Perform simple denoising before estimating CompCor

[chrisgorgo]

CompCor can pick on trivial noise patterns that would be removed through other means. To avoid this and let CompCor focus on the non-trivial noise the following simple denoising steps should be performed prior to signal extraction:

• Regressing out non-steady state outliers (see Add steady state detector #360)
• High-pass filter with 0.008 Hz (remove signals with slower frequencies than 0.008 Hz)

[chrisgorgo]

High pass filtering could be implemented in the same regression step via Discrete Cosine Transform basis set (which could also be included in the confounds).

Source: https://books.google.com/books?id=AoWD2S8759kC&pg=PA756&lpg=PA756&dq=highpass+DCT+basis+functions+filter&source=bl&ots=EWAvbB8X26&sig=YbOnaVf4Bq8nWNB9v6UK03SjjeY&hl=en&sa=X&ved=0ahUKEwjb4u_B95XSAhUH-mMKHQudCLgQ6AEIRDAJ#v=onepage&q=highpass%20DCT%20basis%20functions%20filter&f=true

[chrisgorgo]

There should be so code for this in nistats https://github.com/nistats/nistats

[chrisgorgo]

Is non steady state also included in denoising?

[effigies]

Nope.