[Insight-developers] Nrrd format changes

[Karthik Krishnan]

Yes, it was there in 1 release - 2.4 and changed into release 2.6.
(Maybe I am wrong.) . Do you need me to patch any releases ? Or add some
information into the Wiki to save somebody possible pain ? 

Aside from the file format changes and related pain, I think its a good
thing cause the previous way of iterating through volumes could have
been rather slow.

Nrrd's rather convenient to represent DWI volumes. Its got tags to
represent DWI gradients as key value tags, store multiple gradients and
the B0 in one file. It can also store masked Diffusion Tensor volumes
and has some functionality to account for cases where the tensor
measurement frame may be different.  

Of course Gordon knows better.

Thanks
karthik


On Tue, 2006-01-10 at 14:36 -0500, Lorensen, William E (GE, Research)
wrote:
> Was the old header format in an ITK release? If so, is there a way to support the old and new versions? We must be considerate of our user base...
> 
> Bill
> 
> -----Original Message-----
> From: insight-developers-bounces+lorensen=crd.ge.com at itk.org
> [mailto:insight-developers-bounces+lorensen=crd.ge.com at itk.org]On Behalf
> Of Karthik Krishnan
> Sent: Tuesday, January 10, 2006 1:22 PM
> To: Gordon Kindlmann
> Cc: Insight-developers (E-mail)
> Subject: [Insight-developers] Nrrd format changes
> 
> 
> Hi Gordon,
> 
> I have some old DWI headers for Nrrd. There were some nrrd format
> changes, probably for more efficient iteration in terms of reading each
> gradient image etc.. Do you have a quick and dirty program that does
> this re-ordering ? I presume you've had the need to do this yourself. If
> you don't that's ok, its an easy thing thing to do.
> 
> Could you please tell me what the new header is supposed to look like ?
> Here is the old header.
> 
> ----------------------
> NRRD0004
> content: dwi
> type: short
> dimension: 4
> space: right-anterior-superior
> sizes: 256 256 50 31
> thicknesses:  NaN  NaN 4  NaN
> space directions: (0.9375,0,0) (0,0.9375,0) (0,0,2.5) none
> centerings: cell cell cell none
> kinds: space space space list
> endian: little
> encoding: raw
> space units: "mm" "mm" "mm"
> space origin: (0, 0, 0)
> data file: xt_dwi.img
> modality:=DW
> DW_gradient_001:=-1.000000 	 0.000000 	 0.000000
> DW_gradient_002:=-0.166000 	 0.986000 	 0.000000
> DW_gradient_003:=0.110000 	 0.664000 	 0.740000
> DW_gradient_004:=-0.901000 	 -0.419000 	 -0.110000
> DW_gradient_005:=0.169000 	 -0.601000 	 0.781000
> DW_gradient_006:=0.815000 	 -0.386000 	 0.433000
> DW_gradient_007:=-0.656000 	 0.366000 	 0.660000
> DW_gradient_008:=-0.582000 	 0.800000 	 0.143000
> DW_gradient_009:=-0.900000 	 0.259000 	 0.350000
> DW_gradient_010:=-0.693000 	 -0.698000 	 0.178000
> DW_gradient_011:=-0.357000 	 -0.924000 	 -0.140000
> DW_gradient_012:=-0.543000 	 -0.488000 	 -0.683000
> DW_gradient_013:=0.525000 	 -0.396000 	 0.753000
> DW_gradient_014:=0.639000 	 0.689000 	 0.341000
> DW_gradient_015:=0.330000 	 -0.013000 	 -0.944000
> DW_gradient_016:=0.524000 	 -0.783000 	 0.335000
> DW_gradient_017:=-0.609000 	 -0.065000 	 -0.791000
> DW_gradient_018:=-0.220000 	 -0.233000 	 -0.947000
> DW_gradient_019:=0.004000 	 -0.910000 	 -0.415000
> DW_gradient_020:=0.511000 	 0.627000 	 -0.589000
> DW_gradient_021:=-0.414000 	 0.737000 	 0.535000
> DW_gradient_022:=0.679000 	 0.139000 	 -0.721000
> DW_gradient_023:=-0.884000 	 -0.296000 	 0.362000
> DW_gradient_024:=-0.262000 	 0.432000 	 0.863000
> DW_gradient_025:=-0.088000 	 0.185000 	 -0.979000
> DW_gradient_026:=-0.294000 	 -0.907000 	 0.302000
> DW_gradient_027:=-0.887000 	 -0.089000 	 -0.453000
> DW_gradient_028:=-0.257000 	 -0.443000 	 0.859000
> DW_gradient_029:=-0.086000 	 0.867000 	 -0.491000
> DW_gradient_030:=-0.863000 	 0.504000 	 -0.025000
> -----------------------------------
> 
> I presume the image dwi.img should be re-ordered so that 
> sizes: 31 256 256 50
> instead of 
> sizes: 256 256 50 31
> 
> so that the gradients vary the fastest.
> 
> Is that the only change ?
> 
> Thanks 
> karthik
> 
> 
> 
> 
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