Ozeki Camera Recorder Stat

How to implement face detection in C#

Based on the information provided by this page you will be able to implement face detection successfully with your C# camera application. As a first step, OZEKI Camera SDK has to be installed and a reference to OzekiSDK.dll has to be added to your Visual Studio project.

Detected faces in C#
Figure 1 - Detected faces

Important: you should study this article in order to find out how to setup your Windows Forms Application correctly.

Getting started

To get started it is recomended to Download and Install the latest version of Ozeki Camera SDK. After installation you can find the example code discussed in this page with full source code in the following location on your harddisk:

Download Ozeki Camera SDK: http://www.camera-sdk.com/p_13-download-camera-onvif.html
Windows forms version: C:\Users\user\Documents\Ozeki\Ozeki SDK\Examples\Camera\04_ComputerVision\12_FaceDetection

To compile this example you will need Microsoft Visual Studio installed on your computer.

Corporate use of face detection

The face detection function is a new generation application which can make your business life a lot more easier.

Face detection can be an effective help in national public environments and it speeds up the entry procedures. For example: if you wish to digitize the entry procedure of your employees you should use the face detection function of the Ozeki Camera SDK. When someone arrives, the face of the person will be analysed and detected. This way, you can use this function for security improvement.

Implement face detection in C#

Some computer vision possibilities which are supplied by the SDK require an extra ToolKit. This ToolKit is the OzekiComputerVision.dll to which a reference has to be added in the project, just like in the case of the OzekiSDK.dll. This dll is responsible for the algorithms and tools which are necessary for the CV (Computer Vision) actions.

Face detection

For detecting faces we can use the IFaceDetector object of the Ozeki Camera SDK. After an instance has been created with the help of the static ImageProcesserFactory class we can detect on frames and on video as well.

In the case of frames the output image can be created by the Process() method of the instance. In the case of videos we have to use the ImageProcesserHandler mediahandler.

ImageProcesserHandler:

This is a mediahandler from a VideoHandler class (so it is VideoReceiver and VideoSender at the same time) which means that the input can be a VideoSender (for example WebCamera) and the output can also be created for a VideoReceiver. These connections can be achieved with the help of an instance of the MediaConnector class in the SDK.

No actions are executed on the input frames they are simply forwarded by default. However, the object which implement the IImageProcesser interface (for example the IFaceDetector) can be added with the help of the AddProcesser() method. More instance can be added which implement IImageProcesser, they will run one after the other using the image which is before them in the list.

The example uses the FrameCapture mediahandler as well which examines only every fifth frame.

Global Variables

  • OzekiCamera _camera;
  • Webcamera instance, with the help of this we can get the images

  • MediaConnector _connector;
  • Using this we can connect the mediahandlers

  • CameraURLBuilderWF _myCameraUrlBuilder;
  • Make access to all avaiable cameras, which you can select from afterwards.

  • ImageProcesserHandler _imageProcesserHandler;
  • This is a Mediahandler, which runs the IImageProcesser interface (this processes the images) on the incoming video

  • IFaceDetector _cornerDetector;
  • This is an image processer interface which can detect faces, this implements the IImageProcesser interface

  • FrameCapture _frameCapture;
  • With the help of this mediahandler we can determine the frequency of processing

  • VideoViewerWF instances
  • This is a GUI tool which is responsible for displaying the video for Windows Forms applications

  • DrawingImageProvider instances
  • Mediahandler which prepares the image which is sent by the mediahandlers from the VideoSender class for the VideoViewerWF instances.

C# code example for face detection

Windows Form  

MainForm.cs

using System;
using System.Windows.Forms;
using System.Drawing;
using Ozeki.Camera;
using Ozeki.Media;
using Ozeki.Vision;

namespace FaceDetection_WF
{
    public partial class MainForm : Form
    {
        private OzekiCamera _camera;
        private MediaConnector _connector;
        private CameraURLBuilderWF _myCameraUrlBuilder;
        private ImageProcesserHandler _imageProcesserHandler;
        private IFaceDetector _faceDetector;
        private FrameCapture _frameCapture;
        private DrawingImageProvider _originalImageProvider;
        private DrawingImageProvider _processedImageProvider;

        public MainForm()
        {
            InitializeComponent();
        }

        void MainForm_Load(object sender, EventArgs e)
        {
            Init();

            SetVideoViewers();

            InitDetectorFields();
        }

        void Init()
        {
            _frameCapture = new FrameCapture();
            _frameCapture.SetInterval(5);
            _myCameraUrlBuilder = new CameraURLBuilderWF();
            _connector = new MediaConnector();
            _originalImageProvider = new DrawingImageProvider();
            _processedImageProvider = new DrawingImageProvider();

            _faceDetector = ImageProcesserFactory.CreateFaceDetector();

            _imageProcesserHandler = new ImageProcesserHandler();
            _imageProcesserHandler.AddProcesser(_faceDetector);
        }

        void SetVideoViewers()
        {
            OriginalViewer.SetImageProvider(_originalImageProvider);
            ProcessedViewer.SetImageProvider(_processedImageProvider);
        }

        void InitDetectorFields()
        {
            InvokeGuiThread(() =>
            {
                tbMinSizeWidth.Text = _faceDetector.MinSize.Width.ToString();
                tbMaxSizeWidth.Text = _faceDetector.MaxSize.Width.ToString();
                tbMinSizeHeight.Text = _faceDetector.MinSize.Height.ToString();
                tbMaxSizeHeight.Text = _faceDetector.MaxSize.Height.ToString();
            });
        }

        void ConnectCam()
        {
            _connector.Connect(_camera.VideoChannel, _originalImageProvider);
            _connector.Connect(_camera.VideoChannel, _frameCapture);
            _connector.Connect(_frameCapture, _imageProcesserHandler);
            _connector.Connect(_imageProcesserHandler, _processedImageProvider);
        }

        void Start()
        {
            OriginalViewer.Start();
            ProcessedViewer.Start();

            _frameCapture.Start();
            _camera.Start();
            _imageProcesserHandler.Start();
        }

        void InvokeGuiThread(Action action)
        {
            BeginInvoke(action);
        }

        private void button_Compose_Click(object sender, EventArgs e)
        {
            var result = _myCameraUrlBuilder.ShowDialog();

            if (result != DialogResult.OK) return;

            tb_cameraUrl.Text = _myCameraUrlBuilder.CameraURL;

            button_Connect.Enabled = true;
        }

        private void button_Connect_Click(object sender, EventArgs e)
        {
            if (_camera != null)
            {
                _camera.CameraStateChanged -= _camera_CameraStateChanged;
                _camera.Disconnect();
                _connector.Disconnect(_camera.VideoChannel, _processedImageProvider);
                _connector.Disconnect(_camera.VideoChannel, _originalImageProvider);
                _camera.Dispose();
                _camera = null;
            }

            _camera = new OzekiCamera(_myCameraUrlBuilder.CameraURL);
            _camera.CameraStateChanged += _camera_CameraStateChanged;
            button_Connect.Enabled = false;
            ConnectCam();
            Start();
        }

        private void _camera_CameraStateChanged(object sender, CameraStateEventArgs e)
        {
            InvokeGuiThread(() =>
            {
                if (e.State == CameraState.Streaming)
                    button_Disconnect.Enabled = true;

                if (e.State == CameraState.Disconnected)
                {
                    button_Connect.Enabled = true;
                    button_Disconnect.Enabled = false;
                }
            });

            InvokeGuiThread(() =>
            {
                stateLabel.Text = e.State.ToString();
            });
        }

        private void button_Disconnect_Click(object sender, EventArgs e)
        {
            if (_camera == null) return;

            _camera.Disconnect();
            _connector.Disconnect(_camera.VideoChannel, _originalImageProvider);
            _connector.Disconnect(_camera.VideoChannel, _processedImageProvider);

            _camera = null;
        }

        private void buttonSetFace_Click(object sender, EventArgs e)
        {
            InvokeGuiThread(() =>
            {
                _faceDetector.MinSize = new Size(Int32.Parse(tbMinSizeWidth.Text), Int32.Parse(tbMinSizeHeight.Text));
                _faceDetector.MaxSize = new Size(Int32.Parse(tbMaxSizeWidth.Text), Int32.Parse(tbMaxSizeHeight.Text));
            });
        }
    }
}
	

Code 1 - Face detection example in C#

Detected faces in C#
Figure 2 - Face detection GUI

GUI

MainForm.Designer.cs

namespace FaceDetection_WF
{
    partial class MainForm
    {
        private System.ComponentModel.IContainer components = null;

        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows Form Designer generated code

        private void InitializeComponent()
        {
            this.label1 = new System.Windows.Forms.Label();
            this.label2 = new System.Windows.Forms.Label();
            this.OriginalViewer = new Ozeki.Media.VideoViewerWF();
            this.ProcessedViewer = new Ozeki.Media.VideoViewerWF();
            this.groupBox5 = new System.Windows.Forms.GroupBox();
            this.stateLabel = new System.Windows.Forms.Label();
            this.label14 = new System.Windows.Forms.Label();
            this.button_Connect = new System.Windows.Forms.Button();
            this.button_Disconnect = new System.Windows.Forms.Button();
            this.tb_cameraUrl = new System.Windows.Forms.TextBox();
            this.label13 = new System.Windows.Forms.Label();
            this.button_Compose = new System.Windows.Forms.Button();
            this.groupBox3 = new System.Windows.Forms.GroupBox();
            this.tbMaxSizeHeight = new System.Windows.Forms.TextBox();
            this.label10 = new System.Windows.Forms.Label();
            this.label9 = new System.Windows.Forms.Label();
            this.tbMinSizeHeight = new System.Windows.Forms.TextBox();
            this.label8 = new System.Windows.Forms.Label();
            this.label7 = new System.Windows.Forms.Label();
            this.buttonSetFace = new System.Windows.Forms.Button();
            this.tbMaxSizeWidth = new System.Windows.Forms.TextBox();
            this.label6 = new System.Windows.Forms.Label();
            this.tbMinSizeWidth = new System.Windows.Forms.TextBox();
            this.label5 = new System.Windows.Forms.Label();
            this.groupBox5.SuspendLayout();
            this.groupBox3.SuspendLayout();
            this.SuspendLayout();
 
            this.label1.AutoSize = true;
            this.label1.Font = new System.Drawing.Font("Microsoft Sans Serif", 8.25F, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, ((byte)(238)));
            this.label1.Location = new System.Drawing.Point(7, 399);
            this.label1.Name = "label1";
            this.label1.Size = new System.Drawing.Size(87, 13);
            this.label1.TabIndex = 0;
            this.label1.Text = "Original image";

            this.label2.AutoSize = true;
            this.label2.Font = new System.Drawing.Font("Microsoft Sans Serif", 8.25F, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, ((byte)(238)));
            this.label2.Location = new System.Drawing.Point(348, 399);
            this.label2.Name = "label2";
            this.label2.Size = new System.Drawing.Size(103, 13);
            this.label2.TabIndex = 1;
            this.label2.Text = "Processed image";

            this.OriginalViewer.BackColor = System.Drawing.Color.Black;
            this.OriginalViewer.FlipMode = Ozeki.Media.FlipMode.None;
            this.OriginalViewer.FrameStretch = Ozeki.Media.FrameStretch.Uniform;
            this.OriginalViewer.FullScreenEnabled = true;
            this.OriginalViewer.Location = new System.Drawing.Point(10, 143);
            this.OriginalViewer.Name = "OriginalViewer";
            this.OriginalViewer.RotateAngle = 0;
            this.OriginalViewer.Size = new System.Drawing.Size(330, 240);
            this.OriginalViewer.TabIndex = 17;
            this.OriginalViewer.Text = "videoViewerWF1";

            this.ProcessedViewer.BackColor = System.Drawing.Color.Black;
            this.ProcessedViewer.FlipMode = Ozeki.Media.FlipMode.None;
            this.ProcessedViewer.FrameStretch = Ozeki.Media.FrameStretch.Uniform;
            this.ProcessedViewer.FullScreenEnabled = true;
            this.ProcessedViewer.Location = new System.Drawing.Point(351, 143);
            this.ProcessedViewer.Name = "ProcessedViewer";
            this.ProcessedViewer.RotateAngle = 0;
            this.ProcessedViewer.Size = new System.Drawing.Size(320, 240);
            this.ProcessedViewer.TabIndex = 18;
            this.ProcessedViewer.Text = "videoViewerWF1";

            this.groupBox5.Controls.Add(this.stateLabel);
            this.groupBox5.Controls.Add(this.label14);
            this.groupBox5.Controls.Add(this.button_Connect);
            this.groupBox5.Controls.Add(this.button_Disconnect);
            this.groupBox5.Controls.Add(this.tb_cameraUrl);
            this.groupBox5.Controls.Add(this.label13);
            this.groupBox5.Controls.Add(this.button_Compose);
            this.groupBox5.Location = new System.Drawing.Point(12, 12);
            this.groupBox5.Name = "groupBox5";
            this.groupBox5.Size = new System.Drawing.Size(328, 125);
            this.groupBox5.TabIndex = 21;
            this.groupBox5.TabStop = false;
            this.groupBox5.Text = "Connect";

            this.stateLabel.AutoSize = true;
            this.stateLabel.Location = new System.Drawing.Point(80, 72);
            this.stateLabel.Name = "stateLabel";
            this.stateLabel.Size = new System.Drawing.Size(0, 13);
            this.stateLabel.TabIndex = 24;

            this.label14.AutoSize = true;
            this.label14.Location = new System.Drawing.Point(39, 72);
            this.label14.Name = "label14";
            this.label14.Size = new System.Drawing.Size(35, 13);
            this.label14.TabIndex = 23;
            this.label14.Text = "State:";

            this.button_Connect.Enabled = false;
            this.button_Connect.Font = new System.Drawing.Font("Microsoft Sans Serif", 8.5F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(238)));
            this.button_Connect.ForeColor = System.Drawing.Color.Black;
            this.button_Connect.Location = new System.Drawing.Point(83, 39);
            this.button_Connect.Name = "button_Connect";
            this.button_Connect.Size = new System.Drawing.Size(69, 23);
            this.button_Connect.TabIndex = 18;
            this.button_Connect.Text = "Connect";
            this.button_Connect.UseVisualStyleBackColor = true;
            this.button_Connect.Click += new System.EventHandler(this.button_Connect_Click);

            this.button_Disconnect.Enabled = false;
            this.button_Disconnect.Location = new System.Drawing.Point(180, 39);
            this.button_Disconnect.Name = "button_Disconnect";
            this.button_Disconnect.Size = new System.Drawing.Size(69, 23);
            this.button_Disconnect.TabIndex = 22;
            this.button_Disconnect.Text = "Disconnect";
            this.button_Disconnect.UseVisualStyleBackColor = true;
            this.button_Disconnect.Click += new System.EventHandler(this.button_Disconnect_Click);

            this.tb_cameraUrl.Location = new System.Drawing.Point(83, 13);
            this.tb_cameraUrl.Name = "tb_cameraUrl";
            this.tb_cameraUrl.ReadOnly = true;
            this.tb_cameraUrl.Size = new System.Drawing.Size(166, 20);
            this.tb_cameraUrl.TabIndex = 21;

            this.label13.AutoSize = true;
            this.label13.Location = new System.Drawing.Point(6, 16);
            this.label13.Name = "label13";
            this.label13.Size = new System.Drawing.Size(71, 13);
            this.label13.TabIndex = 20;
            this.label13.Text = "Camera URL:";

            this.button_Compose.Location = new System.Drawing.Point(253, 11);
            this.button_Compose.Name = "button_Compose";
            this.button_Compose.Size = new System.Drawing.Size(69, 23);
            this.button_Compose.TabIndex = 19;
            this.button_Compose.Text = "Compose";
            this.button_Compose.UseVisualStyleBackColor = true;
            this.button_Compose.Click += new System.EventHandler(this.button_Compose_Click);

            this.groupBox3.Controls.Add(this.tbMaxSizeHeight);
            this.groupBox3.Controls.Add(this.label10);
            this.groupBox3.Controls.Add(this.label9);
            this.groupBox3.Controls.Add(this.tbMinSizeHeight);
            this.groupBox3.Controls.Add(this.label8);
            this.groupBox3.Controls.Add(this.label7);
            this.groupBox3.Controls.Add(this.buttonSetFace);
            this.groupBox3.Controls.Add(this.tbMaxSizeWidth);
            this.groupBox3.Controls.Add(this.label6);
            this.groupBox3.Controls.Add(this.tbMinSizeWidth);
            this.groupBox3.Controls.Add(this.label5);
            this.groupBox3.Location = new System.Drawing.Point(351, 12);
            this.groupBox3.Name = "groupBox3";
            this.groupBox3.Size = new System.Drawing.Size(320, 125);
            this.groupBox3.TabIndex = 22;
            this.groupBox3.TabStop = false;
            this.groupBox3.Text = "Face Detection";

            this.tbMaxSizeHeight.Location = new System.Drawing.Point(225, 59);
            this.tbMaxSizeHeight.Name = "tbMaxSizeHeight";
            this.tbMaxSizeHeight.Size = new System.Drawing.Size(50, 20);
            this.tbMaxSizeHeight.TabIndex = 10;

            this.label10.AutoSize = true;
            this.label10.Location = new System.Drawing.Point(222, 39);
            this.label10.Name = "label10";
            this.label10.Size = new System.Drawing.Size(41, 13);
            this.label10.TabIndex = 9;
            this.label10.Text = "Height:";

            this.label9.AutoSize = true;
            this.label9.Location = new System.Drawing.Point(150, 43);
            this.label9.Name = "label9";
            this.label9.Size = new System.Drawing.Size(38, 13);
            this.label9.TabIndex = 8;
            this.label9.Text = "Width:";

            this.tbMinSizeHeight.Location = new System.Drawing.Point(85, 59);
            this.tbMinSizeHeight.Name = "tbMinSizeHeight";
            this.tbMinSizeHeight.Size = new System.Drawing.Size(50, 20);
            this.tbMinSizeHeight.TabIndex = 7;

            this.label8.AutoSize = true;
            this.label8.Location = new System.Drawing.Point(82, 43);
            this.label8.Name = "label8";
            this.label8.Size = new System.Drawing.Size(41, 13);
            this.label8.TabIndex = 6;
            this.label8.Text = "Height:";

            this.label7.AutoSize = true;
            this.label7.Location = new System.Drawing.Point(10, 44);
            this.label7.Name = "label7";
            this.label7.Size = new System.Drawing.Size(38, 13);
            this.label7.TabIndex = 5;
            this.label7.Text = "Width:";
 
            this.buttonSetFace.Location = new System.Drawing.Point(234, 88);
            this.buttonSetFace.Name = "buttonSetFace";
            this.buttonSetFace.Size = new System.Drawing.Size(75, 23);
            this.buttonSetFace.TabIndex = 4;
            this.buttonSetFace.Text = "Set";
            this.buttonSetFace.UseVisualStyleBackColor = true;
            this.buttonSetFace.Click += new System.EventHandler(this.buttonSetFace_Click);

            this.tbMaxSizeWidth.Location = new System.Drawing.Point(153, 59);
            this.tbMaxSizeWidth.Name = "tbMaxSizeWidth";
            this.tbMaxSizeWidth.Size = new System.Drawing.Size(50, 20);
            this.tbMaxSizeWidth.TabIndex = 3;

            this.label6.AutoSize = true;
            this.label6.Location = new System.Drawing.Point(150, 16);
            this.label6.Name = "label6";
            this.label6.Size = new System.Drawing.Size(77, 13);
            this.label6.TabIndex = 2;
            this.label6.Text = "Maximum Size:";

            this.tbMinSizeWidth.Location = new System.Drawing.Point(10, 59);
            this.tbMinSizeWidth.Name = "tbMinSizeWidth";
            this.tbMinSizeWidth.Size = new System.Drawing.Size(50, 20);
            this.tbMinSizeWidth.TabIndex = 1;

            this.label5.AutoSize = true;
            this.label5.Location = new System.Drawing.Point(7, 20);
            this.label5.Name = "label5";
            this.label5.Size = new System.Drawing.Size(74, 13);
            this.label5.TabIndex = 0;
            this.label5.Text = "Minimum Size:";

            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(687, 421);
            this.Controls.Add(this.groupBox3);
            this.Controls.Add(this.groupBox5);
            this.Controls.Add(this.ProcessedViewer);
            this.Controls.Add(this.OriginalViewer);
            this.Controls.Add(this.label2);
            this.Controls.Add(this.label1);
            this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle;
            this.MaximizeBox = false;
            this.Name = "MainForm";
            this.Text = "Face Detection";
            this.Load += new System.EventHandler(this.MainForm_Load);
            this.groupBox5.ResumeLayout(false);
            this.groupBox5.PerformLayout();
            this.groupBox3.ResumeLayout(false);
            this.groupBox3.PerformLayout();
            this.ResumeLayout(false);
            this.PerformLayout();
        }

        #endregion

        private System.Windows.Forms.Label label1;
        private System.Windows.Forms.Label label2;
        private Ozeki.Media.VideoViewerWF OriginalViewer;
        private Ozeki.Media.VideoViewerWF ProcessedViewer;
        private System.Windows.Forms.GroupBox groupBox5;
        private System.Windows.Forms.Button button_Connect;
        private System.Windows.Forms.Button button_Disconnect;
        private System.Windows.Forms.TextBox tb_cameraUrl;
        private System.Windows.Forms.Label label13;
        private System.Windows.Forms.Button button_Compose;
        private System.Windows.Forms.Label stateLabel;
        private System.Windows.Forms.Label label14;
        private System.Windows.Forms.GroupBox groupBox3;
        private System.Windows.Forms.TextBox tbMaxSizeHeight;
        private System.Windows.Forms.Label label10;
        private System.Windows.Forms.Label label9;
        private System.Windows.Forms.TextBox tbMinSizeHeight;
        private System.Windows.Forms.Label label8;
        private System.Windows.Forms.Label label7;
        private System.Windows.Forms.Button buttonSetFace;
        private System.Windows.Forms.TextBox tbMaxSizeWidth;
        private System.Windows.Forms.Label label6;
        private System.Windows.Forms.TextBox tbMinSizeWidth;
        private System.Windows.Forms.Label label5;
    }
}
	

Code 2 - GUI example in C#

Conclusion

With the help of this lecture you can successfully implement face detection with your C# camera application using the Ozeki Camera SDK. After examining this article you will have the needed information to be able to benefit from the face detection function on different fields of analytics.

Related pages

FAQ

Below you can find the answers for the most frequently asked questions related to this topic:

  1. I have not managed to build the solution. How to solve it?

    • Please set the Target framework property of the project to .NET 4.0.
    • You should add the OzekiSDK.dll to the references of the solution.
    • Please import the missing classes.
  2. What are the hardware requirements?

    • 1 GHz or faster processor
    • 1GB RAM (32-bit) || 2GB RAM (64-bit)
  3. Which OS are supported? Does it work with Windows 8?

    Yes,the SDK works with Windows 8. The following Operating Systems are supported:.

    • Microsoft Windows XP
    • Microsoft Windows Vista
    • Microsoft Windows 7
    • Microsoft Windows 8
    • Microsoft Windows 10
    • Microsoft Windows Server 2008
    • Microsoft Windows Server 2003