problem converting png with alpha to web

[tsahia]

test:
using latest webp from today (11 july 2012 download from http://git.chromium.org/gitweb/?p=webm/libwebp.git) that supports alpha in webp and png.
take a png image with alpha, convert to webp and back. check if the alpha is there

It used to work in version 6.7.6-5 but in newer version (i tested 6.7.7-7 and 6.7.8-2) i lose the alpha channel.

Thanks

[fmw42]

Perhaps you should post your version of IM, your platform, your command line and post a link to your image.

[tsahia]

sample image i used is http://www.w3.org/Graphics/PNG/alphatest.png


IM version that is working 6.7.6-5
IM Versions that are not working well 6.7.7-7 and 6.7.8-2

platform: CentOS 6.2

command line
convert alphatest.png alphatest.webp
convert alphatest.webp alphatest_converted.png

result:
i get a png with alpha channel but the image is opaque

[glennrp]

The alpha channel also gets lost when I convert the .webp to .txt

I can't verify that IM-6.7.6-5 and earlier ever preserved the alpha
channel. I tested as far back as IM-6.7.1-1.