Legal Question in Criminal Law in California

Yes, they can charge it, but proving it is another thing. Showing yourself in a picture with other known gangmembers gives the appearance of being affiliated with a street gang, and thus the allegation of being in a street gang and committing a crime in furtherance of a gang would logically follow. Good luck.

Can they? Sure. Proving it for enhancement requires evidence, and the picture proves 'association', which is exactly what is required. There is an old cliche: we are judged by who we associate with.