private void Image2Icon(string fileName, string targetFileName)
{
    //Creats filename with ico extention
    string newFileName = Path.ChangeExtension(targetFileName, ".ico");
    //Getting the Icon from the Filename
    using (Icon icon = Icon.ExtractAssociatedIcon(fileName))
    {
        //Creating the Icon file and Writing the content
        using (Stream stream = File.Create(newFileName))
        {
            icon.Save(stream);
        }
    }
}