Hi Jinglei,
If the pipeline has not been developed yet, do you recommend the Unringing and Bias field correction following the minimal preprocessing pipeline from HCP?
Unringing should absolutely not be done on minimally processed data. As soon as any sort of image interpolation step is performed (as occurs for e.g. motion / eddy current / susceptibility field correction), the mathematical theory behind the manifestation of the effect and its estimation and correction no longer applies.
Bias field correction can be done on minimally processed data using either method, and generally mtnormalise is recommended over dwibiascorrect. mtnormalise can’t do quite as good a job on HCP data as it can on conventional data because of the gradient non-linearity effects present in the data, but it will actually try to somewhat correct for these.
Rob