It was more than 3 weeks since my last post, I thought to have blog post about image watermarking as last week I wanted that feature for a website requirement. Even I thought that is a big case, I could do it with couple of  lines. Here see the code of lines for that.
First of all following namespaces are required for the code.
System.Drawing
System.Drawing.Drawing2D
System.Drawing.Imaging
Code:

string Imagefile = @”E:\projects\Watermarking\112.jpg”;//image path  

 Image img = Image.FromFile(Imagefile);// Create image object  

 Graphics g = Graphics.FromImage(img); //Create graphics object 

Color WatermarkColor = Color.FromArgb(200, 84, 84, 84); //color with alpha  

Font font = new Font(“Times New Roman”, 50,FontStyle.Italic); 

Brush brush = new SolidBrush (WatermarkColor);  

string WaterMarkString = “this is sample text”; 

SizeF sz = g.MeasureString(WaterMarkString, font); 

g.DrawString(WaterMarkString, font, brush,

new Point(X, Y));// Draw image with lable.  

img.Save(“image.jpg”);// save image