Depends on what you mean by floating point coordinates.

NumPy arrays exclusively support integer indexing. But obviously, a lot of images (flat field work with maps, scale drawings, blueprints, and medical images) have a parallel real-world coordinate system associated with each dimension. To handle these cases, you need a conversion between image coordinate system and world coordinates.

I think here the question is more - could this algorithm pin down a feature at a higher resolution than the image grid? A lot of techniques can do this, and if they can, you need at least the ability to output floats.