7d6e971b_Magick__Magick_Vector_Graphics__Description
[Method] copy-* [Description] 
Copy the specificed channel in the source image to the same channel in the destination image. If the channel specified in the source image does not exist, (which can only happen for methods, 'copy-opacity' or 'copy-black') then it is assumed that the source image is a special grayscale channel image of the values to be copied.
ImageMagick: Magick Vector Graphics
Description