As announced yesterday, Google Photos is now ready to offer you an option to downgrade your photos and reclaim some storage space in your account. The option has gone live on https://photos.google.com/settings and will let you convert all photos you had uploaded in Original quality to High Quality (maximum 16MP). Given that the latter don't count toward your Google storage and the former do, this will allow you to save whatever space you had lost on photos while still keeping them stored in your account. Better yet, in our previous review of Google Photos, Alex had concluded that there is no detectable quality loss when switching to High Quality uploads, so you're not likely going to lose anything by activating the conversion.
The process is fairly simple. You click on Recover Storage, agree to Compress even though that will lead to all photos being converted on all of Google's services, then agree one more time just to be sure, and you'll see that the compression has started. The screenshots below show the different steps.
Google says the process will take about an hour, it's all done server-side without any change affecting your computer or phone. I've been at it for a couple of hours and it seems that the conversion stopped short of 800MB for me. I reclaimed 9.4GB of space by triggering the compression, but the last few hundred Megabytes just don't want to switch over. That must be a bug or the servers could be hammered by everyone using the option simultaneously.
I have taken a quick look through my photo albums and collections and it seems like everything is intact, as it should be. Photos that were compressed look just the same as their previous version and I can't spot any visible change in quality or detail. Plus I now have 213.8GB of free storage on my Google account instead of 204.4GB. It might not sound like a lot, but it will make a difference once my 2 free years of storage courtesy of Chromebook are over. The best part is that I didn't have to delete and re-upload everything because that would have been a huge pain.