  Slitless (or wide field) imaging spectroscopy provides simultaneous imaging
and spectral information from a wide field of view, which allows for rapid
spectroscopic data collection of extended sources. Depending on the size of the
extended source combined with the spatial resolution and spectral dispersion of
the instrument, there may be locations in the focal plane where spectral lines
from different spatial locations overlap on the detector. An unfolding method
has been successfully developed and demonstrated on the recent rocket flight of
the Marshall Grazing Incidence X-ray Spectrometer (MaGIXS), which observed
several strong emission lines in the 8 to 30 {\AA} wavelength range from two
X-ray bright points and a portion of an active region. In this paper, we
present a systematic investigation of the parameters that control and optimize
the inversion method to unfold slitless spectrograph data.
