I'm not quite sure of the mathematical terminology here but...
Is there a variant (or post-processing) of a Discrete Fourier Transform that separates the shape of a signal from any phase shift applied to the whole signal?
For example this image:
and this one:
should differ in at most 2 coefficients (one for each dimension in which it is shifted) in the frequency domain.
Alternatively is there a way to index images so that any image can be found in a database given a translated copy as a key?
Notes
- My images are all 1D or 2D with power-of-two sizes (but not necessarily square.)
- This project has nothing to do with OCR (even though I used a character glyph in the example.) Please do not suggest OCR-specific algorithms/libraries!
atan2(re, im)
), then performing phase unwrapping. See e.g. ljmu.ac.uk/GERI/90202.htm and ccrma.stanford.edu/~jos/fp/Phase_Unwrapping.html $\endgroup$ – Paul R Jul 12 '11 at 5:52