Bug #34992 [Fbk->NoF]: imageconvolution does not respect alpha

Edit report at https://bugs.php.net/bug.php?id=34992&edit=1 ID: 34992 Updated by: php-bugs@lists.php.net Reported by: jaanus at underwerks dot com Summary: imageconvolution does not respect alpha -Status: Feedback +Status: No Feedback Type: Bug Package: GD related Operating System: Linux 2.6.13 PHP Version: 6CVS-2005-10-26 (snap) Assigned To: pajoye Private report: N New Comment: No feedback was provided. The bug is being suspended because we assume that you are no longer experiencing the problem. If this is not the case and you are able to provide the information that was requested earlier, please do so and change the status of the bug back to "Re-Opened". Thank you. Previous Comments: ------------------------------------------------------------------------ [2015-05-06 22:57:36] cmb@php.net Just as jcolby said: using imagesavealpha() to save the alpha channel should be sufficient. ------------------------------------------------------------------------ [2009-03-26 17:52:30] jcolby at remove dot this dot acsol dot net The fix to this: In reference functions I manged to pinpoint a duplicate problem and solution, the destination resource image internal to the imageconvolution function needs to have the imagesavealpha flag set to true or equivalent after creation. Thats all this needs to be resolved. imagesavealpha($resource, true); ------------------------------------------------------------------------ [2007-10-30 07:50:19] michael dot buckley at ozemail dot coml dot au I am trying to make slightly blurred drop shadows for some text, but since I then need to layer it over the top of another image it needs to keep the alpha layer. Right now I am using a color to alpha function to undo this effect, but it is slow. Any one working on this? ------------------------------------------------------------------------ [2007-08-06 10:01:48] pajoye@php.net By the way, I suppose it is a typo but you are using the jpeg functions to load and save PNG. It is not going to work (and jpeg has no alpha support). "This bug still occurs with 5.2.2 which is fairly new." What make you think that anything has changed regarding this behavior? In the meantime, I figured out the source of the problem. Feedback > open. ------------------------------------------------------------------------ [2007-08-06 09:32:34] ghosh at q-one dot com This bug still occurs with 5.2.2 which is fairly new. Can't test 5.2.3 right now but it doesnt mention anything about imageconvolution in the changelog so I believe this is still unfixed. The original post about "background color" is a little bit misleading. To put it more simply: Any alpha channel information simply gets destroyed when using imageconvolution. An example image isnt really necessary because it happens with ANY png with alpha channel. I can provide one on request if absolutely necessary though. Use cases? For instance I have a dynamically generated price tag here as alpha png. I rotate it with imagerotate. Rotation makes it somewhat blurry. So afterwards I try sharpening it with imageconvolution. There you go: Alpha channel info goes down the drain... ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=34992 -- Edit this bug report at https://bugs.php.net/bug.php?id=34992&edit=1