rb_define_method(Bitmap, "width", image_width, 0);
rb_define_method(Bitmap, "height", image_height, 0);
rb_define_method(Bitmap, "rescale", image_rescale, 2);
rb_define_method(Bitmap, "width", image_width, 0);
rb_define_method(Bitmap, "height", image_height, 0);
rb_define_method(Bitmap, "rescale", image_rescale, 2);