Tormentfan: They are a pain in the arse to get, you just have to persevere.
kalirion: I took the photos, and the game won't recognize them. I'm not going to spend hours photographing the same guy over and over again until the game decides its a good photo - especially as I don't know when and how that decision is made. I have 4 of the anachronox symbols "officially collected", but 3 of them did not show up in the Collector's screen until I spoke to the museum guy. Looks like the red bipiris are even worse.
There is a small short-cut you can use if you want to find out if a picture "works":
*save your game
*go to your folder with the save-games
*go to the appropriate save-game and look around until you find your photograph data.
There should be an image and a .dat file for each photo in your camera: the .dat file contains a list of all "items" that your camera snapped. If it's empty, you know it didn't register. If it hits home, there should be at least a single entry for the bipidri.
You can open the .dat file with any good text editor,.
I used it to get the tenements one, since that one glitches a bit, this basically shortens your trip to the nearest save-point instead of going all the way back to the collector guy.
P.S. I'm not 100% sure but I think you can get all bipidri even late-game. There aren't any bipidri that "disappear" or become unavailable.