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.

[Jerry Guern]

Did you ever find any useful info on this? I need to do a 3D nufft, and I've found lots of good freeware in every language but matlab. The only response I see on this question is a bot response linking general information about Fourier Transforms. If you found any non-worthless info on this online, please post a link! Thanks!

[Steven Lord]

MATLAB has had nufft and nufftn functions since release R2020a. If there is some information on those documentation pages that you find unclear, or some information you were expecting to find on those pages that was not present, please ask about that information in a comment.

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-