cwebp loses alpha channel during conversion

[GoogleCodeExporter]

What steps will reproduce the problem?
1. run "C:\Program Files\libwebp-0.2.1-windows-x64\cwebp.exe" -lossless 
mcFingerLightFr01_1.png -o mcFingerLightFr01_1_test.webp
or even without -lossless flag
2. open mcFingerLightFr01_1_test.webp in chrome

What is the expected output? What do you see instead?
I must see white polygon without black filling inside. But I see black filling 
inside. Source png does not have such filling

What version of the product are you using? On what operating system?
I'm using libwebp-0.2.1 windows 7 x64.

Please provide any additional information below.

Original issue reported on code.google.com by SergeySo...@gmail.com on 28 Jan 2013 at 11:29

Attachments:

• mcFingerLightFr01_1.png
• mcFingerLightFr01_1_test.webp

[GoogleCodeExporter]

I can reproduce this, note this works when cwebp uses libpng.
It likely has to do with the fact that the image is palleted, so a workaround 
would be to increase the source image's bitdepth with ImageMagick, irfanview, 
etc.

Original comment by jz...@google.com on 28 Jan 2013 at 9:05

• Changed title: cwebp loses alpha channel during conversion
• Changed state: Accepted
• Added labels: OpSys-Windows

[GoogleCodeExporter]

The following change should address the issue:
  https://gerrit.chromium.org/gerrit/#/c/42687/

Original comment by jz...@google.com on 6 Feb 2013 at 2:53

• Changed state: Started

[GoogleCodeExporter]

This has been merged.

3615295 Merge "wicdec: add alpha support for paletted formats"
c9f1649 wicdec: add alpha support for paletted formats

Original comment by jz...@google.com on 7 Feb 2013 at 8:10

• Changed state: Fixed