A small glossary of photo restoration

Restoration guides, scanner manuals and conservators all speak a compact dialect — emulsion, halftone, archival, DPI — that assumes you grew up in a darkroom. This glossary translates the terms you will actually meet while rescuing a family archive, in plain language and without the chemistry lecture. Each definition sticks to what the word means for your photos in practice.

How to use these terms

You do not need this vocabulary to restore a photo — upload a scan and the work happens regardless. It earns its keep when you read about your photos elsewhere: dating a print by its process, understanding why the scanner asks about DPI and descreening, or following a conservator’s advice without translating every second word.

The definitions favor the family-archive context over technical completeness. Where a term means several things in photography at large, we give the meaning you will meet while scanning and restoring old prints.

Colorization: Adding reconstructed color to a black-and-white photograph. The original never recorded color, so colorization is an informed inference from texture and context — plausible rather than documentary, and best treated as an interpretation of the image.
Upscaling: Enlarging a digital image beyond its original pixel size while reconstructing detail, so a small print or coarse scan does not turn into visible blocks when it is enlarged. Modern upscaling generates plausible fine detail rather than just stretching pixels.
DPI: Dots per inch — the resolution setting when scanning (strictly PPI, pixels per inch, but scanner software says DPI). 600 DPI is a sound choice for small prints; below 300 the scan starts discarding detail that no later step can recover.
Film grain: The fine, sand-like texture of film photographs, formed by the clumps of silver (or dye) that make up the image. Grain is part of the photograph’s character, not damage — good restoration cleans scratches without steamrolling grain into plastic smoothness.
Sepia: The warm brown tone of many old photographs. Often it was applied deliberately — sepia-toned prints resisted fading better and the color was fashionable — though similar warmth can also creep in as paper and image age.
Silver gelatin print: The standard black-and-white photographic print of the twentieth century: paper coated with gelatin holding light-sensitive silver. If your family archive has black-and-white prints from roughly the 1910s to the 1980s, they are almost certainly silver gelatin.
Vignette: Darkening or fading toward the corners and edges of an image. In old portraits it was often deliberate — a soft oval fade around the sitter was studio fashion; in snapshots it can simply be the lens. Epoha has no setting for it, so keep your original scan if the soft oval matters to you.
Negative: The developed film original in which tones are inverted — dark is light and light is dark. Prints were made from negatives, and a surviving negative usually holds more detail than any print made from it, which makes negatives the best scanning source when you have them. Epoha does not invert negatives, so turn the frame into a positive in your scanner software or a phone app before uploading.
Contact sheet: A print made by laying film strips directly on photographic paper, producing one small positive of every frame on the roll. Photographers used contact sheets to choose which frames to enlarge; finding one tells you more frames existed than the prints you inherited.
Emulsion: The thin image-bearing coating on photographic paper and film — gelatin holding the silver or dyes that form the picture. It is the fragile layer: scratches, cracks along folds and water damage are all injuries to the emulsion rather than to the paper beneath.
Halftone: The printing technique behind photos in newspapers and books: the image is broken into a grid of dots whose sizes simulate continuous tone. Scanned halftones tend to produce moiré interference patterns, and restoring one means rebuilding smooth tone from the dots.
Archival scan: A digitization made to preservation standards rather than for quick sharing: high resolution, no automatic corrections, saved in a lossless or minimally compressed format, and backed up in more than one place. The scan you make once so nobody has to rescan a fading print later.
Daguerreotype: The earliest common photographic process, introduced in 1839: a direct positive on a silvered copper plate, usually kept under glass in a small hinged case. There is no negative — every daguerreotype is one of a kind. The polished surface reads as a mirror at most angles and only shows the image clearly when tilted under soft, indirect light, which is worth knowing before you try to photograph or scan one.
Ambrotype: A one-of-a-kind photograph on glass, popular through the 1850s and 1860s: a thin, underexposed negative that reads as a positive once backed with black paint, paper or velvet, usually inside a small case. The image sits directly on the glass and can flake if the backing shifts, so handle it by the edges only. If the backing has come loose, photograph it as is rather than trying to reseat it.
Tintype: A photograph made directly on a thin sheet of blackened iron, not tin, common from the 1860s into the early 1900s and sold cheaply at fairs, on street corners, and by traveling photographers. Tintypes hold up better than glass formats but rust where the surface is scratched or the edges are bare metal. A magnet sticking to the plate is the fastest way to confirm you are holding one.
Albumen print: A photographic print made on paper coated with egg white and light-sensitive silver, the dominant printing process from the 1850s to the 1890s. Albumen prints often carry a warm yellow-brown cast and fine surface cracking as the coating ages, and they were almost always mounted on cardboard. That mount needs the same gentle handling as the print itself when you scan or store it.
Carte de visite: A small photographic portrait, roughly the size of a business card, mounted on card stock and traded among family and friends from the 1850s through the 1870s. If an inherited photo is that small and pasted onto thin cardboard, it is likely a carte de visite. The studio’s printed name, often stamped on the back, can help narrow down when and where it was taken.
Cabinet card: A photographic portrait mounted on card stock about the size of a small postcard, larger and sturdier than a carte de visite, common from the 1870s into the early 1900s. Studios often printed elaborate logos or decorative type across the mount, front or back, which is frequently the clearest clue for dating a family portrait and tracing which studio, and which town, took it.
Glass plate negative: An early photographic negative made on a sheet of glass coated with light-sensitive emulsion, the standard negative material from the 1850s until flexible roll film took over in the early 1900s. Glass plates are heavy and break easily, but the negative usually holds more detail than any print made from it — worth digitizing carefully if a box of them has survived in the family archive.
Nitrate film: An early flexible roll-film base used from the 1890s into the 1950s, chemically related to gun cotton and, unlike modern film, flammable and prone to slow chemical decay: sticky, discolored, or crumbling as it ages. Nitrate negatives are worth digitizing sooner rather than later, and are best kept away from heat, away from other film, and somewhere with reasonable air circulation.
Hand-tinting: Color applied by hand with dyes or oil paints directly onto a black-and-white print or plate, practiced from the earliest days of photography through the mid-1900s, before color film was common. Hand-tinting is a real, physical layer of paint on top of the image, and it can flake or fade unevenly with age. Epoha has no hand-tint mode: it reads such a print as a color photograph, and the tint may come back corrected or repainted, so the original scan stays the record of the tinter’s work.
Deckled edge: The soft, irregular border on some photo paper, produced on purpose by the paper-cutting equipment rather than caused by damage — common on snapshot prints from the mid-1900s. Recognizing a deckled edge as an intentional design choice means you do not need to trim it away, straighten it, or treat it as torn paper when you scan or restore the photograph.
Foxing: Small reddish-brown spots scattered across old photographs and paper, caused by humidity acting on trace metal impurities in the paper, by fungal activity, or by both — conservators still debate which cause dominates in a given case. Foxing appears as distinct dots rather than a solid stain or a soft, spreading discoloration, which is how you tell it apart from mold or plain yellowing. It cannot be scrubbed off; a scan and digital cleanup is the safer path.
Silver mirroring: A bluish, metallic sheen that shows up in the darkest areas of an old black-and-white print, often near the edges, as silver particles in the emulsion migrate to the surface after decades. It is a sign of age and chemistry, not mishandling, and it cannot be polished away without damaging the print underneath. Tilting the photo, or angling the light over your scanner, often reduces the glare enough for a clean scan.
Dye fading: The gradual loss of color in a chromogenic, dye-based color photograph as its dyes break down under light and time — unlike black-and-white silver prints, which fade far more slowly. Dye fading rarely loses color evenly: one layer typically fades first, so the whole print drifts toward red, magenta or yellow before it reads as simply washed out. Restoration can rebalance what remains, but it is reconstruction, not recovery of the original dye.
Fixer (hypo): The chemical bath — sodium thiosulfate, long nicknamed “hypo” — used near the end of darkroom printing to dissolve the unexposed silver and stop a photograph from continuing to change once it reaches the light. A print that was not washed long enough afterward keeps a trace of fixer trapped in its paper fibers, which goes on reacting for decades and eventually yellows or stains the image. It explains why two prints from the same year can age very differently.
Acid-free and lignin-free: Labels on photo storage materials — sleeves, boxes, mats, album pages — meaning the material will not release acids or lignin, a wood-pulp compound, that yellow and embrittle photographs sitting against them over time. Ordinary paper, cardboard, and sticky tape are usually acidic. Rehousing an old photograph in acid-free, lignin-free materials will not undo damage that has already happened, but it slows down whatever comes next.
Magnetic (self-adhesive) album: The style of photo album common from the 1970s through the 1990s, with sticky pages under a clear plastic sheet instead of mounting corners or slots — no actual magnet involved, despite the name. The adhesive hardens and yellows with age, sometimes bonding a print permanently to the page, and pulling it free can tear away the emulsion. If a photo is stuck like this, scanning it in place is usually safer than forcing it loose.
Moiré and descreening: Moiré is the wavy, rainbow-like interference pattern that can appear when you scan a printed photo made of tiny dots, such as a newspaper clipping or a magazine reproduction, because the scanner’s own grid clashes with the dot pattern underneath. Descreening is the scanning or software step that softens those dots before the pattern can form, trading a little sharpness for a clean, moiré-free image.
JPEG artifacts: Blocky squares, blurred edges, or a faint grid pattern visible in a digital photo, caused by the JPEG format discarding detail to shrink the file size — worse the more times a file has been re-saved and re-compressed. They show up most clearly in flat areas like skies or skin, and around sharp edges. Restoration can soften them, but the detail that JPEG compression threw away is genuinely gone, not merely hidden.
Inpainting: The technique — used by retouchers and AI tools alike — of filling a damaged or missing area of a photo by reasoning from the pixels around it, so a tear, hole, or stain ends up covered with plausible surrounding detail. What inpainting adds is a reconstruction built from context, not a recovered record of what was actually in that spot, which matters most whenever the missing area touches part of a face.
Identity drift: What happens when AI restoration changes a face enough that the person in the photo stops looking like themselves: a shifted jawline, altered eyes, a stranger’s smile in place of a familiar one. It tends to get worse as damage over the face increases, because the model has less real detail left to work from and more to invent. An honest restoration process warns you when a face is too damaged to trust and shows the result beside the original, so you can check for exactly this before calling a face repaired.