Picasa Web Albums
Change Auto Backup upload setting between full & standard size
You have control over whether your uploaded and Auto Backup photos are stored at standard size, which is great for sharing on the web, or full size print quality, which uses more storage space. You can upload an unlimited amount of standard size photos, but full size photos will count against your Google Drive storage quota.
To see instructions, choose your device:Android
From the Google+ app, touch Menu > Settings > Auto Backup > Photos size > Full size or Standard size.
From the Google+ app, touch Menu > gear icon > Camera and Photos > Auto Backup > toggle Full size Backups on or off.