"C:\Program Files\gs\gs9.05\bin\gxps-9.06-win32.exe" -sDEVICE=png16m -r400 "pages=7.SPL"
The call stack that I got by building your source code in Visual Studio and reproducing the crash there was
> gxps.exe!send_pdf14trans(gs_imager_state_s * pis, gx_device_s * dev, gx_device_s * * pcdev, gs_pdf14trans_params_s * pparams, gs_memory_s * mem) Line 5727 + 0x19 bytes C
gxps.exe!gs_state_update_pdf14trans(gs_state_s * pgs, gs_pdf14trans_params_s * pparams) Line 210 + 0x1c bytes C
gxps.exe!gs_begin_transparency_mask(gs_state_s * pgs, const gs_transparency_mask_params_s * ptmp, const gs_rect_s * pbbox, int mask_is_image) Line 632 + 0x10 bytes C
gxps.exe!xps_paint_image_brush(xps_context_s * ctx, char * base_uri, xps_resource_s * dict, xps_item_s * root, void * vimage) Line 302 + 0x1c bytes C
gxps.exe!xps_parse_tiling_brush(xps_context_s * ctx, char * base_uri, xps_resource_s * dict, xps_item_s * root, int (xps_context_s *, char *, xps_resource_s *, xps_item_s *, void *)* func, void * user) Line 400 + 0x17 bytes C
gxps.exe!xps_parse_image_brush(xps_context_s * ctx, char * base_uri, xps_resource_s * dict, xps_item_s * root) Line 432 + 0x1e bytes C
gxps.exe!xps_parse_brush(xps_context_s * ctx, char * base_uri, xps_resource_s * dict, xps_item_s * node) Line 28 + 0x15 bytes C
gxps.exe!xps_parse_path(xps_context_s * ctx, char * base_uri, xps_resource_s * dict, xps_item_s * root) Line 1047 + 0x18 bytes C
gxps.exe!xps_parse_element(xps_context_s * ctx, char * base_uri, xps_resource_s * dict, xps_item_s * node) Line 46 + 0x15 bytes C
gxps.exe!xps_parse_canvas(xps_context_s * ctx, char * base_uri, xps_resource_s * dict, xps_item_s * root) Line 96 + 0x15 bytes C
gxps.exe!xps_parse_element(xps_context_s * ctx, char * base_uri, xps_resource_s * dict, xps_item_s * node) Line 50 + 0x15 bytes C
gxps.exe!xps_parse_canvas(xps_context_s * ctx, char * base_uri, xps_resource_s * dict, xps_item_s * root) Line 96 + 0x15 bytes C
gxps.exe!xps_parse_element(xps_context_s * ctx, char * base_uri, xps_resource_s * dict, xps_item_s * node) Line 50 + 0x15 bytes C
gxps.exe!xps_parse_fixed_page(xps_context_s * ctx, xps_part_s * part) Line 235 + 0x1b bytes C
gxps.exe!xps_read_and_process_page_part(xps_context_s * ctx, char * name) Line 452 + 0xd bytes C
gxps.exe!xps_process_file(xps_context_s * ctx, char * filename) Line 560 + 0xf bytes C
gxps.exe!xps_imp_process_file(pl_interp_instance_s * pinstance, char * filename) Line 297 + 0xd bytes C
gxps.exe!pl_process_file(pl_interp_instance_s * instance, char * filename) Line 147 + 0x14 bytes C
gxps.exe!pl_main_aux(int argc, char * * argv, void * disp) Line 422 + 0x13 bytes C
gxps.exe!main(int argc, char * * argv) Line 419 + 0x15 bytes C
gxps.exe!__tmainCRTStartup() Line 278 + 0x19 bytes C
gxps.exe!mainCRTStartup() Line 189 C