Scott Hampton wrote:
Anyway, is that why Apple did what it did with the RAW processing? You know, giving us the toggle switch to use the old RAW converter or the new RAW converter?
Scott
Why I'm glad you asked. [switches into instructor mode]
Let's say that you shoot a Pulitzer Prize winning photo (I say "you" because I'm not in danger of shooting one any time soon.) You process it with Aperture 1.5, which uses the "1.1" converter engine.
Fast forward to the future, and you're asked to send someone that shot. Assume this future is after Aperture has been updated with newer raw processing powers.
If Apple had not chosen to provide a path to previous conversions, when you went to export your file, it would use a different converter model to create that output. It would use whatever model was part of the current system.
What you'd end up with is a file that is NOT the original Pulitzer winning shot, but one that's processed using the current tools. While the assumption is that each new version of a processor would add to the ability of the raw file's decoding, even back in film when new developers would come out, people would stock up on the old chemicals so they could produce their images the way they originally seen it.
Now this might not be a big deal if the raw processing were to add better noise reduction, or more accurate colors, or some such, but if your client's signed off on an image and you can't deliver that image, there are problems.
One of the cool things about that toggle, and the Migrate Images command is that it allows you to choose to either have Aperture update non-processed images only, or processed-images only (on a per image or per project basis) and to make new versions or not. This allows you to create a side-by-side comparison when a new processing engine comes out, to compare the results.
As opposed to the model in LR/Bridge/CS3 whereby the converter is tweaked occasionally and you have no way of knowing what rev it was.