I think I found the post you are referring to regarding the "destructive" TIFF processing of ACR ( http://www.luminous-landscape.com/forum/lo...php/t25437.html
) . I believe part of the problem is with the definition of "destructive".My definition of "destructive" would revolve around the question "Does the newly created file allow me to get the original pixels back if I want to?"
. If the answer is "No", then the process was destructive. If the answer is "yes", then the process was not destructive.First example using a scanned TIFF and Photoshop:
I bring the TIFF into PS with 16 bits as a background layer. I then do a variety of edits on layers
and save the newly-created image as a PSD, including my background layer. This could be considered "non-destructive" since I have the option of opening the PSD, removing all the edited layers, and getting back to my original TIFF pixels.Second example using ACR:
I bring the TIFF into ACR. I make edits, which are stored as commands
within the TIFF file. The file will change but the pixels will not. If I want to return to my original pixels, I can re-open the TIFF, remove the edits (Selecting Camera Raw Defaults from the fly-out menu should do the trick), and I am back with the original pixels. Again, non-destructive.Now there are some things to be aware of when using ACR to edit TIFFs and Jpegs:
- As I mentioned above, ACR will modify the file
even though the pixels themselves are unchanged within the file. This will cause the filesize and filedate to change. This could
also introduce the possibility of damaging the file if Adobe happened to have a bug in its software or if something happened to your PC while writing the file (like a power outage). Only you can assess if that is a big risk or a small one.
- The commands that ACR inserts into the TIFF or Jpeg will be understood only by certain Adobe products. Non-Adobe products will be able to read the file but without the edits applied by ACR (this is actually another indication that the ACR process is non-destructive to the original pixels and might even be handy under certain situations).
Regarding why Jeff left out the "doubt" in the latest version of his book, only he can answer definitively. Maybe he will if he is back now from playing with penguins. If I were to speculate, however, I suspect Jeff's logic was something like the following:
- RAW HAS
to be interpreted so RAW+recipe of some type is a given as well as the non-destructive nature of such an arrangement.
- Jpegs and TIFFs can be interpreted "as-is" and do not NEED a recipe.
- Tools like Photoshop already provide a means to do non-destructive editing of TIFFs and Jpegs using layers as I mentioned in my first example above.
- Is it really worth it to duplicate that non-destructive functionality when you don't have to? What about the file change caveats I mentioned above? (RWCRwAP CS3)
- Ah screw it. Choice is good. ACR now has some nifty and easy-to-use tricks like gradients and localized brushes. Let users decide if it's better to use ACR or PS for TIFFs and Jpegs. (RWCRwAP CS4)
Here is a link to John Nack's blog that provides some additional info:http://blogs.adobe.com/jnack/2007/02/nondestructive.html
If you take the time to read through the comments on John's blog, including his replies, you will note that Adobe's intent was to make ACR into a tool to read and edit camera-generated
files. That is why Raw, TIFF, and Jpegs are included but PSDs, for example, are not. Since in your case, the TIFFs are scanned images, not pics from a camera, that might be worth a conceptual ponder. In the end though, choice is good and make up your own mind.