[MINC-development] MINC2 file with floating-point voxels and slice normalization

[Andrew Janke]

Hi Vladimir,

On 18 January 2013 06:36, Vladimir S. FONOV <vladimir.fonov at gmail.com> wrote:
> I came across a following problem -  I have got a minc volume with float
> type, but with image_max and image_min specifying range for each slice.
>
> It turns out that there is actually no normalization performed in the actual
> voxel values (as one would expect) and MINC1 api while dealing with this
> file forks properly.
>
> Unfortunately, MINC2 api checks if the image_max and image_min variables
> have dimension more then 1 and if it is the case, the inter-slice
> normalization is enabled  (i.e see
> https://github.com/BIC-MNI/libminc/blob/master/libsrc2/volume.c#L1122 ).

Ack! good catch.

> So, the question to MINC founding fathers - should MINC2 api be modified to
> make sure that no inter-slice normalization happens when voxel type is
> float, or is there any some other considerations?

My understanding was that float/double MINC files don't do slice
normalisation as it doesn't make sense. Float+Double filetypes specify
a precision for your datatype, the range is irrelevant. So yes this
should be removed. It was my understanding that if you convert a file
to float/double using MINC tools the slice max/mins are discarded.

I have taken the liberty of CC'ing Peter on this just to make sure,
trust it isn't too much of an intrusion 10 years or so down the
track...



a