Invert with light green produces muddy brown colours in beta branch

[edwardhorsford]

I quite like the invert with light green option. Alas it seems to be broken in the beta branch with my test pdf. Most lines come out a muddy brown - where they display fine in the main branch.

I believe I have traced it (via Claude) to the fix in #402.

Beta branch

0px line weight	1px line weight

Main branch

0px line weight	1px line weight

I suspect this is related to the source data not being 100% black, but some shade of grey - unless over some threshold value it's not enough to get saturated?

Besides looking again at the fix in #402, I wonder about applying some kind of level/threshold filter so pixels over x% darkness are darkened even further? You'd lose shading in pdfs, but gain more contrast. I suspect that's probably a good tradeoff for patterns.

[courtneypattison]

Good catch! You're correct I was trying to fix #402 and introduced the muddy brown. I made a mental note to fix it before the next release but didn't reopen the bug. Apologies.

I wonder about applying some kind of level/threshold filter so pixels over x% darkness are darkened even further? You'd lose shading in pdfs, but gain more contrast. I suspect that's probably a good tradeoff for patterns.

That's definitely worth a try. I'm open to any changes that would get us to bright green for both PDFs and SVGs.