Last modified: 2008-07-30 21:34:51 UTC
== Bug ==
When resizing a fairly optimized (few bits per pixel) PNG for thumbnail display
in an Wikipedia article a few unpleasant things happen, especially when the
original has transparency (alpha channel) enabled:
# The image becomes very ugly.
# The resized image that will be transmitted by the server has a byte count that
is way larger than the 'big' original and up to ten times larger than it
== Related ==
'''Note:''' The 'resize' has larger byte count than original is same as: [[Bug
1218]] and [[Bug 5211]]
The "'''ugly''' with alpha channel" issue ''might'' be related to [[Bug 234]],
but the issue descriped in this report is '''not limited to Internet
Explorer''', in fact it has ''nothing'' to do with the browser at all.
== Examples ==
For example page visit:
Maybe upgrading to a newer version of ImageMagick might help. I have version 6.2.5 04/21/06 Q16 here
at home, and using the same options that MediaWiki uses (that should be "convert -coalesce -resize
200x328! -depth 8", right?), I get a nice PNG (although still many bytes).
As for the byte count, I haven't found options for ImageMagick yet that force it to retain a bit
depth of 4 bits. This might be something to request there. (Actually, using -depth 4 on the image
with alpha gives something even uglier than what was reported; without alpha is OK.)
We upgraded the existing servers to 6.2.6 Q8 a while ago, but unfortunately the
setup script wasn't changed, so new servers were installed with whatever was in
the repository, often 6.2.2 Q16. I've fixed this now, they're all running 6.2.6 Q8.
Hi Tim, looking at http://nl.wikipedia.org/wiki/Gebruiker:Pudding4brains/PNG-Bug
I would tend to conclude that the either the server is not properly upgraded
(yet?) or the new version ImageMagick doesn't solve the problem?
In addition to the 200px resize allready present I've tried to display 100px,
198px, 202px and 300px resizes (to maybe avoid my not seeing any improvement
being caused by a server side cache (??) but _only_ the 300px version is
dispalyed - the others are not ???! Confused ...
Sorry, didn't mean to mark it resolved. There's lots of problems here and the upgrade
would only affect some of them.
(In reply to comment #4)
> Sorry, didn't mean to mark it resolved. There's lots of problems here and the
> would only affect some of them.
Okay, no problem - thanks for reopening :)
(In reply to comment #0)
> The "'''ugly''' with alpha channel" issue ''might'' be related to [[Bug 234]],
> but the issue descriped in this report is '''not limited to Internet
> Explorer''', in fact it has ''nothing'' to do with the browser at all.
Going to repurpose the bug to this, the size issue is already covered elsewhere.
As far as I know no current issue remains. Please provide an example image file and description (original page linked no longer exists).