Text highlights lose their transparency after converting to PDFA format


We use PDFNet to convert PDF files to PDFA. When we highlight some text in the pdf files, using Adobe Acrobat, and the document is converted to PDFA, the highlight loses its transparency, and obfuscates the text. We can’t read the text any longer.

We are using PDFNet with Level1B Conformance setting.



PDFA Level 1 conformance restricts PDF’s to PDF Version 1.4, which did not support transparency.

Instead you should switch to Level 2B conformance, which supports PDF Version 1.7 (and therefore transparency).


I have a PDF file which probably falls into this category (as it’s PDFv1.4 - it was sent in from a customer) and there is some embedded highlight annotations that are opaque in PDFTron but transparent in Adobe Reader. If we remove/replace the tags with it works.

Can PDFTron be made to ignore the standard (when viewing) like Adobe does? It’s hard because we can’t control what a customer sends us but we still have humans that will miss important data if they don’t see it.
I can’t send you a copy of the document as it has private information in it.

Also, I tried saving the PDF using PDFTron (effectively PDF → PDF conversion)

new PDFDoc(filename).Save(newFilename, SDFDoc.SaveOptions.e_linearized);

which now shows PDF Version 1.7 but this still doesn’t show the transparency in PDFTron web viewer (still works in Adobe).