I've uploaded some photos that were scanned from medium-format transparency film, and, given that they were old images and I was uncertain how scanned film would work with QC, I bypassed it by using the "Archival Upload" option.
Later on, after reading some threads here, I uploaded some images from the same camera/film/scanner as regular stock images and they passed QC.
Of course, the ones designated as Archival include the proviso, "This image could have imperfections as it’s either historical or reportage."
Member Services has advised me that designations cannot be changed, so I