[Neuroimaging] Nibabel API change - always read as float
moloney at ohsu.edu
Tue Jul 7 20:16:15 CEST 2015
> the nifti-1 standard (http://nifti.nimh.nih.gov/pub/dist/src/niftilib/nifti1.h)
> has a datatype field. there are two scenarios with scaling:
> 1. scl_slope == 0:
> 2. scl_slope != 0:
> data should be converted to IEEE-754 floats as per the nifti standard.
> given nifti was around 2001 this probably did not reflect the updated
> IEE754-2008 standard, but > relied on the 1985 standard. i don't think the
> nifti-1 standard makes it clear what this float should correspond to, i.e.,
> 16/32/64/128 bit floats.
I don't see that in the standard. All I see is:
If the scl_slope field is nonzero, then each voxel value in the dataset
should be scaled as
y = scl_slope * x + scl_inter
where x = voxel value stored
y = "true" voxel value
Normally, we would expect this scaling to be used to store "true" floating
values in a smaller integer datatype, but that is not required. That is,
it is legal to use scaling even if the datatype is a float type (crazy,
perhaps, but legal).
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the Neuroimaging