Gebruiker:Pudding4brains/PNG-Bug
Van Wikipedia
In support of bugreport Bug 6205
Inhoud |
[bewerk] 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 could be.
[bewerk] Related
The "ugly with alpha channel" issue might be related to Bug 234, but the issue described in this report is not limited to Internet Explorer, in fact it has nothing to do with the browser - the issue is in the server software.
[bewerk] Examples
| The original here is a 75K, 400x655 PNG in 4 bit/pixel greyscale with alpha channel enabled on the lightest (nearest white) 'color'. Of course, the display below is the resized 'broken' version | This is what it looks like if I resize it myself. | This is the equivalent of the original, but with alpha OFF (76K, 400x655, 4bpp) |
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| The resize is 195K, 32bpp (24bpp used), alpha ON (but the alpha is now black) and ugly | This one is 28K, 300x328 4bpp, alpha ON | The resize now looks good, but has no alpha an is still 108K, 32bpp (24bpp used) where 28KB or less would do fine too |
[bewerk] Resolved?
The latest reply to bug 6205 states that the issue should be resolved as all servers are now upgraded to a new version of ImageMagick.
Looking at the pictures above I'd say it still looks the same. So either the server isn't upgraded properly or the newer version doesn't fix the problem? I'll try a few other sizes to avoid being tricked by a server side cache or proxy sending the old 200px version:
| 100px | 198px | 202px | 300px |
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This is STRANGE - only the 300px version is displayed?! But at least that one makes it clear that the uglyness issue is not resolved.
