[Insight-developers] Nrrd format changes

[Karthik Krishnan]

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