private static Rectangle GetCroppingRect(Rectangle rectangle)
{
if (rectangle.IsEmpty)
{
throw new ArgumentException();
}
var centerPoint = Dlib.Center(rectangle);
var maxDim = Math.Max(rectangle.Width, rectangle.Height);
var d = (int)(Math.Round(maxDim / 2.0 * 1.5)); // add +50%
return(new Rectangle(
centerPoint.X - d,
centerPoint.Y - d,
centerPoint.X + d,
centerPoint.Y + d
));
}