I've been fiddling with your tool and it's a real time saver!
However, I noticed sometimes the image dimensions are a bit off: I'm trying to export a font with the latin characters (�����...) so it's a lot more characters. The problem is that the output image is 256 x 4096, and it could easily fit a more square size (probably 1024x1024).
Is there any thing I can do to prevent your tool from going crazy like this? :)