Need help with using nufftn for images. The arguments and output format are unclear in the documentation.

For one of my projects I need Fourier transform values at non-integer frequencies of images. Zero padding doesn't help for my application. I'm trying to use nufftn without specifying sample points i.e., nufft(X, [], f). But I couldn't quite understand the output. Documentation is not elaborate enough. I really appreciate if anyone can help me with this. Thanks in Advance.

Answer 1

[Yash]

Hi Saivivek,

The MATLAB function "nufftn" returns the N-D discrete fast Fourier transform of N-D array "X" at sample points "t" and query points "f". The return value is of type complex. In order to interpret the output and get an intuitive visual understanding of the same, refer to the following resources:

• https://math.stackexchange.com/questions/414365/how-to-interpret-fourier-transform-result
• https://math.stackexchange.com/questions/1586683/whats-exactly-the-output-of-fourier-transform
• https://www.youtube.com/watch?v=spUNpyF58BY
• Videos number 7,8 and 9 in this playlist: https://www.youtube.com/playlist?list=PLhPfNw4V4_YRUuWnrtClovPKxU_gJOXH-