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

  FT_REJECTCOMPONENT backprojects an ICA (or similar) decomposition to the
  channel level after removing the independent components that contain
  the artifacts. This function does not automatically detect the artifact
  components, you will have to do that yourself.
  Use as
     [data] = ft_rejectcomponent(cfg, comp)
  or as
     [data] = ft_rejectcomponent(cfg, comp, data)
  where the input comp is the result of FT_COMPONENTANALYSIS. The output
  data will have the same format as the output of FT_PREPROCESSING.
  An optional input argument data can be provided. In that case
  componentanalysis will do a subspace projection of the input data
  onto the space which is spanned by the topographies in the unmixing
  matrix in comp, after removal of the artifact components.  Please use
  this option of including data as input, if you wish to use the output
  data.grad in further computation, for example for leadfield computation.
  The configuration structure can contain
    cfg.component  = list of components to remove, e.g. [1 4 7] or see FT_CHANNELSELECTION
    cfg.demean     = 'no' or 'yes', whether to demean the input data (default = 'yes')
    cfg.updatesens = 'no' or 'yes' (default = 'yes')
  To facilitate data-handling and distributed computing you can use
    cfg.inputfile   =  ...
    cfg.outputfile  =  ...
  If you specify one of these (or both) the input data will be read from a *.mat
  file on disk and/or the output data will be written to a *.mat file. These mat
  files should contain only a single variable, corresponding with the
  input/output structure.