Garbled text when opening previously opened PDFs

anjislinky · October 6, 2023, 4:00pm

Hi, I’m new to posting on forums so feel free to ask any questions if I’ve not clarified anything.

I am a university student who uses an Acer Chromebook Spin 311 and I have been using it for over 3 years with no issue using any of the software (ChromeOS) until now.
I download powerpoints as tagged PDFs from my university portal and then annotate on them with a stylus and then save them to the hardware of my laptop as opposed to saving directly onto my google drive just for convenience. Recently (last 2 months), I noticed some of the previously saved PDFs from last year have had text replaced to special characters and no actual legible writing. I checked the information for the PDF and it says the application was “Impress” and the producer was “LibreOffice 7.3” (some other versions are 7.0), and the PDF version is 1.6. This has also happened to a PDF I had just downloaded yesterday so it’s not an older problem.
I’ve narrowed this down to what I assume is a text formatting issue, however I’ve changed nothing on my laptop since I’ve noticed this issue, apart from run scheduled OS updates. None of these updates should have affected the PDF software.
ChromeOS is also very simple and therefore I’m not sure how to alter anything specific and all the other solutions for similar problems like mine are for Windows or iOS and require the OCR changing. I’ve sent the PDFs to other people with Window laptops and software they aren’t able to change any of the text back to normal.
I never specifically downloaded LibreOffice to view these PDFs so I’m not sure if this is the right space to post this problem. I have managed to download some of the PDFs into a Google application (?) and haven’t had this problem however this could change.

Below are examples of the problems. As i am a new user i am not allowed to use more than 1 embedded image.

webmink · October 7, 2023, 4:25pm

The problem sounds like you have a file association that is opening the wrong app. Can you tell me which ChromeBook app is opening the PDF please? On my ChromeBook it tends to be Gallery or the browser. You can find out by right-clicking in Files on one of the files that’s going wrong, picking “Open with” and clicking “Change default” (don’t change it unless you are sure!)

anjislinky · October 9, 2023, 9:18am

Mine opens up by Gallery as a default and I’ve never really changed it as far as I can tell - at least not recently. I could change the default to browser but I’ve just checked and it still opens with LibreOffice 7.3.

webmink · October 9, 2023, 9:59am

Do you have LibreOffice installed on the Chromebook?

anjislinky · October 9, 2023, 10:41am

No. I have never actually installed it or even heard of it until I was looking up solutions to fix the text.

webmink · October 9, 2023, 10:57am

OK. All I can think is that the original files have been corrupted by saving the annotations. I don’t annotate on my Chromebook so I don’t have any further experience to share of that, sorry. You could try opening them with the app that annotated them, or you could try installing LibreOffice (I recommend the AppImage version as easiest to install and keep updated) and see if it can open the files (but I am not hopeful).

Wanderer · October 10, 2023, 5:39am

I don’t think this is a way to solve this, and IMHO it is also difficult. LibreOffice is no app for ChromeOS. It would run in the debian subsystem. But LibreOffice is a poor Editor for pdf-files and not at all suited to repair pdf.
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My guess is, all this is unrelated to LibreOffice. The documents downloaded from the university may be created with LibreOffice. Impress doesn’t seem unlikely as it is used for presentations. But @anjislinky could read this files and annotate, all this happened after conversion to pdf and downloading to a computer without LibreOffice. Whatever happened there is not done by LibreOffice.
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To analyze, what has happened to the pdf-files, it would be useful to have the file from university and the current result. Maybe change of pdf-readers can give an result, but without any knowledge, wich software was used to annotate “we” are mostly in the dark.
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So, if you seek help, please upload a modified pdf and the “source” without annotations here and hope somebody can make sense of the file.
Second task would be to find out the name of the software used for annotations, because “with a stylus” does not reveal anything.

anjislinky · October 11, 2023, 2:50pm

I have added the files to a google drive
“for libre office – Google Drive”. They’re labelled as:

a powerpoint for the way the document is originally added to the university website
tagged (original), which is directly downloaded and automatically converted to a PDF through the university website with no annotations
tagged (corrupt), which is the corrupt file with annotations
google, which is a PDF file i have managed to create from turning the powerpoint into a google slides presentation, then into a PDF.

The “stylus” is a Staedtler noris digital pen which I used as a replacement pen for the one that comes with the laptop. The laptop uses Wacom EMR pens to write on the screen in a similar way to an apple pencil and has palm rejection. This is the specific reason I bought it. I purchased this in mid February and I used to use a regular generic stylus with a rubber tip between then and the beginning of 2023.

In regards to the comment you made about Impress being used for presentations, the “PDF” is actually a powerpoint originally and software on the website can let you change it into different formats eg PDF, HTML, Braille. I’ve only ever used the PDF options and when they are downloaded they have the word “tagged” after the title, hence the word “tagged” in both my explanations and the files you should see.