I started using Google Photos to backup all my photos in just standard resolution (their free version). Now I just changed my setting in the auto-backup utility on my Mac to store them in the full resolution. I also changed another setting under Google+ settings to store full resolution images as well. I also increased my Google Drive storage expecting this to rise dramatically. But my storage usage didn't change much at all after I changed to full res images, and when I compare the dimensions from my iPhoto library to the same photo in Google Photos it doesn't match. Google photos version has smaller dimensions.
Do I need to re-upload my whole library to Google Photos? If so, how would I do that? If not, then why isn't it updating my photos to their full resolution?