[Insight-developers] question regarding nifti IO

[Nick Tustison]

Thank you very much.  That certainly explains things.

On Wed, Apr 29, 2009 at 9:37 AM, Hans Johnson <hans-johnson at uiowa.edu>wrote:

>  Nick,
>
> The reason is that the image dimensions are stored in “short integers”
>
> Insight/Utilities/nifti/niftilib/nifti1.h:157
>
> short dim[8];        /*!< Data array dimensions.*/  /* short dim[8];
>        */
>
> echo "2^15-1"|bc -l
> 32767
>
> Hans
>
>
>
> On 4/28/09 8:03 PM, "Nicholas Tustison" <ntustison at gmail.com> wrote:
>
> Developers,
>
> My colleague, Brian Avants, asked that I post the following question to the
> Insight Developers' list.  Essentially, as he points out below, and I've
> reproduced using my own code, it seems as though 1-D images can't be created
> in nifti format where the size exceeds ~30,000 pixels but can be created
> using the mhd format.  Is this behavior known and is there a particular
> reason for it?
>
> Thanks,
> Nick Tustison
>
> Begin forwarded message:
>
> **
>
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> From: brian avants <stnava at gmail.com
> >
> *Date: *April 28, 2009 1:48:58 PM EDT
> *To: *Nicholas Tustison <ntustison at gmail.com>
> *Subject: bug nifti writer?
> *
>
>
>
> is this a known/unknown bug?
>
> only appears to happen if #voxels exceeds about 30,000.
> suggesting datatype problem.
>
> see below:
>
> # first, just print the mhd header
>
> $ PrintHeader zero2.mhd
>  Spacing [1, 1]
>  Origin [0, 0]
>  Direction
> 1 0
> 0 1
>  Size
> [1, 65536]
>
> # convert to nifti
>  $ MultiplyImages 2 zero2.mhd 1 zero2.nii
>
> # print nifti header
> $ PrintHeader zero2.nii
>  Spacing [1, 1]
>  Origin [0, 0]
>  Direction
> 1 0
>  0 1
>
>  Size
> [1, 1]
>
> # size is wrong in terms of the header info
> # but not in terms of the raw data ...
> $ ls -l zero2.nii
> -rw-r--r--  1 user  user  262496 Apr 28 13:37 zero2.nii
>
> $ ls -l zero2.raw
> -rw-r--r--  1 user  user  262144 Mar 25  2008 zero2.raw
>
> # if i convert zero2.nii to mhd the size is wrong
> ls -l zero3.raw
> -rw-r--r--  1   user  user  4 Apr 28 13:42 zero3.raw
>
>
>
>
>
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