spoiler a pic?
As for pictures. I tend to create a "players aid" thread that have the pictures of specific things. For example the player received a sloppy, hand drawn, map that was covered in blood. If you looked closely at the picture there were indications of hidden things (doors and such). It wouldn't work as well by simply telling them, this was a completely visual clue.
By putting it in a separate thread it allowed the players to 1. Reference the clue at any time. and 2. Ignore it if they wanted to.