What to change, and what must not be touched.

01 · The lineDamage is what happened to the photograph. The face is who the person was.

Restoration work divides into two things that look similar in a portfolio and are not remotely the same.

Repair removes things that are there and should not be: a crease across the corner, dust, foxing spots, a tear in the margin, the yellow cast of a print that sat in sunlight, the shadow of the phone that photographed it. Every part of the original subject survives. The work is subtraction.

Alteration changes the subject: a smoothed cheek, a narrower jaw, whiter teeth, a removed mole, a changed hairline, a softened squint. The work is invention, and it is aimed at the one part of the image everybody in the room is an expert on.

02 · Fair gameThings that are almost always right to fix.

• Creases and folds, including the ones running through a face — these are physical damage to the paper, not to the person.
• Dust, speckling and foxing — the brown spots that appear on old prints.
• A colour cast. The pink or cyan drift of a 1970s print is fading, not skin tone. Correcting it restores the person's actual colour.
• Glare and reflections from photographing a framed print.
• A date stamp in the corner, and the crop marks of a lab print.
• Something distracting behind them — a bin, a doorway, a cluttered shelf. Removing it is not altering the person.
• Softness and moderate blur, within reason. Sharpening is subtraction. Inventing detail where the focus failed is not.
• A scratch through clothing or a background.

03 · Leave aloneThings that should stay exactly as they are.

• Moles, scars, birthmarks and anything else that was part of the face.
• Glasses, including the glare on them. Removing glasses changes who the person was.
• A squint, a lazy eye, a crooked tooth, a gap. These are the details people remember, often fondly.
• Lines, and the shape of the jaw, and the hairline. Age is not damage.
• The expression. A slightly tired or wry look is the person. A brightened, opened-up version of the same face is not.
• Whatever they are holding — a cigarette, a glass, a hand on a dog. Families sometimes ask for these to be removed. It is almost always a mistake, and always worth asking twice.
• Other people in the frame, unless there is no alternative.

04 · If you dislike somethingWhat to do when there is something you genuinely hate about the photograph.

Sometimes the honest answer is not to edit at all, but to change the use.

1. Print it smaller. An 8 × 10 on the guest book table is far more forgiving than a 16 × 20 on an easel. If a detail bothers you, reduce the size rather than the person.
2. Use a different photograph for the largest piece, and this one somewhere smaller.
3. Ask for one area to be worked on, not the whole face. A good retoucher can rebuild a torn collar without touching a cheek. Say exactly what bothers you, and ask them to leave the rest alone.
4. Ask for the untouched scan back. Always. It is your insurance: if you dislike the restoration, the original still exists and can be printed as it was.

If you are using an automated service, this is the one place where the tool matters more than the instructions. Systems that "enhance" faces tend to do it by default. Pinin is built to keep facial features where they are — what that means in practice — and the first restoration is free, so the cheapest way to judge any service is to run your worst photograph through it and look closely at the eyes.

05 · The proofHow to check a restoration before you print it.

Print a small test first. A 6 × 4 inch print costs almost nothing and shows more than a screen ever will, because the screen is backlit and generous and paper is neither.

Look at four things:

• The eyes. Hardness or perfect symmetry in the eyes is the clearest sign of a face that has been generated rather than recorded.
• The skin texture. Real skin at print size has variation. Smooth skin reads as plastic.
• The edges of the face against hair and background — where reconstruction gives itself away with a soft halo.
• The thing that is missing. Compare against the original and check whether a mole, a scar or a pair of glasses survived. This is the check almost nobody performs, and the one that matters most.

If the test print looks right at 6 × 4, it will look right at 16 × 20. If a face looks slightly wrong at 6 × 4, it will look badly wrong on the easel.