Just read in
a very short article that iOS 11 is switching from the h.264 video compression to HEVC (which is h.265) apparently for 4K video purposes, and switching from JPEG to HEIF which takes up half the space of JPEG, so more compressed. This switch is for devices running on an A9 or faster processor. No idea how accurate this info is.
I do like the iPhone 7 photos for when i don't have a good camera along, but I rarely take any that I will want to post process into keepers. So since I rarely take iPhone photos I'm not too concerned about the compression or image quality. I am concerned about conversion though. I'm not familiar with HEVC or HEIF, but I really don't want to have to get a special app or two just to convert these new formats into something I can post on Facebook or send to someone via email.