Pixelmator Photo lets you edit photos directly, without having to import them. All the edits are applied nondestructively, meaning, you can revert to the original photo or tweak any of the applied adjustments whenever you want. If you're not looking to save the nondestructive edits for later, you can also work destructively, overwriting the original photos. You can choose the editing workflow you prefer in Pixelmator Photo preferences.
Editing nondestructively preserves all the changes you make to a photo (color adjustment settings, crop, and repairs), so you can always come back and fine-tune them or revert the photo to the original.
Nondestructive editing in Pixelmator Photo is made possible by the special .photo-edit files. These files are linked to the photos you're editing and store information about the edits applied to them. These so-called linked files can be saved locally on your iPad, or in a dedicated "Linked Files" folder in iCloud.
When you delete a photo, it is deleted together with its linked file.
Important: Deleting linked files of the photos stored in the Files browser (On My iPad, iCloud, or other locations) will merge any changes applied using Pixelmator Photo. These changes cannot be reverted. This doesn't apply to Photos – the changes can always be reverted there, even after the linked files are deleted.
Editing destructively applies all the changes you make to a photo directly and no nondestructive settings are preserved. This applies to all regular image formats such as JPEG or PNG. To edit RAW images stored in Files, Pixelmator Photo needs to open them in its proprietary file format – .photo. This file format always preserves the changes you make to a photo, so the nondestructive settings are saved.
Important: The edits you make to the photos opened from Files or any location other than Photos are irreversible. Pixelmator Photo doesn't import photos but edits them directly, so any changes you make within the app will reflect in the actual location the photos are saved to. For instance, if you delete a photo in Pixelmator Photo, it will be deleted from the folder in Files where it was originally saved.