EmguCV - Face Recognition - 'Object reference not set' exception when using training set from Microsoft Access Database

Question

I\'ve been developing a face recognition application using EmguCV (C#). I got the whole thing working okay if I store the face images (training set) in simple windows folder

Answer 1

Finally made it!! just one more day of coding helped me to got the problem solved:

public void ProcessRequest(HttpContext context)
{
    _httpContext = context;
    var imageid = context.Request.QueryString["Image"];
    if (imageid == null || imageid == "")
    {
        imageid = "1";
    }


    using (WebClient wc = new WebClient())
    {
        // Handler retrieves the image from database and load it on the stream
        using (Stream s = wc.OpenRead("http://mypageurl/Image.ashx?Image=" + imageid))
        {
            using (Bitmap bmp = new Bitmap(s))
            {
                AddFace(bmp);
            }
        }
    }

}

public void AddFace(Bitmap image)
{
    var faceImage = DetectFace(image);
    if (faceImage != null)
    {
        var stream = new MemoryStream();
        faceImage.Save(stream, ImageFormat.Bmp);
        stream.Position = 0;
        byte[] data = new byte[stream.Length];
        stream.Read(data, 0, (int)stream.Length);

        _httpContext.Response.Clear();
        _httpContext.Response.ContentType = "image/jpeg";
        _httpContext.Response.BinaryWrite(data);
    }
}

private Bitmap DetectFace(Bitmap faceImage)
{
    var image = new Image(faceImage);
    var gray = image.Convert();
    string filePath = HttpContext.Current.Server.MapPath("haarcascade_frontalface_default.xml");
    var face = new HaarCascade(filePath);
    MCvAvgComp[][] facesDetected = gray.DetectHaarCascade(face, 1.1, 10, HAAR_DETECTION_TYPE.DO_CANNY_PRUNING, new Size(20, 20));
    Image result = null;

    foreach (MCvAvgComp f in facesDetected[0])
    {
        //draw the face detected in the 0th (gray) channel with blue color
        image.Draw(f.rect, new Bgr(Color.Blue), 2);
        result = image.Copy(f.rect).Convert();
        break;
    }

    if (result != null)
    {
        result = result.Resize(200, 200, INTER.CV_INTER_CUBIC);
        return result.Bitmap;
    }


   return null;
}

public bool IsReusable
{
    get { return false; }
}