fake: fix a crash for not square images.
fake: fix a crash for not square images.

AnilRamachandran/aravis,AravisProject/aravis,AravisProject/aravis,lu-zero/aravis,AravisProject/aravis,AnilRamachandran/aravis,lu-zero/aravis,AnilRamachandran/aravis,lu-zero/aravis,AravisProject/aravis,AnilRamachandran/aravis,lu-zero/aravis,AnilRamachandran/aravis,AravisProject/aravis,lu-zero/aravis