Samsung's 5th-generation Android-based Galaxy smartphone was released April 11, 2014. Improvements to the phone include a fingerprint scanner, updated camera, larger display, and water resistance. It is available in four different colors; black, blue, white, and copper.
Is it really black pixels or is it dust on the lens? Try to smack the phone around a bit and see if the "black pixel" moves. If it moves to a different spot, then it's dust. If it does not move, then you may need to replace the rear camera.