Copying the channel

[Ofnuts]

Method #1:

• Drag the channel thumbnail from the source image's Channels list to the target image. This adds it as a layer in the target.
  
• Open the Channels list in the target image, and drag any of the R,G, or B channels to the main list to copy it
  
• Delete the copied layer
  

Method #2:

• Make the channel active in the source image
  
• Select>All, Edit>Copy or Ctrl-C
  
• In the target image, create a new channel, and make sure it is the active channel
  
• Edit>Paste, and don't worry that it seems to be pasted as a layer, this isn't really the case
  
• Layer>Anchor (or Ctrl-H) and it gets pasted/anchored into the target channel
  

Also, little known trick: if the active layer is a channel, File>Export doesn't export the image (ie, composition of the layers) but the channel. But to load a channel from file, you have to open the file as layers, and drag an RGB channel as in method 1#.