[magick-users] Montage, Resize & Point filter

[Seth Price]

I'm trying to join two images and resize them while keeping the color  
properties of the original images. Namely, keep the background  
transparent, and the colors a limited palette. (Because I'm  
upsampling, the output should look pixelated.) But it's not and I'm  
not sure what I'm doing wrong. Here is the command I'm using:

montage -mode Concatenate -background "None" -resize 10800 -filter  
"Point" -tile 2x2 l1abaca_w.png l1abaca_e.png 2km.png

How can I maintain the colors from the input images? I can provide  
the input images on request.
Thanks,
Seth