it means I can not take credit for the concept or idea, because Erik Johansson came up with the concept or idea, so dont tell me how smart I am for coming up with it because Erik Johansson was the one who is smart or brilliant, so credit is like kudos, or complements goes to him

It means that any praise or recognition goes to the photographer as he came up with the idea.

It means Erik Johansson deserves acclaims for this idea and also this idea belongs to him

The person is saying that the idea is not their own, but that it came from Erik Johansson. Therefore they want to acknowledge (express, confirm or admit) this fact, and say that "all credit goes to Erik Johansson." Credit can mean "public acknowledgement or praise," which is what is going on here. "All credit goes to him" means I am not taking credit for this idea, but saying that the credit/praise for the idea goes or belongs to Erik Johansson.