  We present a detailed procedure for treating data cubes obtained with the
Near-Infrared Integral Field Spectrograph (NIFS) of the Gemini North telescope.
This process includes the following steps: correction of the differential
atmospheric refraction, spatial re-sampling, Butterworth spatial filtering,
'instrumental fingerprint' removal and Richardson-Lucy deconvolution. The
clearer contours of the structures obtained with the spatial re-sampling, the
high spatial-frequency noise removed with the Butterworth spatial filtering,
the removed 'instrumental fingerprints' (which take the form of vertical
stripes along the images) and the improvement of the spatial resolution
obtained with the Richardson-Lucy deconvolution result in images with a
considerably higher quality. An image of the Br{\gamma} emission line from the
treated data cube of NGC 4151 allows the detection of individual ionized-gas
clouds (almost undetectable without the treatment procedure) of the narrow-line
region of this galaxy, which are also seen in an [O III] image obtained with
the Hubble Space Telescope. The radial velocities determined for each one of
these clouds seem to be compatible with models of biconical outflows proposed
by previous studies. Considering the observed improvements, we believe that the
procedure we describe in this work may result in more reliable analysis of data
obtained with this instrument.
