Is there any way to download only the pictures from the inbox of my Facebook account? I'm trying to make a collage from my fraternity and everyone has to send me pictures, but I need to download them all to my computer and I don't want to download them all one by one.
No, this isn't possible without programming via the Graph API (programming is out of scope for this site). You will also not find any third parties offering this service as the permission needed for approval requires the following
This permission is granted to apps building a Facebook-branded client on platforms where Facebook is not already available. For example, Android and iOS apps will not be approved for this permission. In addition, Web, Desktop, in-car and TV apps will not be granted this permission.
OK, might be stupid to answer this 3 years after the question was asked, but perhaps someone else needs it.
There's a browser extension that can save Facebook chats, including the option to save media as well. So you might just save the chat you need, and in the archived folder you will find all your pictures.
The link Messages Saver for Facebook