mng_minimum_box  5564 coders/png.c               mng_info->clip=mng_minimum_box(fb,mng_info->frame);
mng_minimum_box  6874 coders/png.c           crop_box=mng_minimum_box(crop_box,mng_info->clip);
mng_minimum_box  6875 coders/png.c           crop_box=mng_minimum_box(crop_box,mng_info->frame);
mng_minimum_box  6876 coders/png.c           crop_box=mng_minimum_box(crop_box,mng_info->object_clip[object_id]);