  Surface photometry data on 90 dwarf irregular galaxies (dIrrs) in a wide
vicinity of the Virgo cluster and 30 isolated dIrrs are presented. Images from
the Sloan Digital Sky Survey (SDSS) are used. The following mean photometric
characteristics (color and central surface brightness) are obtained for objects
in the two samples:(V-I)o=0.75 mag (sigma=0.19 mag), (B-V)o=0.51 mag
(sigma=0.13 mag), SBv=22.16 mag/sq.arcsec (sigma=1.02 mag/sq.arcsec) for the
dIrrs in the vicinity of the Virgo cluster and (V-I)o=0.66 mag (sigma=0.43
mag), (B-V)o=0.57 mag (sigma=0.16 mag), SBv=22.82 mag/sq.arcsec (sigma=0.73
mag/sq.arcsec) for the isolated galaxies. The mean central surface brightnesses
for the isolated galaxies in this sample is lower than for the dIrrs in a
denser environment. The average color characteristics of the dIrrs in the
different environments are the same to within ~0.2 mag.
