Scanning and Archiving Antique Photographs: A Digitization Primer

Every physical photograph is slowly deteriorating, whether from silver tarnish on a daguerreotype, flaking emulsion on a tintype, or acid burn from an old paper mount. Digitizing a collection doesn't stop that deterioration, but it does create a record that will outlast it — provided the scan is made at a resolution and in a format that will still be useful decades from now. This is a starting point for doing that well, not a substitute for a professional conservator when an object is especially rare or fragile.

Choosing a resolution target

Resolution for a digitized photograph is usually specified in dots per inch (DPI) relative to the original's physical size, and the right number depends heavily on how small the original is. For a standard cabinet card or carte de visite, 300–600 DPI is a common working range, enough to capture genuine detail without producing an unwieldy file. For small cased images — daguerreotypes, ambrotypes, and tintypes, which are often only a few inches across at most — many archivists scan at 1200 DPI or higher, because a small original leaves very little pixel budget to work with even before considering any future enlargement.

Why small originals need disproportionately high DPI

Because print size is simply pixel count divided by DPI, a 2 by 3 inch tintype scanned at 300 DPI yields only 600 by 900 pixels total — barely enough for a same-size reproduction and nowhere near enough to support a meaningfully larger print later. Scanning that same object at 1200 DPI instead yields 2400 by 3600 pixels, giving you four times the linear resolution and considerably more room to crop, examine closely, or enlarge for study or display without the image falling apart into visible pixels.

Reflective versus transmissive originals

Daguerreotypes and tintypes are opaque, reflective objects, so they need to be scanned or photographed with light bouncing off the surface — a flatbed scanner's reflective mode, or careful copy photography with controlled lighting to avoid glare off a daguerreotype's mirror-like surface. Ambrotypes, being glass, can sometimes be scanned in either reflective or transmissive mode depending on whether you want to capture the finished positive appearance (with its backing) or study the underlying negative image, which is occasionally useful for close examination.

Handling originals safely during the process

Fragile, deteriorating originals deserve careful handling throughout scanning: clean, dry, lint-free cotton gloves prevent skin oils and fingerprints from reaching bare glass, metal, or delicate emulsion surfaces, and a stable, flat work surface reduces the risk of a scan session becoming the event that finally damages an heirloom. Cased images in particular can have loose components — a cracked cover glass, a preserver frame that's come apart — that are easy to disturb if handled quickly or without a plan for reassembly.

File formats and long-term storage

For archival purposes, saving an uncompressed or losslessly compressed master file (typically TIFF) alongside a smaller, more widely compatible copy (typically JPEG) gives you both a preservation-quality original and a convenient file for everyday sharing or printing. Keep the master file backed up in at least two physically separate locations, since a scan is only as durable as the storage behind it — a hard drive failure can undo a careful digitization project just as thoroughly as a fire could damage the original object.

Physical storage still matters

Digitizing a collection is not a reason to neglect the physical originals: acid-free archival sleeves and boxes, stored away from direct light, high humidity, and temperature swings, remain the standard way to slow further deterioration of whatever you're not ready to part with. A digital scan and a well-stored original work together — the scan makes the image accessible and shareable, while proper physical storage protects the artifact itself for as long as possible.

Planning before you scan

It's worth deciding upfront the largest size you might realistically ever want to print or display an image, and scanning at a resolution that comfortably supports it, rather than reaching for the original a second time later — each additional handling session is itself a small risk to a fragile object.

Our Print DPI & Size Calculator works in both directions: check what print size a given scan supports, or work out the pixel dimensions you'll need to hit a specific target size at your chosen resolution.