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Bug 1095 - negative trialpadding in ft_artifact_zvalue

Reported 2011-11-01 12:02:00 +0100
Modified 2019-08-10 11:56:51 +0200
Product: FieldTrip
Component: core
Version: unspecified
Hardware: All
Operating System: All
Importance: P4 enhancement
Assigned to: Stephen Whitmarsh
Depends on:
See also:

Stephen Whitmarsh - 2011-11-01 12:02:18 +0100

ft_artifact_zvalue has the possiblity for specifying trialpadding. This helps prevent edgeartifacts (of the z-value based on edges, especially when using filter options), but only when reading from disc. When you have data in memory already, after preprocessing, this does not work. Solution might be simple: provide possiblity for 'negative trialpadding', i.e. only do artifact rejection on smaller window (e.g. starting 100 ms later, and ending 100 ms earlier). What do you think? (p.s. ofcourse working with partial artifact rejection is a possible workaround, but only in some cases). cheers, Stephen

Boris Reuderink - 2011-11-17 10:46:50 +0100

Changed the status of bugs without a specific owner to UNCONFIRMED. I'll try to replicate these bugs (potentially involving the submitter), and change confirmed bugs to NEW. Boris

Boris Reuderink - 2011-11-17 14:10:47 +0100

What should we do? Discuss in meeting? On mailing list? Here?

Boris Reuderink - 2011-11-28 16:07:37 +0100


Boris Reuderink - 2012-01-03 14:32:04 +0100


Stephen Whitmarsh - 2012-02-13 18:14:18 +0100

I now tried to fix the problem with a workaround that ended up driving into another dead end bug (will post in another) Taking another look at this suggestion for improvement I think the best way would actually be to introduce a toi field. That should also we relatively easy for someone who knows the code of ft_artifact_zvalue - which seems it could use a little cleaning up anyhow. Anyone wants me to look over their shoulder, or to buy them chocolates? And yes that is a bribe :-) ~S~

Jan-Mathijs Schoffelen - 2012-02-13 19:30:39 +0100

I strongly oppose against 'cleaning up' ft_artifact_zvalue' because it has been reimplemented about five times by now (most of the times by me), and I am pretty happy with the result... I don't understand what is meant with the 'toi'. If it is the purpose to disregard 'artifacts' close to the edge of the trial (with data in memory), actual specifying a negatively valued trlpadding makes sense, and could be implemented without too much hassle. Of course the default would still remain 0.

Jan-Mathijs Schoffelen - 2012-02-23 12:11:47 +0100

FIXME: we should also think about the correct begin and endpoints of the detected artifacts in the context of negative trial-padding. When artpadding > 0 the begin/end points could fall within the padded part of the data. This is not the case at present

Stephen Whitmarsh - 2012-05-31 10:23:37 +0200

this wsa done a while ago. note its use is documented on the wiki

Robert Oostenveld - 2019-08-10 11:56:51 +0200

This closes a whole series of bugs that have been resolved (either FIXED/WONTFIX/INVALID) for quite some time. If you disagree, please file a new issue describing the issue on