watermarking in Tiff

Question

 i am tring add a watermark on my file. but i am  getting error 'A Graphics object cannot be created from an image that has an indexed pixel format'

Here is my code . please give  a  solution for this  

 

 

 

string text = DateTime.Now.ToString("yyyy/MM/dd HH:mm:ss");

string fileName = @"C: \Users\ENGAPP73\Desktop\t4.tiff";

string watermarkText = "2914 View: " + text;

Stream stream = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read);

System.Drawing.Image image = System.Drawing.Image.FromStream(stream);

using (Graphics grp = Graphics.FromImage(image))

{

Brush brush = new SolidBrush(Color.Red);

Font font = new Font("Arial", 30.0f, FontStyle.Bold, GraphicsUnit.Pixel);

SizeF textSize = grp.MeasureString(watermarkText, font);

Point position = new Point((image.Width - ((int)textSize.Width + 10)), (image.Height - ((int)textSize.Height + 10)));

grp.DrawString(watermarkText, font, brush, position);

stream.Dispose();

File.Delete(fileName);

image.Save(fileName);