Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".
I think it's probably the font file because if I use another font file, it works. Does anyone know what could be going on here with this font file and how I could fix it?
ImageMagick computes the label size based on the font metrics returned by the Freetype delegate library which in turn gets them from the font file itself. Its possible the font file has improper font metrics or that Freetype is not returning correct metrics.
Remember this problem is NOT a bug in IM, but caused by the interaction of the the font library IM uses, and the settings within the font itself, usually on purpose by the font designer. IM just uses the results as they are programmed in the font, which does not always produce what the user intended. Caution is thus advised with unusual fonts.
Solution as give previously.
Use a better font, or get that font fixed
Annotate the font on a larger canvas that you provide.