[Image-SIG] Serious bug in PIL's handling of PNG images

Joao S. O. Bueno gwidion at mpc.com.br
Thu Feb 17 13:39:42 CET 2011

On Thu, Feb 17, 2011 at 4:56 AM, Oliver Tonnhofer <olt at bogosoft.com> wrote:
> Hi,
> On 14.02.2011, at 12:50, Ivan Tkatchev wrote:
>> Please see the relevant discussion and patch here:
>> http://stackoverflow.com/questions/4217869/python-pil-all-areas-of-png-with-opacity-0-have-their-opacity-set-to-1
>> This is a very serious bug that affects many upstream packages.
> It's questionable if this is a serious bug. It's more a missing feature (read alpha from paletted images).

Since the alpha in paletted PNG images is in the PNG specification,
and PIL does support alpha I am quite certain this can be named a
bug. And a severe misfeature.

>> It would be nice if a fix made its way into the official PIL release so that users would not have to suffer.
> I did some contributions to improve the PNG handling and there are already in the development trunk for 1.2. You can get a source package here: https://bitbucket.org/olt/pil-2009-raclette/get/tip.tar.bz2

I appreciate your work -- congratulations for the effort. Have you
addressesd this particular issue of palleted alpha support?


> Regards,
> Oliver
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