# verapdf PDF/A-1B validation errors

I am trying to prepare my thesis for publication and one the requirements is to generate a PDF/A-1B compatible file out of it.

I am using verapdf software to validate my final PDF file and got these three type of error:

1. An XObject dictionary shall not contain the SMask key

1. For all Type 1 font subsets referenced within a conforming file, the font descriptor dictionary shall include a CharSet string listing the character names defined in the font subset, as described in PDF Reference Table 5.18

1. A Group object with an S key with a value of Transparency shall not be included in a form XObject. A Group object with an S key with a value of Transparency shall not be included in a page dictionary

I tried to find out what is their meaning but it is not so easy for me to find a good reference. I think the main source of the problem is the set of my PNG format images.

Any useful advice will be appreciated.

• Welcome to TeX.SX! Please help us help you and add a minimal working example (MWE) that illustrates your problem. Reproducing the problem and finding out what the issue is will be much easier when we see compilable code, starting with \documentclass{...} and ending with \end{document}. – DG' Feb 5 at 19:16
• In addition to showing us how you call fonts and include graphics Certainly a .png will often have transparency, it is a primary use for that format over others. Equally a pdf from such a .png would not be a good import. So use any graphics package to remove transparency when not required from a source image before adding via the TeX file. does the 36 objects equal your PNGs including any pdf imports from similar? Your First and third errors are from that cause "prohibits the use of transparency within a conforming PDF/A-1 document." – KJO Feb 5 at 19:22
• What we are left with is only your second error THAT IS Font subsets are acceptable by PDF/A as long as the embedded font programs provide glyph definitions for all characters referenced within the file. Embedding the font programs allows any conforming reader to reproduce correctly all glyphs in the manner in which they were originally published without reference to possibly ephemeral external resources. So we need your MWE to show how you call fonts in the preamble AND a selection of real usage in the main section PLUS ALL imports that may have text (are you loading some EPS or PDF?) – KJO Feb 5 at 19:32
• Hi @KJO, Many thanks for your guidance. I removed the alpha channel of my images and the first and the third error messages are gone. – Ali Feb 5 at 21:02
• Did the number of font errors reduce from 16 if not there is still work needed to pass that test (unless the publishing house relax that requirement.) Are you using some fancy font in a section or an equation editor insert that is non conventional ? – KJO Feb 5 at 22:19