[Magick-bugs] A grid appears when resizing. It wasn't invited.

[Seth Price]

I've already sent this to the user list, and got one person to  
confirm the problem. When I run the following commands, a black grid  
appears on the resulting output.

convert -filter "Box" -resize 5400 inf_mor_w.png inf_mor_e.png  
+append  2km.png

montage -mode Concatenate -filter "Point" -resize 5400 inf_mor_w.png  
inf_mor_e.png 2km.png

I have the quantum size set to 8, this problem doesn't seem to occur  
when you have the quantum size set to 16. I don't think this grid  
appears for every image input, and I don't know what's special about  
my input images, so I've put them online here (warning, large images):

http://leopold.sage.wisc.edu/testing/inf_mor_e.png
http://leopold.sage.wisc.edu/testing/inf_mor_w.png

I've placed the output here:
http://leopold.sage.wisc.edu/testing/2km.png

A cropped version is here:
http://leopold.sage.wisc.edu/testing/2km_crp.png

I'm running the latest stable version of IM on a Mac. (problem also  
occurs on the previous version of IM that I was running from a few  
months ago, but I don't remember which version that was.)
Thanks,
Seth