Generating image thumbnails in ASP.NET?

Question

What is the fastest and more reliable way of generating thumbnails in .NET? I need to get any image, compress it in JPEG and resize it.

I've seen several examples with GDI+, some non-free components and I remember WPF has some good stuff about imaging. GDI+ is pretty old and the WPF stuff maybe has no benefits on a server environment though.

This has to work in a ASP.NET MVC application that runs on full trust, and if possible, synchronously.

What would you recommend?

UPDATE:

Based on Mantorok's answer I have worked out this example, but it's still GDI+, and it crashes if I try with a large image:

public void GenerateThumbnail(String filename, Int32? desiredWidth, 
    Int32? desiredHeight, Int64 quality, Stream s)
{
    using (Image image = Image.FromFile(filename))
    {
        Int32 width=0, height=0;

        if ((!desiredHeight.HasValue && !desiredWidth.HasValue) ||
            (desiredHeight.HasValue && desiredWidth.HasValue))
            throw new ArgumentException(
                "You have to specify a desired width OR a desired height");

        if (desiredHeight.HasValue)
        {
            width = (desiredHeight.Value * image.Width) / image.Height;
            height = desiredHeight.Value;
        }
        else
        {
            height = (desiredWidth.Value * image.Height) / image.Width;
            width = desiredWidth.Value;
        }

        using (var newImage = new Bitmap(width, height))
        using (var graphics = Graphics.FromImage(newImage))
        using (EncoderParameter qualityParam = 
            new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 
                quality))
        using (EncoderParameters encoderParams = new EncoderParameters(1))
        {
            graphics.DrawImage(image, 0, 0, width, height);
            ImageCodecInfo jpegCodec = ImageCodecInfo.GetImageEncoders().
                Single(e => e.MimeType.Equals("image/jpeg", 
                    StringComparison.Ordinal));
            encoderParams.Param[0] = qualityParam;
            newImage.Save(s, jpegCodec, encoderParams);
        }
    }
}

Answer 1

This has done me fine for years:

public static void CreateThumbnail(string filename, int desiredWidth, int desiredHeight, string outFilename)
{
    using (System.Drawing.Image img = System.Drawing.Image.FromFile(filename))
    {
        float widthRatio = (float)img.Width / (float)desiredWidth;
        float heightRatio = (float)img.Height / (float)desiredHeight;
        // Resize to the greatest ratio
        float ratio = heightRatio > widthRatio ? heightRatio : widthRatio;
        int newWidth = Convert.ToInt32(Math.Floor((float)img.Width / ratio));
        int newHeight = Convert.ToInt32(Math.Floor((float)img.Height / ratio));
        using (System.Drawing.Image thumb = img.GetThumbnailImage(newWidth, newHeight, new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailImageAbortCallback), IntPtr.Zero))
        {
            thumb.Save(outFilename, System.Drawing.Imaging.ImageFormat.Jpeg);
        }
    }
}

public static bool ThumbnailImageAbortCallback()
{
    return true;
}