Synchronous temporal filter workflow

[rciric]

I have a workflow that applies the same temporal filtering procedure to both 4D NIfTI time series and 2D TSV time series (e.g., confounds). This is necessary to avoid frequency mismatch issues that can potentially reintroduce nuisance signals at particular frequencies during the regression/fit step.

I would like to make this workflow available, but I'm not sure what the best place for this is (niworkflows vs. niflows vs. fmriprep). In brief:

• This would be a dependency of the Power denoising workflow that I was hoping to integrate into fmriprep down the line.
• The workflow could also potentially be a standalone for synchronous filtering of fmriprep outputs before feeding them into fitlins.
• If we build a separate confound regression/denoising/qcfc module, this would also be an explicit dependency for that.
• For users who are are all right using an ideal filter/cosine basis, this workflow is generally unnecessary. I haven't really investigated the merits of the different filtering approaches, but both the cosine basis method (simultaneous filtering) and the parallel generalised filtering method implemented in this workflow should in theory get around the frequency mismatch/nuisance reintroduction problem.