Surface brightness vs. magnitude in four different bands. Red empty squares indicate spectroscopically identified Virgo cluster members, blue empty triangles background galaxies with spectroscopic redshift z_spec < 0.1, green empty circles objects with photometric redshift z_phot < 0.1, black crosses galaxies with SDSS data but without spectroscopic or photometric redshift, small magenta dots objects identified as stars in the SDSS and small cyan 3 branches stars GALEX detections without SDSS counterparts. The dashed line indicates the surface brightness vs. magnitude limit used for discriminating Virgo members from background objects. The dotted lines indicate the limit in surface brightness adopted for selecting galaxies in the UV blind survey.