Stains, lifted, the paper survives.

First decide whether anything is actually missing. Damage to a print falls into two categories that look similar on screen and behave completely differently. A tint — the brown of an ageing silver print, the magenta cast of a nineteen-seventies colour photograph, a yellowed varnish — sits over an image that is entirely intact, and the correct fix is a colour adjustment that touches no detail at all. A stain is different: damp, mould, adhesive or a spilled drink has chemically changed the emulsion, and the picture in that area no longer exists to be recovered. Only the second is a mask job. Zoom to 100% and look for surviving structure inside the discolouration; if you can still make out a collar or a doorway through the brown, mask nothing there and spend nothing.

Foxing is the friendly case; a tide-mark is the demanding one. Foxing — the constellation of small rust-coloured spots that damp paper grows — is a scatter of tiny holes each ringed entirely by good picture, and the fill closes them so completely that the print reads as clean. A water stain is the opposite shape: one large, irregular, soft-edged region that can cover a quarter of the frame, and the model must author every pixel of it from the intact border. Over a plain studio backdrop that goes well. Over a patterned wallpaper it goes approximately. Over a group of faces it goes wrong in the particular way that people notice, because a face averaged from other faces is nobody.

Mask generously at the edges and sparingly over people. Stains have soft boundaries where the damage thins out rather than stops, so a mask drawn on the obvious brown leaves a pale halo that the fill blends into. Take a few pixels past the visible edge everywhere. Then do the opposite over faces: pull the mask back to the hairline or the jaw and leave features alone, because there is a model on this site actually trained to rebuild them. Run the cleaned image through face restoration afterwards and it will bring back eyes and mouths with an identity check against your original, which is a far better outcome than an inpainted guess. Line damage — a crease, a scratch, a torn edge — belongs to scratch removal, which is a thin mask and an easier problem, and anything sitting on top of the print rather than in it — a drawing pin, a sticker, a corner mount — is straightforward work for the object remover.

Keep the evidence, and know the terms. Whatever you decide to clean, archive the raw scan untouched and name every derivative so that in twenty years the difference between the document and the restoration is obvious. Colour comes last if the print is black and white, through the colourising tool, and file size for sharing is on-device work in the image compressor, which uploads nothing. Stain removal itself is Cloud HD: Pro-only, opt-in, processed on our GPU in the United States, with the scan and mask encrypted in transit, deleted when the run finishes and in all cases within 24 hours, and never used to train anything. Pro includes 150 runs a month on Monthly and 200 on Annual, of which 10 may be HD runs.