Legacy ImageMagick Discussions Archive

IM 6.7.6.5 Q16 Mac OSX Snow Leopard

I was under the impression that all commands (which use none or transparent) such as -fill none were fixed to promote the alpha channel automatically. Correct me if I am wrong.

Thus this should work, but does not.

convert logo: -fill none -opaque white show:


I know it can be made to work using

convert logo: -channel rgba -fill none -opaque white show:
or
convert logo: -transparent white show:

Many of the ImageMagick algorithms are channel aware and the default is RGB. You must add -channel rgba to your command line. ImageMagick version 7 removes the need to specify the channels and automatically processes the alpha channel if its available.