Start out with a signal 256 pixels long and interpolate this directly using the Fourier transform into a signal which has 1024 points

Start out with a signal 256 pixels long and interpolate this directly using the Fourier transform into a signal which has 1024 points. I'm fairly new to MATLAB but I understand this is using interpft(x,n) and I tried using the example given on the website but I keep getting a weird result. Can anyone tell me what I'm missing/doing wrong? Thank you!!

Answer 1

[J. Webster]

Not exactly sure what you're doing. But I think you should look up something called Nyquist Upsampling.

The method is you take the fourier transform of your data, then zero-pad the transform so that it has as many samples as you need (1024). Then do an inverse transform. The result will have 1024 numbers in the array. This, I think, is faster and cleaner than using interpolation.

Remember that the transform output will have positive frequencies first, then negative frequencies reversed, so be careful where you put the zeros.