Darren Addy
EF5
I'm not sure what you mean by "RAW files in conversion". As I'm sure you know, programs like Aperture and Lightroom do non-destructive editing, meaning that the original RAW file remains unaltered and your transformations are taking place on a copy. This is a big change of thinking for users of Photoshop, as explained here:
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Non-destructive Editing
While Lightroom may not have all of Photoshop's editing features, it scores off Photoshop in one important regard. Photoshop has a mix of destructive and non-destructive editing features -- if you've used an Adjustment Layer in Photoshop, then you're familiar with non-destructive editing. However, all the edits you make in Lightroom are non-destructive. A non-destructive edit doesn't alter the original pixels in your image.
The advantages of non-destructive edits are that you can undo any edit at any time, and in any order, and you can go back and change the parameters of any edit at any time.
In a non-destructive editing system, your original master data file is stored alongside a list of the edits that you want made to the image. The image editor applies the list to the original master data on-the-fly, any time the image needs to be displayed, printed, or output to a file.
In Lightroom, this editing data is stored inside the application's Managed Photos folder, whether you choose to import your images into the managed library or leave them in their original locations and import them as references. (You can change the default location of the Managed Photos folder using Lightroom's Preferences dialog.) If you're working with raw files, you can also choose to have the edits and metadata changes stored in sidecar XMP files, just as you do in Bridge. To activate this feature, go to Preferences > File Management, and check the "Automatically write changes into XMP sidecar files" option.
Once you get used to the flexibility of a non-destructive editing system, it can be hard to go back to a destructive system. However, bear in mind that if you make edits in Lightroom, and then want to give a copy of the edited image to someone else, you must export a rendered, processed version that includes your edits. Your original image is never adjusted, so Lightroom needs to create a new image with your changes.
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