I have my Nexus5 set up to automatically back up my images to Google photos. On my phone there are 2 options for backing up photos:
Great visual quality at reduced file size (free unlimited storage)
Full resolution that counts against your quota
I am currently using the High quality setting.
I decided to perform a spot check of a photo on my phone vs. the same photo online:
- Phone - file size 1.71MB
- Online - file size 1.18MB
Then I compared the stats of the photos in Windows explorer - both are identical:
How is Google reducing the file size for the backed up photo?