title: Getting error:'Image<Gray, byte>' does not contain a definition for 'DetectHaarCascade' and no accessible extension method 'DetectHaarCascade'
body: <p>I'm a doing a project on face detection using EmguCV in C#.My goal is to detect faces from a webcam. Meanwhile I am getting some errors.</p>
  
  <p>I included all EmguCV dependencies and OpenCV dependencies.</p>
  
  <pre><code>using System;
  using System.Collections.Generic;
  using System.ComponentModel;
  using System.Data;
  using System.Drawing;
  using System.Linq;
  using System.Text;
  using System.Threading.Tasks;
  using System.Windows.Forms;
  using Emgu.CV;
  using Emgu.Util;
  using Emgu.CV.Structure;
  using Emgu.CV.CvEnum;
  
  namespace demo
  {
      public partial class Form1 : Form
      {
          private VideoCapture cap;
          private CascadeClassifier haar;
          public Form1()
          {
              InitializeComponent();
          }
  
          private void Form1_Load(object sender, EventArgs e)
          {
              // passing 0 gets zeroth webcam
              cap = new VideoCapture(0);
              // adjust path to find your xml
              haar = new CascadeClassifier("haarcascade_frontalface_alt2.xml");
          }
  
          private void timer1_Tick(object sender, EventArgs e)
          {
              using (Image&lt;Bgr, byte&gt; nextFrame = cap.QueryFrame().ToImage&lt;Bgr, Byte&gt;())
              {
                  if (nextFrame != null)
                  {
                      // there's only one channel (greyscale), hence the zero index
                      //var faces = nextFrame.DetectHaarCascade(haar)[0];
                      Image&lt;Gray, byte&gt; grayframe = nextFrame.Convert&lt;Gray, byte&gt;();
                      var faces =
                              grayframe.DetectHaarCascade(haar, 1.4, 4,HAAR_DETECTION_TYPE.DO_CANNY_PRUNING,new Size(nextFrame.Width / 8, nextFrame.Height / 8))[0];
                      foreach (var face in faces)
                      {
                          nextFrame.Draw(face.rect, new Bgr(0, double.MaxValue, 0), 3);
                      }
                      pictureBox1.Image = nextFrame.ToBitmap();
                  }
              }
          }
      }
  }
  </code></pre>
  
  <p>I tried replacing <code>DetectHaarcascade</code> with <code>Detectmultiscale</code>.</p>
  
  <blockquote>
    <p>ErrorCS1061:'Image' does not contain a definition for 'DetectHaarCascade' and no accessible extension method 'DetectHaarCascade' accepting a first argument of type 'Image' could be found (are you missing a using directive or an assembly reference?)</p>
    
    <p>ErrorCS0103:The name 'HAAR_DETECTION_TYPE' does not exist in the current context</p>
    
    <p>ErrorCS1579:foreach statement cannot operate on variables of type '?' because '?' does not contain a public instance definition for 'GetEnumerator'</p>
  </blockquote>