Yes, edits are non-destructive: Waterlogue always works with your original image. When you save a .waterlogue document, Waterlogue also saves your original file data and always uses that when re-opening the document.
Waterlogue will also sensibly optimize the size of your .waterlogue documents:
- For large source images: If your source image is a 500 MB Photoshop file, Waterlogue will store a smaller, loss-less TIFF version of your image in the .waterlogue document rather than the Photoshop file.
- For small source images: If your source image is a 1 MB JPEG file, Waterlogue will store the source JPEG data in the .waterlogue document because it's the smallest, best representation of your image.