Why does Lightroom create a new copy of the image before editing it by another program?

Question

Why does Lightroom always create a new copy of the image whenever I edit the image with a 3rd party plugin? Why not just add an option to let you choose if you want to use the original raw file, supposing that the 3rd party utility can handle raw files?

Shouldn't this be better than creating a new large TIFF file?

A possible reason is that Lightroom won't save the history (steps) of edit that was done by the 3rd party tool. However, if I'm okay with that, what other reasons prevent just editing the raw?

Answer 1

Great question!

The best way to think about the workflow is by understanding that Lightroom doesn't edit the RAW file. Instead, Lightroom saves a series of alterations that it has applied to the RAW file, hence non-destructive editing. The RAW file itself is unaltered and Lightroom is saving the adjustments in its own file. When you export to make changes in a 3rd party program, Lightroom needs to combine the RAW file, along with the changes you've made, into a single file for the 3rd party software to edit. This new file is often a TIFF because that is the most universal lossless file type. If Lightroom applied the alterations to the RAW, then it would no longer be the "raw" file.