  We study the optical properties of a large sample of galaxies in low-density
regions of the nearby universe. We make a 5/h Mpc-smoothed map of the galaxy
density throughout the Center for Astrophysics Redshift Survey (CfA2) to
identify galaxies within three prominent nearby ``voids'' with diameter >30/h
Mpc. We augment the CfA2 void galaxy sample with fainter galaxies found in the
same regions from the deeper Century and 15R Redshift Surveys. We obtain B and
R CCD images and high-S/N longslit spectra for the resulting sample of 149 void
galaxies, and also for 131 galaxies on the periphery of these voids.
  Here we describe the photometry for the sample, including B isophotal
magnitudes and B-R colors. For the 149 galaxies which lie in regions below the
mean survey density, the luminosity functions in B and R are well-fit by
Schechter functions with respective parameters (alpha_B = -0.5 +/- 0.3, B_* =
-18.9 +/- 0.2) and (alpha_R = -0.9 +/- 0.3, R_* = -20.4 +/- 0.3). The B
luminosity function (LF) is consistent with typical survey LFs (e.g., the
Southern Sky Redshift Survey), and the R LF is consistent with the Century
Survey. The B and R LFs of 131 galaxies in the ``void periphery'', regions
between the mean density and twice the mean, have similar Schechter parameters.
The CfA2 LF is inconsistent with both samples at 3.5-sigma.
  When we narrow our analysis to the 46 galaxies in regions below half the mean
density, the LF is steeper: alpha = -1.4 +/- 0.5. The typical survey LFs are
inconsistent with this subsample at 2-sigma. The B-R color distribution of
galaxies in the lowest-density regions is also shifted significantly (3-sigma)
blue-ward of the higher density samples. The most luminous red galaxies (R <
-21) are absent from the lowest density regions at 2.5-sigma.
