How to add camera settings to a photo

Some phone camera apps stamp a line under the picture with the aperture, shutter speed, ISO, focal length and camera model. Doing the same for camera files or older shots raises three questions: where the numbers come from, how to add them, and why some photos give you nothing.

Hands-on version: Online camera settings watermark generator — the three-step flow with interface screenshots, a before/after pair and the failure cases people actually hit.

1. Where the numbers come from: EXIF

Every camera and phone writes a block of metadata called EXIF next to the pixels. It records what happened during the exposure:

A settings watermark reads that block and draws it onto the picture. A file that reads nothing has lost the block somewhere along the way.

2. Why they vanish when you send a photo

Messaging apps and some social clients re-encode images on send, and the new file keeps almost no metadata.

Two ways to keep them:

• Send the original file, if the app offers it.
• Burn them in first. A watermark is pixels, and recompression can't strip pixels.

3. The three-minute workflow

The example uses Mark: a web app, no account, no upload. Everything runs in your own browser.

Step 1: start from a file that still has EXIF

Straight off the card, or the original in your camera roll; not a copy saved out of a chat. JPEGs from a raw converter normally keep full EXIF. The web app can't read HEIC, so convert iPhone shots to JPEG first.

Step 2: drag it in

Open mark.lenscript.cn and drop the photo in. Model, lens, aperture, shutter speed, ISO, focal length and date are read from EXIF.

Step 3: pick a template and download

Pick a template on the left, then switch off the lines you don't need under Show in the top bar. Model plus one line of settings is often enough. Hit Download; JPEG and PNG both export at full resolution.

Open Mark and try one

4. Making it look good

Settings watermarks usually go wrong in one of four ways:

• The border is too wide. Keep it to 6–10% of the short edge; past 15% it competes with the picture.
• The type is too big. It's a footnote, meant to be read up close.
• Everything is switched on. Model, lens, settings, date, signature and logo run the full width of the frame. Two or three lines will do.
• The border fights the image. A wide white frame around a dark photo is harsh; pick a grey or dark-framed template.

Quick test: shrink the result to phone size. If you see the watermark before the photo, it's too much.

5. When nothing can be read

1. It's a copy from a messaging app. That's the usual culprit.
2. Your editor wiped it. Lightroom, Capture One and Darktable keep EXIF by default; some phone editors, watermark removers and online compressors don't. Compare the original and the edit. If the settings survived in XMP, Mark reads them from there.
3. It's a screenshot. Screenshots are new pixels; there was never an exposure.
4. It's an adapted lens. Manual glass has no contacts, so the body doesn't know what's mounted and often records the maximum aperture. Mark can't take a typed-in lens or aperture; switch the wrong line off under Show.

With neither EXIF nor XMP, the settings are gone. You can only type in the camera model, in the per-photo model fallback field: it applies when the file has no model, to the current photo only, and is never written back to the file.

6. FAQ