[Resolved] possible bug -compose copy_opacity IM 6.7.6.8

[fmw42]

IM 6.7.6.8 Mac OSX Snow Leopard

Seems like -compose copy_opacity has not been working properly for a while. It even goes back at least as far as ImageMagick-6.7.4-10. It looks like it is putting the alpha channel back, but then making the opaque parts partially transparent.


convert \( logo: -transparent white -write logo_tmp1.png \) \
\( -clone 0 -alpha off -write logo_tmp2.png \) \
\( -clone 0 -alpha extract -write logo_tmp3.png \) \
-alpha off -compose copy_opacity -composite logot1.png

[magick]

Post a URL to the image as it should look so we can compare and determine where the problem lies. Thanks.

[fmw42]

Post a URL to the image as it should look so we can compare and determine where the problem lies. Thanks.

The input is just logo:

I have put write statements into each step so you can see that they are correct. logo_tmp1.png is the transparent image that is then separated into alpha off and alpha (extract) and then combined back, so that it should look just like logo_tmp1.png.

But here is that result, logo_tmp1.png

[magick]

We can reproduce the problem and will have a patch within a day or two. Thanks.

[fmw42]

This is not correct in IM 6.7.6.9 beta. It shows no transparency now and the verbose info shows no alpha channel.

[magick]

Was fixed, the fix caused a side-effect so we reverted the patch. We have a new patch that should resolve the problem.

[fmw42]

This is still not fixed in the latest 6.7.6.9 beta as of 7:25 PM PDT

[fmw42]

I downloaded and installed the 6.7.6.9 beta this morning from http://www.imagemagick.org/download/beta/ which is dated 04-May-2012 21:39 10M

This bug is still not fixed. It is still coming out opaque with no transparency.

[fmw42]

This is now fixed in the latest beta. Thanks.

[magick]

To fix this bug: viewtopic.php?f=3&t=20921 and this one, an extra option is required on the command line:

• convert \( logo: -transparent white -write logo_tmp1.png \) \
  \( -clone 0 -alpha off -write logo_tmp2.png \) \
  \( -clone 0 -alpha extract -write logo_tmp3.png \) \
  -delete 0 -alpha off -compose copy_opacity -composite logot1.png
  display logot1.png

[fmw42]

To fix this bug: viewtopic.php?f=3&t=20921 and this one, an extra option is required on the command line:

• convert \( logo: -transparent white -write logo_tmp1.png \) \
  \( -clone 0 -alpha off -write logo_tmp2.png \) \
  \( -clone 0 -alpha extract -write logo_tmp3.png \) \
  -delete 0 -alpha off -compose copy_opacity -composite logot1.png
  display logot1.png

You are right. My mistake. DOH!

Sorry for the false alarm.