the PyMVPA sources ('example4d.nii.gz'). The
> grayscale image is the original and the reddish one is the resulting
> image of the following operation:
> 
>  1. Open the compressed image with pynifti (on win32).
>  2. Write it again to a compressed file (on win32).
> 
> The bug does not show up when 2.) writes to an _uncompressed_ image --
> which somewhat indicates a zlib issue (I guess most people are using
> zlib 1.2.3 now).
> 
> As PyNIfTI is not statically linked to zlib you can replace the library
> with an unaffected one. There were reportes that zlib 1.2.2 is not
> affected, but so far I cannot confirm that.
> 
> In my opinion this bug is a little too specific to be a general zlib
> issue -- very unlikely that such a widely used library shows such a
> gross bug. More likely is a bug in the handling of compressed files in
> the nifticlib.
> 
> However, it needs more work and time to track this bug down. In the
> meantime I'd recommend to test whether your installation is affected and
> revert to uncompressed images in that case.
> 
> It would be helpful if you could report to the pynifti mailinglist
> (pkg-exppsy-pynifti at lists.alioth.debian.org) if you hit this bug and
> tell us what system you are using (zlib version, nifticlib version (if
> you are not using the one built into pynifti), and finally pynifti
> version).
> 
> On the Debian systems I have tested so far I cannot reproduce this bug,
> but I see it on a Win 2003 Server with the lastest pynifti and zlib
> 1.2.3.
> 
> 
> Michael
> 
> -- 
> GPG key:  1024D/3144BE0F Michael Hanke
> http://apsy.gse.uni-magdeburg.de/hanke
> ICQ: 48230050

-- 
GPG key:  1024D/3144BE0F Michael Hanke
http://apsy.gse.uni-magdeburg.de/hanke
ICQ: 48230050
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