Subject: | paste()/rubthrough() should adapt the source image data to the target |
Currently pasting a 3 channel image onto a 1 channel image writes the
red channel as the grey channel. This is broken.
Currently pasting a 1 channel image onto a 3 channel image writes junk
into the green and blue channels.
Currently pasting a 4 channel image onto a 3 channel image does
something, whether that something is useful or not is hard to say.
Currently pasting a 3 channel image onto a 4 channel image writes junk
as the alpha channel.
There are similar issues with rubthrough.