The Spitzer Survey of Stellar Structure in Galaxies (S$^4$G): Precise
  Stellar Mass Distributions from Automated Dust Correction at 3.6 microns
  The mid-infrared is an optimal window to trace stellar mass in nearby
galaxies and the 3.6$\mu m$ IRAC band has been exploited to this effect, but
such mass estimates can be biased by dust emission. We present our pipeline to
reveal the old stellar flux at 3.6$\mu m$ and obtain stellar mass maps for more
than 1600 galaxies available from the Spitzer Survey of Stellar Structure in
Galaxies (S$^{4}$G). This survey consists of images in two infrared bands (3.6
and 4.5$\mu m$), and we use the Independent Component Analysis (ICA) method
presented in Meidt et al. (2012) to separate the dominant light from old stars
and the dust emission that can significantly contribute to the observed 3.6$\mu
m$ flux. We exclude from our ICA analysis galaxies with low signal-to-noise
ratio (S/N < 10) and those with original [3.6]-[4.5] colors compatible with an
old stellar population, indicative of little dust emission (mostly early Hubble
types, which can directly provide good mass maps). For the remaining 1251
galaxies to which ICA was successfully applied, we find that as much as 10-30%
of the total light at 3.6$\mu m$ typically originates from dust, and locally it
can reach even higher values. This contamination fraction shows a correlation
with specific star formation rates, confirming that the dust emission that we
detect is related to star formation. Additionally, we have used our large
sample of mass estimates to calibrate a relationship of effective mass-to-light
ratio ($M/L$) as a function of observed [3.6]-[4.5] color: $\log(M/L)=-0.339
(\pm 0.057) \times ([3.6]-[4.5]) -0.336 (\pm 0.002)$. Our final pipeline
products have been made public through IRSA, providing the astronomical
community with an unprecedentedly large set of stellar mass maps ready to use
for scientific applications.
