Version and/or option to consent subjects to share undefaced data

An open repository of structural data with intact facial features could be a valuable resource. The most obvious use case is in developing defacing tools, permitting the validation of methods, quantifying the effects on downstream processing (see #53), or the automatic detection of defaced/undefaced images.

To obtain subject consent and ethics committee approval, I can see two paths:

1) A specific version of the OBC in which subjects consent to share undefaced data.
2) An addition to the standard OBC which allows subjects to opt-in to this additional release.

The former would allow studies to be planned entirely around releasing undefaced datasets. The latter would allow for an accumulation of some subjects over many studies.

One point to note in any disclosure is that it's more-or-less irrevocable. Since brains are like fingerprints, a defaced subject in one study can be associated with an undefaced subject in another study, and a subject would effectively be consenting to release all past and future contributions to open datasets.

How do people feel about this?

Start by reading the existing Open Brain Consent materials and the discussion in issue #58. Determine whether the project should support a separate consent version or an opt-in addition, and document the approved consent and disclosure requirements when the scope is agreed.

Written by the indexing model from the issue text.