Directory Opus can do so much I wonder if I can do this also: Directory B consists of a selection of dng files, let's say from 1 - 500. Directory A consists of a selection of jpegs, derived from the dng files, and carrying the same number as the corresponding dng file. There are not as many files in A as in B, because the files in A represent the images I want to keep. What I want to do is eliminate every dng file from B that does not have a jpeg file in A of the corresponding number, in other words to reduce B to precisely the same numbered dng files as the jpegs in A. Can I do this automatically via some formula, because it is taking a long time to do it manually?
Yes, you can do this fairly easily.
Make a button or hotkey which runs this command:
Select SOURCETODEST=noext DESELECTNOMATCH
Now open a dual-display lister, with the JPGs in one side and the DNGs in another. Select all the JPGs and click the button.
That will select the DNG files* which do have a corresponding JPG file. To get the ones which don't, activate the DNG side and use Edit -> Invert Selection.
(If it's something you need to do a lot, you could combine everything into a single button, even including the delete command if you wish. Shout if you need help with that.)
- As it is, it won't strictly select only *.DNG files; it will select any files in the other side which have the same base name (i.e. filename, ignoring the extension part) as the files selected in the active side. If you need to restrict it to *.DNG then that's possible, but if there will only be *.DNG files anyway then there's no need to complicate things with that.
That sounds fabulous ... Yes, I do need to do this a lot, so combining everything into a single button would be brilliant, but I would need help with that, and indeed, in making a button and \or hotkey in the first place ...
This explains how to add commands like the one in my post to your toolbars and menus: How to add buttons from this forum to your toolbars.
Since you won't have tried the command yet, I recommend trying it as-is and doing the other steps manually at first, just to make sure the process does what you need it to do. If it does then we can automate it into a single-click button. If it doesn't, it will be much easier to work out what needs to change when you've been able to observe the steps individually (especially as the fully automated version could delete some files you don't want deleted).