I have installed acrobat pro 8 and I found that windows Explorer can show the first page of a pdf file when in 'Thumbnail' mode viewe. However, Opus9 cannot get it. Does Opus9 have this function? If can, how to make it?
Yes, search for 'image extraction' in the Prefs filter to find the option.
Make sure that "Use Shell Image Extraction" is turned on in Preferences - Lister Display Modes - Thumbnails Mode.
Also make sure that the PDFs you are viewing have embedded thumbnails by checking that Explorer shows thumbnails for them. Some PDF files are saved without thumbnail support and won't get thumbnails in Explorer or Opus.
Thanks for above help. With your guide, I can see thumbnail of PDF file.