Omeka makes an icon for the pdf files I've uploaded but some of the icons are corrupted -they look like static.
Is there a way to regenerate the icon? I suppose I'd be happy with just a generic pdf icon but then How would I do that?
My guess is that the process that creates the derivative images is having a hard time reading the PDFs. Usually a background application called imagemagick will try to create a jpg from the first page of a PDF. These look like imagemagick couldn't process the front page properly, and so it did indeed produce static.
It is possible that newer versions of imagemagick will correctly produce the derivative jpg (they came out okay on my machine with imagemagick version 6.7.7-10 . That would be something to ask you server administrator or hosting company about.
As for regenerating the images, the Derivative Images plugin will do that, but of course if the problem is in imagemagick, you'll get the same results.
I installed the plug in, chose "ALL" and left the other choices blank, but it errors. Probably imagemagik so I'll ask my hosting company.
A nice add on for Derivitive Images might be to include a choice to use simple generic icons for .pdf, .doc, etc.