FWIW, I had moved away from DT for a while, using Lightzone instead (a FOSS application). It is similar to (if not quite as powerful) as DT in that it allows you to mask areas of the raw file to which you want to apply various edits.
Early this morning, I got to thinking, "why am I trying to figure out this thing with DT. Instead, why not uninstall Gimp (the application which, by default, installed DT on my computer in the first place, and re-install it.
I took great pains to insure that I could accurate search for the version of Gimp I had installed (Gimp 2.9.7-0z0-ppa-6dfe04e), and, while that version appeared in my Ubuntu Software even after I uninstalled the ap, I could not re-install via Ubuntu Software.
As an alternative, I pasted “Gimp 2.9.7-0z0-ppa-6dfe04e” into my browser and searched for the file. That file didn’t appear, but options to install Gimp 2.9.9 appeared. I installed that newer version, and the DT that came with it is not behaving as I would expect.
If I open a file with Irfanview, I can navigate to that file (from Gimp or DT), to also open it, and my starting point is very similar to what Irfanview returns as a preview.
If the RAW preview file (ok, a JPEG camera file from Irfanview or some other viewer) seems perfect, I can accept that result in DT and just export it to whatever output format I choose. If I want to make corrections, I start from the camera’s interpretation of the RAW file. That is what I wanted.
While most responders to this thread seemed to understand my dilemma, some continue to insist that a RAW file imported into DT should differ greatly from the embedded JPEG representation. As I clearly mentioned in previous posts, this problem was only experienced in DT, not other applications (BTW, while most of the other applications I mentioned are proprietary, RawTherapee and Lightzone are clearly not. If they (or the proprietary aps) contained information that DT did not, then, DT needs that information (I know, I need to submit sample RAW files, which I will do in due time).
OTOH, I had experienced many a session with DT where this issue did not present itself, so felt that such “lack of information” was not the underlying issue.
For me, the bottom line is that a re-install of the software has cured the problem. I do not know if I inadvertently made some sort of global change that caused my problems, whether some auto-update might have caused it, or some other issue of which I am unaware.
The application is working to my satisfaction at this point which make me very happy. In most cases, I can process a raw file to my satisfaction without the need to use Gimp or PS at all.
I’m no spring chicken (oh, I so wish that I were), and have been poking around these photo editors for quite a while (started with Micrographx (sp??) Picture Publisher when I felt all my storage needs were met forever because my PC included 2 (TWO!) 40 mb hard drives!!).
That little ap was quite capable for its day.
I graduated to PS, then discovered GIMP, and mostly ignored Lightroom when it became available (could not see the point).
It was PS Bridge that first lured me into the LR/DT sort of applications, then, I learned LR, and that emboldened me to tackle DT, an application that I had dismissed as totally too obscure to bother learning.
My eyes have only recently been opened, and, for the moment, I regard DT as the most powerful of all the RAW processors with which I have had contact. It is, for me, the cat’s meow.
I sincerely appreciate all the replies to my question, even those with which I take some issue. Second to actually capturing photos (on film as well as in the digital format), I most enjoy working on the computer to make from those captures photos that exceed what one can achieve straight out of the camera.
Again, thank you for your replies.