Last modified: 2014-10-19 22:41:15 UTC
Created attachment 5373 [details] texvc image demonstrating the problem In images produced by texvc, the vertical stroke on a superscript z isn't visible, making the z look more like the \approx symbol. Example image attached was taken from http://upload.wikimedia.org/math/9/b/e/9becb59e2f42cc312ced208fc5e4fe18.png
Presumably that's all a TeX rasterization issue... not sure what we could adjust?
Created attachment 5379 [details] math image made on test wiki with dvipng
Created attachment 5380 [details] math image made on test wiki with dvipng (correct version)
Created attachment 5381 [details] math image made on test wiki with dvips/convert It seems the issue is with dvipng. I installed a test wiki from svn and texlive 2007 via the debian packages, and made two math images (attached). One image uses dvipng 1.11. You can see I have the same problem as the wikimedia servers. The other image uses dvips/convert to make the image. It does not have the antialiasing problem. Software versions: ImageMagick 6.3.7 05/02/08 Q16 http://www.imagemagick.org dvips(k) 5.96.1 Copyright 2007 Radical Eye Software (www.radicaleye.com)
Testing suggests that disabling freetype (adding the --freetype0 option) may fix the problem with dvipng. The cost of this is that rasterized bitmap fonts will be stored on the servers.
This looks like a problem with a newer version of dvipng and/or freetype. Using (on Fedora 9): TeX, Version 3.141592 (Web2C 7.5.6) [TeXLive 2007] dvipng 1.9 freetype-2.3.8-0.1.20080729cvs.fc9.i386 and a test document containing just "$e^{8z}$", I get a fairly well rendered z. I'll upload a picture. I haven't tried it through the MediaWiki, but I doubt it would matter. You can run dvipng in max debug mode (-d -1), and you get an ascii art version for each letter, as rendered by freetype. This is how mine looks like (pretty visible : OPEN FT FONT: '/usr/share/texmf/fonts/type1/bluesky/cm/cmmi7.pfb' @182 DRAW CMD: SETC_122 FT CHAR: 'z' 122 at (40,9) tfmw 250390 LOAD FT CHAR 122 (250390) (6x4) DRAW GLYPH 122 0 68 170 119 153 0 | 0 0 34 153 17 0 | 0 68 136 0 34 0 | 34 153 119 170 68 0 | CBM, what version of freetype are you using? Do you get the bug without involving MediaWiki?
Hmm, I've tried TeXLive 2008, dvipng 1.11 statically linked to freetype 2.3.7 (binary from TL 2008), and I get the exact same grayscale image as above: OPEN FT FONT: '/tl/2008/texmf-dist/fonts/type1/bluesky/cm/cmmi7.pfb' @182 DRAW CMD: SETC_122 FT CHAR: 'z' 122 at (40,9) tfmw 250390 LOAD FT CHAR 122 (250390) (6x4) DRAW GLYPH 122 0 68 170 119 153 0 | 0 0 34 153 17 0 | 0 68 136 0 34 0 | 34 153 119 170 68 0 | So, the problem doesn't seems to be caused by dvipng 1.11 alone.
see http://math-test2.instance-proxy.wmflabs.org/wiki/15777 rendered with Math 2.0 which needs to get a review https://gerrit.wikimedia.org/r/#/c/85801/
The changes of Math 2.0 got merged. So I expect that this bug is fixed.
