Study of Galaxies in the Lynx-Cancer Void. IV. Photometric Properties
  We present the results of a photometric study of 85 objects from the updated
sample of galaxies residing in the nearby Lynx--Cancer void. We perform our
photometry on u, g, r, and i-band images of the Sloan Digital Sky Survey. We
determine model-independent galaxy parameters such as the integrated magnitudes
and colors, effective radii and the corresponding surface brightness values,
optical radii and Holmberg radii. We analyze the radial surface brightness
profiles to determine the central brightness values and scale lengths of the
model discs. We analyze the colors of the outer parts of the galaxies and
compare them with model evolutionary tracks computed using the PEGASE2 software
package. This allowed us to estimate the time T_SF elapsed since the onset of
star formation, which turned out to be on the order of the cosmological time
T_0 for the overwhelming majority of the galaxies studied. However, for 13
galaxies of the sample the time T_SF does not exceed T_0/2 ~ 7 Gyr, and for 7
of them T_SF < 3.5 Gyr. The latter are mostly unevolved objects dominated by
low-luminosity galaxies with M_B > -13.2. We use the integrated magnitudes and
colors to estimate the stellar masses of the galaxies. We estimate the
parameter M(HI)/L_B and the gas mass fractions for void galaxies with known
HI-line fluxes. A small subgroup (about 10%) of the gas-richest void galaxies
with M(HI)/L_B > 2.5 has gas mass fractions that reach 94-99%. The outer
regions of many of these galaxies show atypically blue colors. To test various
statistical differences between void galaxies and galaxies from the samples
selected using more general criteria, we compare some of the parameters of void
galaxies with similar data for the sample of 195 galaxies from the Equatorial
Survey (ES) based on a part of the HIPASS blind HI survey. abridged
