What formula does dcm2niix uses when producing a bvec file for a DTI scan in cases there is an angulation in the dicom files i.e., tag (0020,0037), Image Orientation (Patient), exhibit some transformation different from the identity matrix?

Does the values just read from the Dicom header, or does dcm2niix rotate the values from the dicom header according to some formula so that they will fit the oriantation that is in the nifti file?

If the last is the correct state, what formula does dcm2niix uses?

Yaron Caspi