When I print PDF’s Sumatra 3.2 prints them light on the page and that same document when opened with Adobe Reader prints just fine to my printer. Any ideas?
More likely is that Acrobat is printing them darker, than they should be, but that’s my biased opinion without seeing a sample.
The cause is usually thin black lines are printed in a percentage of grey-tone by SumatraPDF whilst Acrobat may reinforce them to be much more monochrome.
I would expect that 0% grey is the same no matter which app
So printed the same one pixel wide line, from Acrobat, Firefox and SumatraPDF and scanned it in greyscale to prove there was no tonal difference apart from my poor scanner resolution. Its not proof simply a guide that when all things are equal the result will naturally be equal.
The topic as to why SumatraPDF is closer to “reality” is covered in https://github.com/sumatrapdfreader/sumatrapdf/issues/1732
But if you need thin lines forced blacker then simply print in monochrome