Images contained in two PDFs generated by the same user are missing in Moodle's PDF annotation.
- The student uploads his documents in a repository with a "PDF Annotation" feedback type.
- The teacher accesses the online PDF annotation: the images are missing from the preview. When he download the PDF file the images appear properly in his PDF file viewer.
Further information :
- No other PDF has the same problem in the same repository.
- The problem can be reproduced on our test server (using the two original files).
- Both PDFs were generated from a Mac and the photos are .jpg taken with an iPhone.
- I can reproduce the problem with the student PDF files, but I cannot create a PDF file with the same type of problem by myself and I have no relevant information of how these images or PDF files are differents from others.
- If you save the PDF file via "Print as PDF" functionality and re-upload it, the problem no longer occurs
- I think Ghostscript is not involved because
- It is up to date
- I executed the GS conversion command line directly on the two PDF files from our server. The generated PNG files do contain the images.
- I was able to retrieve the "combined.pdf" file from the /temp/assignfeedback_editpdf/pageimages/ directory. It does not contain the images. I think the problem occurs before GS command line.
Since I can't produce problematic PDF files by myself and the student's PDF files contains sensitive information, I cannot upload it here. I am here to help or to test code if you give me specific instructions.