Program for Optimization and Resizing of an Image

using System;
using System.Web.UI.WebControls;

using System.IO;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;

public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }

    protected void cvImageType_Validate(object sender, ServerValidateEventArgs e)
    {
        if (chkImageType(Path.GetExtension(fpImage.FileName).ToLower())) e.IsValid = true; else e.IsValid = false;
    }

    protected bool chkImageType(string fExt)
    {
        switch (fExt)
        {
            case ".jpg":
                return true;
            case ".gif":
                return true;
            case ".png":
                return true;
            case ".bmp":
                return true;
            case ".tif":
                return true;
            default:
                return false;
        }
    }

    protected void cvImageSize_Validate(object sender, ServerValidateEventArgs e)
    {
        if (fpImage.FileContent.Length <= 10485760) e.IsValid = true; else e.IsValid = false;
    }

    protected void btnResults_OnClick(object sender, EventArgs e)
    {
        if (Page.IsValid && fpImage.HasFile)
        {
            string tmpName = Guid.NewGuid().ToString();
            fpImage.SaveAs(MapPath("~/Original Images/" + tmpName + Path.GetExtension(fpImage.FileName)));
            imgOriginal.ImageUrl = "~/Original Images/" + tmpName + Path.GetExtension(fpImage.FileName);

            Bitmap original_image = new Bitmap(fpImage.FileContent);
            lblOIW.Text = original_image.Width.ToString();
            lblOIH.Text = original_image.Height.ToString();
            lblOIS.Text = fpImage.FileContent.Length.ToString();
            
            OptimizeNResize(original_image, tmpName);
            if(original_image != null) original_image.Dispose();
        }
    }

    protected void OptimizeNResize(Bitmap original_image, string tmpName)
    {
        Bitmap final_image = null;
        Graphics graphic = null;
        int reqW = Int32.Parse(txtWidth.Text);
        int reqH = Int32.Parse(txtHeight.Text);
        final_image = new Bitmap(reqW,reqH);
        graphic = Graphics.FromImage(final_image);
        graphic.FillRectangle(new SolidBrush(Color.Transparent), new Rectangle(0, 0, reqW,reqH));
        graphic.InterpolationMode = InterpolationMode.HighQualityBicubic; /* new way */
        graphic.DrawImage(original_image, 0, 0, reqW, reqH);
        if (graphic != null) graphic.Dispose();
        final_image.Save(MapPath("~/Resultant Images/" + tmpName + Path.GetExtension(fpImage.FileName)));
        imgResult.ImageUrl = "~/Resultant Images/" + tmpName + Path.GetExtension(fpImage.FileName);
        lblRIW.Text = final_image.Width.ToString();
        lblRIH.Text = final_image.Height.ToString();
        if (original_image != null) original_image.Dispose();
        if (final_image != null) final_image.Dispose();

        FileInfo nfi = new FileInfo(MapPath("~/Resultant Images/" + tmpName + Path.GetExtension(fpImage.FileName)));
        lblRIS.Text = nfi.Length.ToString();
        lnkSave1.NavigateUrl = "~/Original Images/" + tmpName + Path.GetExtension(fpImage.FileName);
        lnkSave2.NavigateUrl = "~/Resultant Images/" + tmpName + Path.GetExtension(fpImage.FileName);
    }
}