Often it is necessary to resize an image that has been uploaded. To do this you will need the following using classes:-

using System.Drawing;
using System.Drawing.Imaging;

Then here are some examples on functions with the resize code:-

public static string ResizeImageAndSave(int Width, int Height, string imageUrl,string destPath)
	{
 
 
        System.Drawing.Image fullSizeImg = System.Drawing.Image.FromFile(HttpContext.Current.Server.MapPath(imageUrl));
 
        double widthRatio = (double)fullSizeImg.Width / (double)Width;
        double heightRatio = (double)fullSizeImg.Height / (double)Height;
        double ratio = Math.Max(widthRatio, heightRatio);
        int newWidth = (int)(fullSizeImg.Width / ratio);
        int newHeight = (int)(fullSizeImg.Height / ratio);
 
        System.Drawing.Image.GetThumbnailImageAbort dummyCallBack = new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback);
        System.Drawing.Image thumbNailImg = fullSizeImg.GetThumbnailImage(newWidth, newHeight,dummyCallBack, IntPtr.Zero);
        DateTime MyDate = DateTime.Now;
        String MyString = MyDate.ToString("ddMMyyhhmmss") + ".png";
        thumbNailImg.Save(HttpContext.Current.Server.MapPath(destPath) + MyString, ImageFormat.Png);
        thumbNailImg.Dispose();
        return MyString;
	}
 
    public static bool ThumbnailCallback()
    {
        return false;
    }