torchkbnufft
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data range changed after processing
For example, in the provided code example Toeplitz Example,you can find that:
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.
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.
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 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
Closing as this does not document a bug.