Thumbnail has blank white space

I'm running into an issue with a thumbnail on just one particular item on my library's Omeka site.

The item is a PDF. When I upload the file to Omeka, the thumbnail image it generates is not accurate. It does show the first page of the PDF, but the page is pushed over to the right side of the thumbnail image. There is a large blank white space on the left side of the thumbnail. However, when I look at the PDF I uploaded, there is no white space: it's just a normal PDF page.

We have uploaded dozens of other PDFs to our site and have never had this problem before.

Does anyone have any thoughts on why the thumbnail is displaying this way and what I can do to fix it?

Can you show what the problem looks like, or the PDF that causes the issue?

Does it happen just with one size, or with all of square_thumbnail, thumbnail, and fullsize?

A "buggy" PDF could certainly cause problems when ImageMagick tries to figure out where the bounds of the document are, but there could also be some problem with ImageMagick or Ghostscript in general or the versions on your server specifically. It's a little hard to say in the abstract.

Hi John, thank you for your help!

I think I figured out what the issue was. The PDF was from a scan that I had cropped using Adobe Acrobat Pro. Apparently cropping a page doesn't get rid of the rest of the page; it just makes the part outside the cropped area invisible. So the thumbnail was displaying the blank white space because the first page was that large- it was just invisible on the PDF since it was cropped.

I was able to delete the cropped area on every page permanently by printing to PDF. Once I did that and uploaded the new file, the thumbnail displayed normally.