[Dd_LynCh]

Alttaki şekilde yapınca oldu. Teşekkürler yardımınız için.

<%@ Page Language="C#" %>
<%@ Import Namespace="System.Drawing"%>
<%@ Import Namespace="System.IO"%>

<script runat="server">
    void Page_Load(){
        int yeniW = Convert.ToInt16(Request.QueryString["gen"]);
        int yeniH = Convert.ToInt16(Request.QueryString["yuk"]);

        string adres = Convert.ToString(Request.QueryString["adres"]);          

        Response.ContentType="image/jpg";
        string URI = server.MapPath("images/resim/"+adres);

        using (Bitmap uploadedimage = new Bitmap(URI))
	{
	decimal genislik = uploadedimage.Width;
	decimal yukseklik = uploadedimage.Height;
	         
	decimal gen_oran = (decimal) genislik / yeniW;
	decimal yuk_oran = (decimal)yukseklik / yeniH;
	        
	int olacak_gen, olacak_yuk;  

	if (gen_oran > yuk_oran)
	{
	olacak_gen = (int)(genislik / yuk_oran);
	olacak_yuk = yeniH;
	}
	else {
	olacak_gen = yeniW;
	olacak_yuk = (int)(yukseklik / gen_oran);
	}
	System.IO.Stream wClient = new System.Net.WebClient().OpenRead(URI);
	System.Drawing.Bitmap DestImage = new System.Drawing.Bitmap(uploadedimage.Width, uploadedimage.Height, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
	System.Drawing.Graphics.FromImage(DestImage).DrawImage(System.Drawing.image.FromStream(wClient), new System.Drawing.Rectangle(0, 0, uploadedimage.Width, uploadedimage.Height), new System.Drawing.Rectangle(0, 0, uploadedimage.Width, uploadedimage.Height), System.Drawing.GraphicsUnit.Pixel);
	using (System.Drawing.Bitmap imgOutput = new System.Drawing.Bitmap(DestImage, olacak_gen, olacak_yuk))
		{
		Graphics myresizer;
		myresizer = Graphics.FromImage(imgOutput);
		myresizer.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
		myresizer.DrawImage(DestImage, 0, 0, olacak_gen, olacak_yuk);

		imgOutput.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
		imgOutput.Dispose();
		wClient.Close();
		wClient.Dispose();
		}
	}
    }
</script>