Okay, this is probably some really simple problem that I can't figure out. See the attachment for what I am trying to achieve.
How do I make the logo, or any vector for that matter, do this positive/negative thing when placed over images?
I placed the vector on a separate layer in InDesign, colored it white, and set the transparency to Difference or Exclusion. The vector appears black over the light colored background, but over the dark background it appears a gray.