I looked at what you sent me. You asked about the appearance of the cast/crew sigs - "looking brand new, looking signed yesterday etc. The crew and first Bergman sigs all look as they do because they are printed in the photograph - not live signatures (see color comment below), so as long as this photograph was stored well it will age well. From closed results at RR and so on, and some 1947 Bergman sigs, this blue ink Bergman looks fine. This scan appeared oddly de-saturated (inks) when I first looked, but of course they are all preprints, apart from the one signature inside the image. I see double weight and glossy but I would have guessed sepia toned pearl finish gelatin silver. I see Jack P. Pierce the makeup wizard among the preprints (Frankenstein, Dracula, Wolfman, Mummy etc).
Ingrid Bergman, a long-time favorite. Even forgetting Casablanca, Gaslight is pretty high up on my list of classic films and she is simply amazing in it.
I couldn't begin to look at the border signatures, but the Bergman autograph on the photo part itself screams authenticity.