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An image format that includes the original image as taken by the camera, but also a non-destructively applied and constrained set of alterations or filters

So you'd have the original photo data which is never changed, but then it procedurally adds the brightness/contrast changes, straightening/cropping, colour, blur/sharpening, etc.

People could look at an Instagram-style photo and compare to the original, and photo editors wouldn't have to keep multiple copies