Remove transparency in images with C#

Remove Transparency from png's in c# or asp net c#

public void RemoveTransparency(string filename)
{
   using (System.Drawing.Bitmap src = new System.Drawing.Bitmap(filename))
   {
      using (System.Drawing.Bitmap target = new System.Drawing.Bitmap(src.Size.Width, src.Size.Height))
      {
          using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(target))
          {
             g.Clear(System.Drawing.Color.White);
             g.DrawImage(src, 0, 0);  
          }
          target.Save("Full path of file");
      }
   }
}