<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW --- - OTF and TTF versions of the same font render small type differently (hinting issue?)" href="https://bugs.freedesktop.org/show_bug.cgi?id=78990#c13">Comment # 13</a> on <a class="bz_bug_link bz_status_NEW " title="NEW --- - OTF and TTF versions of the same font render small type differently (hinting issue?)" href="https://bugs.freedesktop.org/show_bug.cgi?id=78990">bug 78990</a> from <a class="email" href="mailto:ce0c5679c447a438@spamherelots.com" title="Jerome <ce0c5679c447a438@spamherelots.com>"> Jerome</a> <pre>The freetype devs confirme that the stem darkening used by the adobe engine is the cause of the overly dark rendering of cff fonts I reported. See issue: <a href="https://savannah.nongnu.org/bugs/index.php?42406">https://savannah.nongnu.org/bugs/index.php?42406</a> Stem darkening is turned on by default, and assumes (As I understand it) that poppler properly handles "gamma", whatever that means in this context, which if not done has the effect of displaying very dark glyphs at small type size. The freetype library has an option for disabling stem darkening, as well as several numerical parameters for controlling it, whose defaults the FT devs plan to change in the future when stem darkening will be added to the other (ttf) engine as well. See: <a href="http://www.freetype.org/freetype2/docs/reference/ft2-cff_driver.html#FT_CFF_HINTING_XXX">http://www.freetype.org/freetype2/docs/reference/ft2-cff_driver.html#FT_CFF_HINTING_XXX</a> By turning off stem darkening in the constructor for CairoOutputDev (And also in splash hinting control, I do not know which had the effect): ``` CairoOutputDev::CairoOutputDev() { ... FT_Bool no_stem_darkening = true; FT_Property_Set( ft_lib, "cff", "no-stem-darkening", &no_stem_darkening ); ``` the issue has largely been resolved for me, there's still a slight difference perhaps, but only when comparing side to side. I've attached a screenshot which you can compare to the original I attached to the issue. I'd like to suggest that poppler turn stem darkening off by default, since it would: 1) Eliminate the problem of the dark glyphs. 2) Make ttf and ctf render in the same way (if they are mixed in a document for example). 3) Restore (roughly) the rendering behavior to what it was been before the relatively recent introduction of the adobe engine. If not, at least exposing an API for setting it by clients (Evince, okular) would enable downstream to scratch their own itch. Noting that since freetype releases are not often and this part of the library seems to be in an interim state since one kind of font supports darkening it, the other does not, it might be a while before this is resolved over there (though they were very helpful).</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the assignee for the bug.</li> </ul> </body> </html>