Can two 2D images be registered

I used reg-aradin - ref img1. tif - flo img2. tif, which prompted me that the Nifti library is used by default. But two-dimensional images are generally in TIF and PNG formats.
So I have a few questions:
Can 2D-2D registration be performed?
How to perform 2D-2D registration? Which executable file should be used (reg_cladin，reg_f3d，reg_resample，reg_transform，reg_jacobian，reg_average，reg_tools）？