Copyright law states that copyright belongs to whoever took the image and only they have the sole and exclusive right to sell, publish, enter contests and reproduce that picture.
The only exceptions are:
- Where a ‘work-for-hire’ contract is signed by the photographer.
- The photographer is an employee of the company the images are taken for.
So even if your friend took a picture of you with your camera, they own the photo copyright.
Note: If you suspect that one of your photos has been placed on internet without your permission, then do a reverse image search for it via Tin Eye.