Validate File Size and Dimensions (Height and Width) of Uploaded Image using C# in ASP.Net

hi

I use below code for uploading image:

       if (fup1.HasFile && fup1.PostedFile.ContentLength< 102400)
        {
            string path = Server.MapPath("~/Image/Estate/");
            string fileName = System.IO.Path.GetFileName(fup1.PostedFile.FileName);
            if (Array.IndexOf(new string[] { ".jpg", ".png" }, System.IO.Path.GetExtension(fup1.PostedFile.FileName).ToString().ToLower()) < 0)
            {
                return;
            }
            while (System.IO.File.Exists(path + "\\" + fileName))
            {
                fileName = "1" + fileName;
            }
            fup1.PostedFile.SaveAs(path + fileName);        
            Img1.Visible = true;
            Img1.ImageUrl = GetThumbNail("~/Image/Estate/" + fileName);
            Lblimg1.Text = fileName;
            Imgdelete1.Visible = !(BtnPopup1.Visible = false);
            Img1.Visible = true;
            Img1.ImageUrl = "~/Image/Estate/" + fileName;
        }

in below line I define size of image that users can upload

if (fup2.HasFile && fup2.PostedFile.ContentLength < 102400)

now I want define that users can just upload image with below size:

700*350-->width=700px height=350px

how I can do it?

best regards

neda