Syncing contacts from iCloud to iPhone

[protein]

Hey guys so I want to sync my contacts on iCloud with my iPhone but there's one thing stopping me from doing that. For some contacts, when synced from iCloud, their contact picture takes up the entire screen when I call them. For others though, it becomes a thumbnail. I've been trying to figure out why this happens but can't since it seems to happen to some large photos (4.5mb becomes thumbnail) and some lower resolution photos (kb becomes fullscreen). When the same photos are applied to contacts on my Mac's Address Book that's not synced to iCloud, all contact photos appear as a thumbnail when I call them.

I've done a few Google searches but I can't find a definitive answer so I'd like any suggestions on how to get all my contact photos to appear as a thumbnail on the call screen.

Thanks so much.