I just ran a batch of images through the queue, which is a wonderful time saver.
I was careful to be sure to uncheck “save processing parameters etc.”
However, when I looked in my target folder, there were all the PP3 files along with my images.
Did I misunderstand something about unchecking that option ?
Thanks for reading.
No, you didn’t. Maybe the PP3 files where left from an earlier convertion. It works fine on my computer.
Thanks for confirming that.
Maybe there is a glitch in my system; it is the first time those files had been in RT.
Hey !
I would agree with @TooWaBoo,
maybe test it again in a new empty folder - en then see what happens.
Regards
This PP3 file business leads me to another question, if I move or copy an image file to another folder or even another computer, does the PP3 file automatically go along for the ride or must it be treated as a separate file ?
I assume the later is correct, but this is my first experience of a program generating separate data files.
Thanks for reading.
Unless you’re using a program that is specifically aware of the .pp3 file (I’m not sure there is such a program), then the pp3 must be treated as a second file.
If you use rt file browser to move/copy the file to another folder/computer the pp3 file will also be moved/copied
Thanks, guys.
For images that I never foresee being back in RT, I am assuming that there is no reason to keep these PP3 files.
I am still learning, but I will eventually get there, wherever there is…
Thanks for your support.
I think many folks leave them around just in case, as they’re often very small in size and usually unobtrusive.
Please send directions when you’ve figured it out - many of us are still wandering aimlessly… 
Reading this thread, the following thought occurred to me:
If one converts the camera’s raw file to a DNG and subsequently edits that file with a parametric (non-destructive) editor such as Adobe Camera Raw, LR, the editing instructions are embedded directly in the DNG file rather than creating a separate (xmp) file. This ensures that the editing instructions never become separated from the original image file. Now, since RT is a parametric editor and works well with DNG files, would it not be possible to incorporate the data contained in a pp3 file directly into the DNG file?
That would mean modifying a raw file. RT never modifies raw files.
I am sure it is technically possible to write any instruction into the raw file, but as a user I object to this. My raw files are hashed so I can detect bitrot, so I don’t want them to be written over and over again, that’ll change the hash.
Plus I can copy and rename my sidecar files so that if I want to try to edit the file again with a clean slate, I can still keep my prior attempts.
I doubt the developers want to some odd bug to corrupt people’s raw files while trying to write the header.
I am way ahead of my schooling here…, but…
Are side-car files and PP3 files the same thing; I kinda think they are not ?
Is a side-car file the edited version of the RAW file, or is it just RTs recipe of what it did to the RAW file ?
So far as preserving the original RAW file as-is, could not the original files be copied, then archived, and the copies be
the files that get any editing ?
I am full of questions; I just try to ration them out a few at a time.
Thanks everyone.
Sidecar is the generic term; pp3 is the specific implementation. There are also .xmp sidecar files.
As I understand it, the sidecar file holds metadata and processing information; I’m not aware of any programs that produce a pixel copy of the image and consider it a “sidecar” file. Wikipedia seems to support that notion. In the case of RT, the sidecar file is processing instructions and metadata, like the star rating, label color, etc.
Raw files are always preserved as it, you should just archive the raw file once; the original data that came off your camera doesn’t change. I also archive the file that has other edits to it, such as the resulting .xcf if you brought the image into gimp for further editing. And archive the print version of the tif or jpeg, provided you have the space. I have 2-4 files archived generally, the raw file itself, the xcf file from gimp, the tiff that I sent to the printer, and the jpeg for the web.
Are you sure? That would be horrifying. This answer states that Lightroom keeps its instructions in its catalogue file/database, and that it can optionally add sidecar files.
Edit: after a little more reading, it seems that Lightroom can be set to store processing instructions in DNGs. Wow. Is that the default? My wife uses Lightroom (at least up until now), so I need to check. I’m going to try to get her onto Darktable.
As @paperdigits already mentioned, PP3 files are just side-car files. By “side-car” we simply mean another file that exists along with the raw file.
Basically, the raw file is usually considered source data of the image and is not normally something folks would want to change or modify. Even to ‘embed’ processing instructions into the file.
The sidecar files usually contain all of the relevant information about the raw file from a program (stars, sorting, labels, etc…), as well as including the processing instructions for processing the raw data to achieve a certain result. This has a few benefits:
The file is usually very small in size. This makes them relatively unobtrusive from a space standpoint.
The file, as already mentioned, can be moved/renamed to ‘capture’ a result from processing. So for example, if you wanted to create a certain look with an image, and then needed to create another look for some reason, you can simply rename/move/save the first sidecar file to preserve that first result, and then start working on a new look for the same raw data. At any time it’s trivial to get back the first result by pointing to the old sidecar file (and vice-versa).
It’s fairly common for various processors to keep their processing instructions in either internal databases or external sidecar files. From a data mangement standpoint it’s handy. 
Thanks! ; I am glad I asked the question.
The answers to that question also answered other questions that I had.
@heckflosse
I am aware that RT never modifies raw files. All changes (including exif & ipct) are written only to the pp3 file. I was just musing about making it possible to incorporate the pp3 data into a DNG file.
@paperdigits
I sure wouldn’t want to make any changes that might corrupt someones raw file.
@DavidOliver
Yes, I am sure that edits performed in ACR are stored in the DNG file. I don’t use LR, so I can’t be certain.
From my point of view a DNG file is a raw file. There are cameras (Pentax for example) which can be set to save DNG as raw format. There are photographers which shoot native raw (pef, nef, cr2 or whatever), convert them to DNG, delete their native raw files and keep the dng files which then are the new raw files which we (RT) don’t want to modify.
It’s quite simple: RT does not write raw files (there’s no code in rt at all to do that for example) => rt won’t be able to modify raw files, with the exception (I don’t like) of the MoveTo function in file browser…
Ingo