With all of the tools available, including post-production enhancements, the sky is now the limit for the photographer. What once belonged to the painters, now is shared with the photographers and the photographic designers.
Abstract Photography: First Definition
As is the case where beauty is in the eye of the beholder, so is the definition of abstract photography.
To some it is a case of the definition of what someone is viewing, in the photograph, has no words to describe it. It is probably fair to say that if it cannot be defined or described, it is abstract. The picture, below, is closer...