Dear SPM experts,
I am writing to inquire about several questions regarding the Gauss-Newton optimization used in the head motion correction code spm_realign.m in SPM2(Although the latest version is SPM12, I focus on SPM2).
I have found that the specific values of the number of iterations and point selection intervals in the Gauss-Newton iteration algorithm can significantly affect the correction results. Could you please explain how SPM determines the number of iterations and point selection intervals?
Additionally, I would like to inquire whether SPM uses any auxiliary methods to improve accuracy aside from the Gauss-Newton iteration algorithm, such as contour extraction.
I am also eager to find out what methods or parameters SPM use to evaluate the effects of the head motion correction.
Any insights or feedback on this matter would be greatly appreciated. Thank you for your time and assistance.
Best,
Yuqi Yin
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