Samsung
Add a Photo to a Contact auf Samsung
On Samsung phones, every contact without a saved picture falls back to either the first letter of the name or one of the built-in default images, some of which are animated. This is a display default of the Contacts app, not a limitation of your account or SIM card. Once you assign a real photo, it replaces that placeholder everywhere the contact appears: incoming calls, the dialer, Messages, and notifications.
To set a custom photo, open Tap on Contacts ➔ Choose a Contact ➔ Tap on Edit ➔ Tap on Photo. From there you can pick Choose Gallery or Camera to either select an existing image or take a new one on the spot.
After picking an image, use Select a Photo and then Adjust the Photo and tap Done to crop it into the circular frame used for contact pictures. Finish with Tap on Save to store the change.
If the photo does not show up right away in the call screen, the contact list may need a moment to refresh, or the app might be caching the old default image. Reopening the Contacts app usually clears that up. This method only changes the local photo on your device; it does not sync to the other person's phone or to any cloud contact service unless you have contact sync enabled separately.