https://bugzilla.wikimedia.org/show_bug.cgi?id=24889
--- Comment #5 from Brion Vibber <br...@wikimedia.org> 2011-09-15 22:55:29 UTC --- Created attachment 9065 --> https://bugzilla.wikimedia.org/attachment.cgi?id=9065 Sample scale-downs using ImageMagick & gimp Adding a Gaussian blur on the original image before scaling seems to work wonders for this engraving; a 10x10 blur in Gimp for 310px or a 2x2 blur for 1600px both come out looking fairly smooth. Blurring may however be relatively slow, especially on large images; it's probably not the best idea to turn it on as a default. However.... I notice I actually get very good results using ImageMagick's '-resize' mode instead of '-thumbnail'. By default -resize applies a Mitchell filter; I can also apply '-filter Gaussian' which looks not quite as sharp. The -filter option seems to be ignored by -thumbnail; or if it is applied it looks like it happens after a much more primitive resampling which'll be what gives us the heavy moire: http://www.imagemagick.org/Usage/resize/#thumbnail Of course part of the reason we use -thumbnail is probably because it's fast because it doesn't do all that filtering at full resolution. :P Being able to flip particular images into the slower, more filtered scaling may actually be useful -- I suspect a simple on/off will be sufficient. But I don't know what performance impact it'll have; very large source images with high contrast are the target group, but very large source images are the exact ones that are slow and use lots of memory to resize. :( -- Configure bugmail: https://bugzilla.wikimedia.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the assignee for the bug. You are on the CC list for the bug. _______________________________________________ Wikibugs-l mailing list Wikibugs-l@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikibugs-l
