Don't have any idea. Was your phone dropped about the time that this started happening? Hopefully someone more knowledgeable will comment. Whether a factory reset would solve the issue, or a hardware issue which can't be repaired. Most unfortunate.
I'd do a a factory reset and it that doesn't solve the issue then it means you have bad hardware and th camera might of gotten damaged or faulty somehow. Are you still under warranty?
Welcome to Android Central! This only happens some time after you've already taken the picture? Are you backing your photos up to Google Photos? If so, does the image look like that when you go to photos.google.com on your computer browser?