<--div>
        <--asp:Label ID="lblError" runat="server" Width="100%">
    <--/div> 
    <--div>
        <--asp:TextBox ID="txtImageName" runat="server">  
        <--asp:Button ID="btnImage" runat="server" Text="Create Image" 
            onclick="btnImage_Click" />
    <--/div>
    <--div>
<--asp:Image ID="Image1" runat="server" Visible="false"  AlternateText=""  />
    <--/div>

protected void btnImage_Click(object sender, EventArgs e)
    {
        try
        {
            if (txtImageName.Text.Trim() == "")
                throw new Exception("Please enter text to draw image");
            CreateBitmapImage(txtImageName.Text.Trim());
        }
        catch (Exception ex)
        {
            Image1.Visible = false;
            lblError.Text = ex.Message;
            lblError.Visible = true;
        }
    }

 private void CreateBitmapImage(string sImageText)
    {
        // Creatin Bit map Object
        Bitmap objBmpImage = new Bitmap(1, 1);
        // As we don't know how much we have to set height and width to the image so declaring two integer variables
        int intWidth = 0;
        int intHeight = 0;
        // Create the Font object for the image text drawing.  
        Font objFont = new Font("Arial", 20, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Pixel);
        // Create a graphics object to measure the text's width and height. 
        Graphics objGraphics = Graphics.FromImage(objBmpImage);
        // This is where the bitmap size is determined. 
        intWidth = (int)objGraphics.MeasureString(sImageText, objFont).Width;
        intHeight = (int)objGraphics.MeasureString(sImageText, objFont).Height;
        // Create the bmpImage again with the correct size for the text and font. 
        objBmpImage = new Bitmap(objBmpImage, new Size(intWidth, intHeight));
        // Add the colors to the new bitmap. 
        objGraphics = Graphics.FromImage(objBmpImage);
        // Set Background color 
        objGraphics.Clear(Color.Black);
        objGraphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighSpeed;
        objGraphics.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias;
        // This methods draws the specified text string
        objGraphics.DrawString(sImageText, objFont, new SolidBrush(Color.FromArgb(255, 255, 240)), 0, 0);
        objGraphics.Flush();
        // Saving the Created Image in our server Folder
        objBmpImage.Save(Server.MapPath("Temp.jpg"));
        // setting the image path to the image Control
        Image1.ImageUrl = "Temp.jpg";
        // setting the height and width to the image as it varies text lenght 
        Image1.Width = intWidth;
        Image1.Height = intHeight;
        // showing image to the user
        Image1.Visible = true;
    }