code: protected static float safe( int x , int y , GrayF32 image ) {
  		if( x < 0 ) x = 0;
  		else if( x >= image.width ) x = image.width-1;
  		if( y < 0 ) y = 0;
  		else if( y >= image.height ) y = image.height-1;
  
  		return image.unsafe_get(x,y);
  	}
docs: Ensures pixel values are inside the image.  If output it is assigned to the nearest pixel inside the image