How to Colorize a Black-and-White Photo on iPhone, Offline and in Seconds

TL;DR

ReColor runs a colourisation model that is stored in the app, adds colour to the photo and keeps your original detail. It works offline and takes a few seconds per photo. Free: 3 colourisations a day, with exports capped at 1280 px and watermarked.

The problem

Colourising an old photo by hand takes real skill and hours per picture, and the results still involve guessing. The quick alternative, an online colouriser, means uploading a family photo to a stranger’s server, usually behind an account, often with a watermark or a limit, and sometimes with a processing queue.

How ReColor does it

The colourisation model is bundled in the app (about 250 MB), so there’s nothing to download and no connection needed. It works like this:

  1. The model looks at the photo’s brightness and predicts the colour (the chroma channels).
  2. ReColor merges that colour with your photo’s original full-resolution brightness, so fine detail isn’t blurred by the model.
  3. The result appears for you to compare with the original.

Photos with a very long side are first scaled to a maximum long side of 4096 px, which bounds the memory and time.

Steps

  1. Open ReColor and tap to add a black-and-white photo from your library.
  2. Wait a few seconds while the colour is generated.
  3. Drag the before/after slider to compare, and zoom in on faces.
  4. Save or share. See saving and sharing.

The free plan

  • 3 colourisations per day. Home shows “X of 3 free today”. Only finished ones count, and it resets at local midnight.
  • Exports are watermarked and capped at 1280 px on the long side. Pro exports at full size with no watermark.

For the best result

  • Start from the best scan you can get. See preparing old prints.
  • Check faces and clothes first. That’s where colour mistakes are most noticeable.
  • Expect a plausible result, not the truth. The model has never seen your grandmother’s dress.

FAQ

Does it need internet or an account? No. The colourisation model is inside the app (about 250 MB), so it works in airplane mode and nothing is uploaded.

How many photos can I colourise for free? Three finished colourisations per day, counted from local midnight. Pro is unlimited.

Will it make my photo lower quality? The model only predicts colour. Your photo’s original brightness detail is kept and the colour is merged back in at full resolution, up to a 4096 px long side.

Are the colours real? They’re a realistic guess, not the original colours. See the guide on colours that look wrong.

The app ReColor →