Comparison between our processed SDSS images and the deep images from the STSS (see Sect. 2.4.1) for the spiral galaxies (from left to right) NGC 5055, NGC 4651, NGC 1055, and NGC 1084. Top row: Images taken from Martínez-Delgado et al. (2010). Bottom row: This work, using SDSS data, after processing as described in Miskolczi et al. (2011), stacking g-, r-, and i-band images. Even at the shallower depth reached by the SDSS, high-confidence detections can be made with our technique. North is up, east to the left.