Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".
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A better method of adding extra masking in Alpha Compositin is to use the correct compose method.
As mask already has alpha, use it.
Code: Select all
composite Mask.rgb Alpha.rgb -compose Dst_In alpha_masked.rgb
the above finds that parts of Alpha that falls within the non-transparent areas of the overlay mask image. if you want the reverse use 'Dst_Out' instead.
see IM Examples, Alpha Composition for more details.
http://www.cit.gu.edu.au/~anthony/graph ... ose/#dstin
You do not need to extract and mathematically merge the masks.