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data range changed after processing

Open bigponglee opened this issue 2 years ago • 3 comments

For example, in the provided code example Toeplitz Example,you can find that: image After applying the nufft operation, the range of the data has changed a lot. Although it is possible to force the unification of the data range through data normalization, how to normalize itself is still debatable.

bigponglee avatar Aug 20 '22 07:08 bigponglee

Hello @bigponglee, this is entirely expected. By using the NUFFT you are applying a coordinate transformation to an integral without using the Jacobian to normalize the new unit of integration. There are methods such as density compensation to partially, but not completely compensate for the effect.

mmuckley avatar Aug 25 '22 20:08 mmuckley

Hi @mmuckley, thanks for the explanation! I'm also encountering this problem and using an ugly operator normalization to imperfectly fix it. Would you share some papers you mentioned as density compensation? It would be very helpful! Many thanks! Best, Wenqi

wenqihuang avatar Sep 05 '22 09:09 wenqihuang

@wenqihuang several people use this paper as a reference: https://onlinelibrary.wiley.com/doi/abs/10.1002/(SICI)1522-2594(199901)41:1%3C179::AID-MRM25%3E3.0.CO;2-V

mmuckley avatar Sep 22 '22 14:09 mmuckley

Closing as this does not document a bug.

mmuckley avatar Oct 25 '22 13:10 mmuckley