Storing floating point values

[devDonnn]

Hi,

I have a NIfTI image volume which values range from -1 to 2. When I convert to DICOM I get a binary image where only the values above 1 are kept. Thus, all the negative and values less than 1 are cropped to be 0. Why is that? How can I store negative values as well?

EDIT: that actually seems to be a problem of not being able to store floating point values, the image is saved as UNSIGNED INT. How can I store floating point values? The rescale option (-r) does not do the job.