<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW --- - pdftoppm doesn't render eci_altona-test-suite-v2_technical2_x4.pdf correctly" href="https://bugs.freedesktop.org/show_bug.cgi?id=68986#c1">Comment # 1</a> on <a class="bz_bug_link bz_status_NEW " title="NEW --- - pdftoppm doesn't render eci_altona-test-suite-v2_technical2_x4.pdf correctly" href="https://bugs.freedesktop.org/show_bug.cgi?id=68986">bug 68986</a> from <a class="email" href="mailto:Thomas.Freitag@alfa.de" title="Thomas Freitag <Thomas.Freitag@alfa.de>"> Thomas Freitag</a> <pre>I found the reason for the regression in test "C" (patch "C" in altona notation): The transparency group with knockout has two subgroups with blend mode multiply, the first one draws "TEXT TO", the second one draws "KNOCK OUT". The blend mode multiply says that we have to multiply the current color with the backdrop colour, and my implementation of knockout in <a class="bz_bug_link bz_status_RESOLVED bz_closed" title="RESOLVED FIXED - Poppler does not correctly handle knockout groups" href="show_bug.cgi?id=12185">bug 12185</a> multiplies in case of "KNOCK OUT" the blue current color with the darkened blue of "TEXT TO" where it overlaps, but the enclosing knockout transparency group forces that the "TEXT TO" has to be removed first where it overlaps and the current color has to be multiplied with the former pink background color again. After days of working and thinking about it I find now a solution, it was really complicate to solve it. BTW, also the cairo backend has big problems with it: it ignores the blend mode completely and in the overlapping region the resulting color becomes white. But I myself can only give additional hints, I'm not able to solve it in the cairo backend. The patch I'll upload in a few minutes will unfortunately only solve the knockout problem, all the other tests in the altona PDF still fails :-(</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the assignee for the bug.</li> </ul> </body> </html>