64-bit support for image operator?

The Generic Mapping Tools (gmt.soest.hawaii.edu <http://gmt.soest.hawaii.edu/>) produce PostScript maps and we are having trouble with PS images made from truly large data grids (e.g., 129600 by 64800) which requires 64-bit addressing.  We do use 64-bit addressing but the gs-produced images show artifacts you would expect if addressing is only 32 bit.   Since the Adobe Language specification says integers are signed 32-bit integers I wonder if images with dimensions of this nature will fail to render correctly with gs? Can anyone in the know confirm if the gs engine is using 64-bit integers for such address calculations?  If not then we will need to split the image into tiles.  If it does support this large images then we may have a bug in GMT.

Paul Wessel