When I upload PDF to media-browser I sometimes get
- the PDF symbol as thumbnail
- a correct thumbnail of the first page of the PDF (expected result)
- a thumbnail of the first page with inverted colors
Result 1 occurs on a different machine then Result 2 and 3 but it is the same sitepackage used.
Result 3: I thought color schema of the PDF could be a problem. But there it does not make any difference between RGB and CMYK documents. Both can get wrong colors. But there are thumbnails that have the correct color.
How can I try to get rid of Result 1 and 3 so that all thumbnails are as expected?