Postage Stamp Overprint Isolation

I have a series of postage stamps whose overprints need to be lifted from the underlying design so they can stand alone for study and publication. You will receive high-resolution scans (600 dpi TIFFs) of each stamp; I need the overprint from every image returned on a transparent background, perfectly aligned to the original pixel grid and true to the stamp’s printed colour.

Please keep edge detail sharp, avoid haloing, and deliver either layered PSD files (background + isolated overprint) or individual PNGs—whichever workflow you prefer—as long as the overprint sits on its own layer. A short note on your masking or vector-tracing approach plus one processed sample from my test scan will serve as the proof of concept before we move to the full batch.

Once the sample is approved, you can tackle the remaining images in one or two milestones. Accuracy matters more than speed, but a realistic turnaround time would be appreciated.