Spot Removal and Clone Stamp data

Question

I understand that Ver 1.0 includes "non destructive" spot removal, clone stamp etc. How is this data stored? While I understand how image adjustments are stored as metadata in an XMP sidecar or DNG, if this data is simple text, how can changes to image content also be be stored in these files? As a new version of the RAW image data?

Answer 1

> "I hadn't realised that metadata could support such functions".
If you want further thoughts on what metadata could do in future, think of actions in Photoshop.
Imagine that you ran an action as you were editing a file, then instead of saving the changed image, you saved the original image with the action embedded in the file. Then, when you opened the file in future, Ps automatically ran the action. That would be an example of non-destructive order-dependent metadata.
Unfortunately, the restrictions on actions, such as not including brush-use, limits the value of such a method. But it is a way of thinking about this topic. (Note that Lr 1.0 holds the brush size in the clone/heal metadata, while Photoshop can't hold brush-use in actions! In that case, Lr is already ahead of Ps).
A very powerful feature of Ps is the layer mask. Being a greyscale image, it would not fit well into XMP metadata. Perhaps this is an example where Lr will "never" catch up. (Never say never!)
I've seen several people ask for localised editing in Lr. There are various possibilities for making selections for local editing other than using the full power of layer masks. In fact, a number of the standard ways of creating selections appear to have relatively simple parameters. (Standard marquee tools, select color range, etc. Even refine edges). But a Lr with too many of those in would compete strongly with Ps itself! Perhaps this will be driven by what the natural competitors to Lr do in future.