You can mannually change the brightness and what thing in Google Photos application?
Answers
Edit Google photos
Add filters, crop photos, and more on your mobile device or computer.
Tip: If you have back up & sync turned on, your edits will sync to your Google Photos Account.
Android ComputeriPhone & iPad
Before you get started
Download and install the Google Photos app.
Tips:
While you edit a photo, the icons turn blue to show that you have applied a certain feature to the photo.
To compare your edited photo to the original, tap and hold the image preview.
To undo changes to an edited photo, tap Edit   Revert. You can't undo changes to photos you save as a copy.
After you edit a photo, to save changes, at the bottom right, tap Save. You may find two options on how to save:
Save: Saves your changes to the original photo. You might not be able to use this option for certain edits.
Save as copy: Makes a new photo with your edits and doesn’t change the original.