Take screenshot of a portion of screen using C#

Rectangle rect = new Rectangle(0, 0, 100, 100);
Bitmap bmp = new Bitmap(rect.Width, rect.Height, PixelFormat.Format32bppArgb);
Graphics g = Graphics.FromImage(bmp);
g.CopyFromScreen(rect.Left, rect.Top, 0, 0, bmp.Size, CopyPixelOperation.SourceCopy);
bmp.Save(fileName, ImageFormat.Jpeg);

References
https://stackoverflow.com/questions/3306600/c-how-to-take-a-screenshot-of-a-portion-of-screen