Thanks for the info (especially the other plugins - I will try them)
Regarding PolaDSR:
1. I used <
http://legroom.net/software/uniextract> (which does not generate subfolders like WinPack) to extract "data1.cab", and I installed the tool in some virtual XP and copied the files, and now I also tried WinPack - result is that I have the right files. (But I don't know what "data2.cab" may be good for - UniExtract can't open the file because there is no data2.hdr, and WinPack extracts exactly the same files as from "data1.cab", or may be it does not really extract "data2.cab"!?).
2. I can correct my photos by running the stand-alone PolaDSR.exe - but it's awkward and quality of stored image is low, even if I select "High, largest file"

.
3. I copied all the files to "C:\Program Files\Common Files\Plug-Ins\PDSR", and added this dir to the system PATH (to make sure that the dll will be found under all circumstances ...), and added the dir to XnView "Tools » Options... » System integration » Adobe Plugins" (and rebooted Windows to make sure that PATH changes are known in whole system), but it's the same as before: The PolaDSR dialog is displayed, the sliders and check boxes etc. can be used, but most important button "Correct", which should do the correction and return to photoshop resp. XnView in this case, does nothing - PolaDSR dialog remains opened, picture in XnView does not change.
4. I then uninstalled XnView on my Win7-64 system, and reinstalled " XnView-win-small_2011-11-18_v1.98.5.exe", added "C:\Program Files\Common Files\Plug-Ins\PDSR" - but same effect: Button "Correct" does nothing.
5. I then copied the XnView program dir with PolaDSR.8bf and ScratchRemoval.dll to a (relatively) clean virtual XP (no installation): There the PolaDSR dialog is closed after pressing "Correct", focus changes to Explorer window from which I had started "xnview.exe", and XnView hangs - must be killed with task manager.