ublic static Bitmap ChangeSize(this Bitmap bitmap, int height, double proportion)
        {
            if (Math.Abs(1-proportion)<double.Epsilon)
            {
                var newWidth = bitmap.Height / height * bitmap.Height;
                return bitmap.ChangeSize(newWidth,height);
            }
            var width = (int)(bitmap.Height * proportion);
            var middle = bitmap.Width / 2;
            var margin = (middle - (width /2));

            return bitmap.Clone(
                new System.Drawing.Rectangle(margin, 0, width, bitmap.Height),
                 bitmap.PixelFormat);
        }