This function has in game or I need another app ?
You would need to download a separate app for that, yeah. It's very easy to find (just do a forum wide search for "gallery unlocker" on here) and just as easy to use. It
can cause some weird issues though, like missing or corrupted images, so I would recommend copying your game folder
before using the unlocker, and then using the unlocker
only in the copied folder. That way, your original folder remains intact and uncorrupted.
Oh, and don't worry about having to keep the copied folder; you can just delete that one after you have unlocked every scene in the gallery. (It might also be worth noting that you may need to actually "play through" each scene individually, at least for CIC, in order to keep the scenes permanently unlocked. That may be what causes the aforementioned errors, which is why I recommend copying the game's folder first.)
Hope that helps. Enjoy!
-Mal