How can I check if a rectangle is inside another rectangle Emgu C#

Question

I have a problem looking forward to people to help when i detect and face recognition using Emgu Library,before face detection i draw a rectangle on the picturebox, the purpose is i want to face detection and recognition are located inside this rectangle if the face is outside the rectangle will not detect and identification, how can I do this?Please help me. My email : giangnamnam@gmail.com,thank you very much.

Descriptions:

Step 1: Detection and recognition

Step 2: I want the result will look like this

Here's my code:

• Draw rectangle on picturebox :

   private void pictureBox1_Paint(object sender, PaintEventArgs e)
  {
     Rectangle rect = new Rectangle(90, 80, 160, 160);
      using (Pen pen = new Pen(Color.Red, 2))
      {
          e.Graphics.DrawRectangle(pen, rect);
      }
  }
  

  • Code for face detection :

    private void btn_FaceDetection_Click(object sender, EventArgs e)
    {
    
        Image<Bgr, byte>   imgOriginal = new Image<Bgr, byte>(new Bitmap(pictureBox1.Image));
        Image<Gray, Byte> grayFrame = imgOriginal.Convert<Gray, Byte>();
        Rectangle[] facesDetected = haar.DetectMultiScale(grayFrame, 1.2, 5, new Size(50, 50), Size.Empty);
    
        if (facesDetected.Length > 0)
        {
            for (int i = 0; i < facesDetected.Length; i++)
            {
                facesDetected[i].X += (int)(facesDetected[i].Height * 0.1);
                facesDetected[i].Y += (int)(facesDetected[i].Width * 0.15);
                facesDetected[i].Height -= (int)(facesDetected[i].Height * 0.2);
                facesDetected[i].Width -= (int)(facesDetected[i].Width * 0.2);
    
                // print face to view
                Image<Gray, Byte> result = grayFrame.Copy(facesDetected[i]).Convert<Gray, Byte>().Resize(150, 150, INTER.CV_INTER_CUBIC);
                result._EqualizeHist();
                picb_ViewFace.Image = result.ToBitmap();
    
                // draw rectangle for face
                imgOriginal.Draw(facesDetected[i], new Bgr(Color.Green), 2);
            }
        }
    
        pictureBox1.Image = imgOriginal.ToBitmap();
    
    }