public class utility
{
    public utility()
    {
        //
        // TODO: Add constructor logic here
        //
    }
    public static void C_Thumbnails(int size, string FilePath, string ThumbPath)
    {
        // create an image object, using the filename we just retrieved
        System.Drawing.Image image = System.Drawing.Image.FromFile(FilePath);

        try
        {
            int thumbHeight, thumbWidth;
            decimal h = image.Height;
            decimal w = image.Width;
            thumbWidth = image.Width;
            thumbHeight = image.Height;

            if (image.Height > image.Width && image.Height > size)
            {
                thumbHeight = size;
                decimal tWidth = (w / h) * thumbHeight;
                thumbWidth = Convert.ToInt32(tWidth);
            }
            else
            {
                if (image.Width > size)
                {
                    thumbWidth = size;
                    decimal tHeight = (h / w) * thumbWidth;
                    thumbHeight = Convert.ToInt32(tHeight);
                }
            }
            // create the actual thumbnail image	
            System.Drawing.Image thumbnailImage;
            thumbnailImage = image.GetThumbnailImage(thumbWidth, thumbHeight, null, IntPtr.Zero);
            image.Dispose();

            // put the image into the memory stream			
            thumbnailImage.Save(ThumbPath, System.Drawing.Imaging.ImageFormat.Jpeg);
        }
        catch (Exception ex)
        {
            image.Dispose();
            throw ex;
        }
    }
}