Add watermark text to an image

How to use the Graphics class DrawString() method

Create a Graphics object from a bitmap. Then create a Font with a font name and size.

The StringFormat lets you position the text on the right side of the image (Far) or the left side of the image (Near).

Using the graphics object, write the text into the image.

Bitmap bitmap = (Bitmap)myImage;

using (Graphics graphics = Graphics.FromImage(bitmap))
{
  using (Font watermarkFont = new Font("Verdana", 12))
  {
    var rectImage = new Rectangle(10, myImage.Height - 25, myImage.Width - 20, 25);

    var myFormat = new StringFormat()
    {
       Alignment = posText == "right" ? StringAlignment.Far : StringAlignment.Near,
       LineAlignment = StringAlignment.Near
    };

    graphics.DrawString(watermarkText,
                        watermarkFont,
                        textColor == "white" ? Brushes.White : Brushes.Black,
                        rectImage,
                        myFormat);
  }
}

Add watermark text to an image

Use DrawString to write text to a Bitmap