Having trouble identifying an older crime/art-related movie about a photographer witnessing a crime

So, the movie I'm thinking of, I can't think of every detail, but here are the details i can remember:

-The protagonist is a kind of artsy photographer (there are ladies in his studio the entire film long, going there to be photographed)

-One of the biggest conflicts in the movie revolves around him having taken and then blowing up to a very large size, a scene of a park in which a crime was committed.

I BELIEVE the movie was in black and white. In fact, i'm almost 100% certain of that.