Paper applications need 2 identical photos, printed in colour on plain white photo paper with no border.
Plain cream or light grey background; no sunglasses or tinted glasses.
Leave both sides unmarked unless one photo needs to be countersigned, and send them loose.
How to do it with Requisito Listo
Open the «UK passport photo (printed)» template in the app.
Take the photo with the on-screen guide (or pick one from your gallery).
The app centers your face, makes the background white and gets the exact size and file weight.
Check the checklist, then upload or save it.
At the end you'll see a checklist: size, file weight, background and format. If something doesn't comply, it tells you what to fix before the portal rejects it.