I do Fourier Transform for an image, then consider line(slice) in FFT image. When that slice isn't parallel neither x- not y-axis, coordinates are not integer. E.g. slice can hold indices {(0,0), (0.25,1), (0.5,2), (0.75,3), (1,4)...}. When using nearest-interpolation, quality of whatever I do is pure.

What techniques can you suggest to improve interpolation in Fourier grid?

  • $\begingroup$ Welcome to DSP.SE! I'm not sure what you mean by "When using nearest-interpolation, quality of whatever I do is pure." Could you rephrase it? $\endgroup$
    – Peter K.
    Sep 25, 2015 at 16:26
  • $\begingroup$ @Peter K. : I want to calculate invertible Radon transform using Projection-Slice theorem. So, when for point (0.75, 3) use value at (1,3), and then perform inverse transform, reconstruction is not perfect. $\endgroup$
    – olha
    Sep 25, 2015 at 16:33
  • $\begingroup$ Are all your coordinates multiples of 0.25 or such? $\endgroup$ Sep 26, 2015 at 7:19

1 Answer 1


The usual way to do this is to interpolate using surrounding points. There is a simple 6-point mechanism that uses:

enter image description here

This question on the Mathematics SE site has some more details. Note the answer's correction to the equation in the question.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.