FieldTrip

Note that this reference documentation is identical to the help that is displayed in Matlab when you type “help ft_artifact_zvalue”.

  FT_ARTIFACT_ZVALUE reads the interesting segments of data from file and
  identifies artifacts by means of thresholding the z-transformed value
  of the preprocessed raw data. Depending on the preprocessing options,
  this method will be sensitive to EOG, muscle or jump artifacts.
  This procedure only works on continuously recorded data.
 
  Use as
    [cfg, artifact] = ft_artifact_zvalue(cfg)
  or
    [cfg, artifact] = ft_artifact_zvalue(cfg, data)
 
  The output argument "artifact" is a Nx2 matrix comparable to the
  "trl" matrix of FT_DEFINETRIAL. The first column of which specifying the
  beginsamples of an artifact period, the second column contains the
  endsamples of the artifactperiods.
 
  If you are calling FT_ARTIFACT_ZVALUE with only the configuration as first
  input argument and the data still has to be read from file, you should
  specify
    cfg.headerfile
    cfg.datafile
  and optionally
    cfg.headerformat
    cfg.dataformat
 
  If you are calling FT_ARTIFACT_ZVALUE with also the second input argument
  "data", then that should contain data that was already read from file
  a call to FT_PREPROCESSING.
 
  If you encounter difficulties with memory usage, you can use
    cfg.memory = 'low' or 'high', whether to be memory or computationally efficient, respectively (default = 'high')
 
  The required configuration settings are:
    cfg.trl
    cfg.continuous
    cfg.artfctdef.zvalue.channel
    cfg.artfctdef.zvalue.cutoff
    cfg.artfctdef.zvalue.trlpadding
    cfg.artfctdef.zvalue.fltpadding
    cfg.artfctdef.zvalue.artpadding
 
  If you specify
    cfg.artfctdef.zvalue.interactive = 'yes', a GUI will be started and you
      can manually accept/reject detected artifacts, and/or change the threshold
 
  If you specify
    cfg.artfctdef.zvalue.artfctpeak='yes', the maximum value of the artifact 
        within its range will be found; saved into cfg.artfctdef.zvalue.peaks
  Use also, e.g. as input to DSS option of ft_componentanalysis:
    cfg.artfctdef.zvalue.artfctpeakrange= [-0.25 0.25]; (in seconds), (for example) 
        to indicate range around peak to include, saved into cfg.artfctdef.zvalue.dssartifact
        Default values: [0 0]
        Range will respect trial boundaries (i.e. be shorter if peak is near beginning or end of trial)
        Samples between trials will be removed; thus this won't match .sampleinfo of the data structure
 
  Configuration settings related to the preprocessing of the data are
    cfg.artfctdef.zvalue.lpfilter      = 'no' or 'yes'  lowpass filter
    cfg.artfctdef.zvalue.hpfilter      = 'no' or 'yes'  highpass filter
    cfg.artfctdef.zvalue.bpfilter      = 'no' or 'yes'  bandpass filter
    cfg.artfctdef.zvalue.lnfilter      = 'no' or 'yes'  line noise removal using notch filter
    cfg.artfctdef.zvalue.dftfilter     = 'no' or 'yes'  line noise removal using discrete fourier transform
    cfg.artfctdef.zvalue.medianfilter  = 'no' or 'yes'  jump preserving median filter
    cfg.artfctdef.zvalue.lpfreq        = lowpass  frequency in Hz
    cfg.artfctdef.zvalue.hpfreq        = highpass frequency in Hz
    cfg.artfctdef.zvalue.bpfreq        = bandpass frequency range, specified as [low high] in Hz
    cfg.artfctdef.zvalue.lnfreq        = line noise frequency in Hz, default 50Hz
    cfg.artfctdef.zvalue.lpfiltord     = lowpass  filter order
    cfg.artfctdef.zvalue.hpfiltord     = highpass filter order
    cfg.artfctdef.zvalue.bpfiltord     = bandpass filter order
    cfg.artfctdef.zvalue.lnfiltord     = line noise notch filter order
    cfg.artfctdef.zvalue.medianfiltord = length of median filter
    cfg.artfctdef.zvalue.lpfilttype    = digital filter type, 'but' (default) or 'fir'
    cfg.artfctdef.zvalue.hpfilttype    = digital filter type, 'but' (default) or 'fir'
    cfg.artfctdef.zvalue.bpfilttype    = digital filter type, 'but' (default) or 'fir'
    cfg.artfctdef.zvalue.detrend       = 'no' or 'yes'
    cfg.artfctdef.zvalue.demean        = 'no' or 'yes'
    cfg.artfctdef.zvalue.baselinewindow = [begin end] in seconds, the default is the complete trial
    cfg.artfctdef.zvalue.hilbert       = 'no' or 'yes'
    cfg.artfctdef.zvalue.rectify       = 'no' or 'yes'
 
  See also FT_REJECTARTIFACT, FT_ARTIFACT_CLIP, FT_ARTIFACT_ECG, FT_ARTIFACT_EOG,
  FT_ARTIFACT_JUMP, FT_ARTIFACT_MUSCLE, FT_ARTIFACT_THRESHOLD, FT_ARTIFACT_ZVALUE