[magick-users] Selection from image

[Fred Weinhaus]

I am still a bit unclear about what you are trying to do.

It appears that you want to use a mask generated from a grayscale 
image. If that is the case, then you want to threshold the grayscale 
image to make it binary and then apply it to another image to select 
parts of that other image. If that is the case, then you need to use 
-threshold to make the grayscale image into binary form, then use 
-compose multiply -composite to apply it to another image.

You can also do the composite with a grayscale image if you want the 
underlying image to be seen at different intensities. The grayscale 
image then acts as a transparency mask.

See:

http://www.imagemagick.org/Usage/compose/

and

http://www.imagemagick.org/Usage/channels/


Hope that helps. If this is not what you need, then I would need a 
better explanation with examples of the the steps you want to perform.

Fred



>The grayscale image serves as a mask; in a bitmap editor, the selected
>image would
>look something like this:
>
>http://home.arcor.de/ccyrny/downloads/selection_from_mask.png
>
>Claus