If the common area of two images is determined after the first pass, perform the second pass on the truncated images containing that common area. The results could be somewhat better and it could be quite fast since the images would be smaller.
Resampling for sub-pixel resolution could also be an option here.
If the common area of two images is determined after the first pass, perform the second pass on the truncated images containing that common area. The results could be somewhat better and it could be quite fast since the images would be smaller. Resampling for sub-pixel resolution could also be an option here.