Bug in Export: So, can anyone recommend a program to sign and secure a PDF file created by Print-->SaveAsPDF?

I have encountered a Bug 145315 in LO where I get artifacts when exporting a document as PDF that does not appear when I print the document. But, the document needs to be signed and secured against saving, printing, and modifications. Since I can only accomplish that within LO if I export the document, I am looking for a tool (free/cheap) which will let me take an existing PDF and sign and secure it.

Does anyone have any recommendations for such a tool on macOS Mojave?


I don’t get the lines on Export to PDF using your Calc sheet in LibreOffice, nor LO, on Windows 10 (with Skia enabled, if that’s relevant).

Looking at your PDF (Export2PDFbug-ExportAsPDF.pdf) that you exported, at 400% I cannot see lines. Maybe it is a bug in your pdf viewer?

You unticked a lot of default options in Export to PDF. Did you also tick Use reference XObjects? If your pdf viewer cannot handle the output, it will display only the bitmap image, see the bottom of the help page for PDF export.

The solution is to ensure that Use reference XObjects is unticked

1 Hour later
I have tested the various pdfs, it is an issue with some pdf viewers

  • in PDF-Xchange Editor (lines gone at 1200%), Firefox (lines almost disappear at 320% but come back at higher), LibreOffice Draw (lines gone at 1000%), & GIMP I can see lines in the output of your pdf and in mine.
  • In Adobe Reader 2021.007.20099, Nuance PDF Viewer plus, Edge Browser there are no lines.

As your spreadsheet appears to be a drawing maybe you would be better creating the image in Draw. Or using the chart tool to create a chart.

The “Print - …PDF…” feature always uses a third party virtual PDF printer software, what is not a part of the LibreOffice.
Try an another virtual PDF printer (PDF24Creator, or other)

The solution appears to be use Adobe Reader, not Preview on Mac. See When You See Thin White Lines in Your PDF Files | CreativePro Network

If the reason named in the given link (simulated transparency) is really the cause, it my help to avoid PDF/A, as this does not allow transparencies.

The artifacts seem to be associated with the cell grid. Turn off the grid under Tools>Options>Calc>View and see if that makes a difference.

Hi EarnestAl,

Thanks for your reply.

A couple of things I should have noted…

  1. I have tried viewing the document in Acrobat Reader and in PDF Expert (which usually gives the best output) and both clearly had lines at all resolutions.
  2. I had considered creating a draw document, but that would be a nightmare to maintain. My actual document is 28 columns and 89 rows, and the page size is 48" by 96". It is intended to be view-only and viewed either in a browser or in a PDF reader app. The real problem is that when viewing the document at low zoom, the lines become more prominent. When embedding a scaled version of the document into a 1/4 page graphic in writer, (yes, it is not readable!) the lines seem to dominate the graphic.

I was thinking maybe this was a Mac problem, but that you found issues in Windows answers that question.

Update: Just saw your Acrobat comment. If the document was for me, I could manage that (although I did get artifacts when I tried Reader on a Mac). But, this is a document for a course, and I have no control over how it will be viewed. Therein lies the rub. THX again!

Re: File > Digital signatures > Sign existing pdf
Thanks! I didn’t know it could do that. I’ve seen several apps which let me turn editing, printing, and saving off, so having a way to sign a doc created by printing may be the solution.

However, this mess leaves me to wonder whether if I am able to create a “clean” document where I don’t see lines in anything I view, whether it will then be line-free for everyone.

Re chart suggestion: My problem is the majority of my data is text, and often I will have to grow the row height to accommodate. Unless I am missing something, I think it would be more trouble than I am having now as far as maintainability.

Thanks again for your help!

Hi Zizi64,

My problem isn’t my print driver, as printing is always without issue. (And, I did notice that GhostScript is being used on my Mac with LO.)

The problem is only with exporting. Sorry if that wasn’t clear.

Thanks for your suggestion.

Hi Villeroy,

Yes, it is indirectly related to cell grid. Turning it off was the first thing I thought for. Unfortunately, it didn’t fix the problem. The problem is somehow related to the beginning or ending of a colored group of merged cells. I have also tried turning off cell borders and that didn’t do anything helpful either.

Hi Wanderer,

I did not have PDF/A or PDF/UA enabled.

Thanks for the suggestion.

Thanks all!

If it is to be maintained, wouldn’t using the chart tools make it easier? You would just need to alter the numbers in the range to alter the chart.

You have the possibility to export it to png, select the range to be exported, click File > Export, tick Selection give it a name and OK. In next dialogue choose resolution first, then choose physical size. As they are solid blocks of colour, a png will have smaller file size than jpg as well as being clearer

As the white lines between transparency blocks also occurs in export from Adobe Illustrator, it would appear it is probably a bug in the pdf specifications themselves.

LibreOffice Calc. File > Digital signatures > Sign existing pdf

Note that print to pdf is typically bigger and has less functionality than Export to PDF.

Also note well, Adobe Illustrator also gets these screen artefacts at times with pdf exports; they don’t affect printing.