Was wondering the same thing, I have been unable to unlock two pictures in Deniz's gallery (#4.2 and #7) and have found no indication of how to unlock these in the downloadable walkthrough. Same goes for #4 and #7 in the Misc section of the gallery.
I have every picture now but Deniz 4.2 which I really don't understand how you get since I have seemingly tried every option.
Deniz picture 7 is a result of you romancing both Levon and Deniz at the same time.
The ones in the misc gallery are both achieved when you go to rescue the pig from the club but I can't remember the specifics of how you get them both.
Hey thank you! I just managed to unlock all the missing pictures - except for Deniz's #4.2. For the two misc ones, without giving away too many spoilers, you just have to try different options during the ball. I had unlocked a few but those two are exclusive to a secondary route (which still wins you a good ending if you play your cards right).