Histogram equalization

In this lecture you will find detailed information on how to implement histogram equalization in C# with your camera application using Ozeki Camera SDK. After the introduction you will find detailed example codes for developing Windows Forms Application. The tutorial also includes images to help you to understand the using of histogram equalization. At the end of the tutorial you can find the answers for the most frequently asked questions.

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

How does it work?

In most cases this method increases the global contrast of many images, especially when the image date includes contrast values. By using this adjustment, the intensities can be better distributed on the histogram. It will result higher contrast on the areas which previously had a lower local contrast so you can see the soft outlines a lot more visible.

With Ozeki Camera SDK this can be achieved while viewing a video, even in real time.

before histogram equalization
Figure 1 - Original image

after histogram equalization
Figure 2 - Modified image with histogram equalization

Windows Form  

Windows forms version


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

namespace ImageManipulation_WF
    public partial class MainForm : Form
        private ICamera _camera;
        private DrawingImageProvider _imageProvider;
        private MediaConnector _connector;
        private ImageManipulation _manipulation;
        private OzHistogramEqualization _filter;

        public MainForm()

            _connector = new MediaConnector();
            _imageProvider = new DrawingImageProvider();
            // Create video viewer UI control

            // Bind the camera image to the UI control

            _manipulation = new ImageManipulation();

            _filter = new OzHistogramEqualization();

        private void btn_Connect_Click(object sender, EventArgs e)
            _camera = new WebCamera();

            if (_camera == null) return;

            _connector.Connect(_camera.VideoChannel, _manipulation);
            _connector.Connect(_manipulation, _imageProvider);


        private void btn_Add_Click(object sender, EventArgs e)

        private void btn_Remove_Click(object sender, EventArgs e)

Code 1 - Histogram equalization in C#



namespace ImageManipulation_WF
    partial class MainForm
        /// Required designer variable.
        private System.ComponentModel.IContainer components = null;

        /// Clean up any resources being used.
        /// true if managed resources should be disposed; otherwise, false.
        protected override void Dispose(bool disposing)
            if (disposing && (components != null))

        #region Windows Form Designer generated code

        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        private void InitializeComponent()
            this.videoViewer = new Ozeki.Media.VideoViewerWF();
            this.btn_Connect = new System.Windows.Forms.Button();
            this.btn_Remove = new System.Windows.Forms.Button();
            this.btn_Add = new System.Windows.Forms.Button();
            this.label1 = new System.Windows.Forms.Label();
            // videoViewer
            this.videoViewer.BackColor = System.Drawing.Color.Black;
            this.videoViewer.FlipMode = Ozeki.Media.FlipMode.None;
            this.videoViewer.FrameStretch = Ozeki.Media.FrameStretch.Uniform;
            this.videoViewer.FullScreenEnabled = true;
            this.videoViewer.Location = new System.Drawing.Point(12, 57);
            this.videoViewer.Name = "videoViewer";
            this.videoViewer.RotateAngle = 0;
            this.videoViewer.Size = new System.Drawing.Size(471, 334);
            this.videoViewer.TabIndex = 0;
            this.videoViewer.Text = "videoViewerWF1";
            // btn_Connect
            this.btn_Connect.Location = new System.Drawing.Point(12, 12);
            this.btn_Connect.Name = "btn_Connect";
            this.btn_Connect.Size = new System.Drawing.Size(152, 26);
            this.btn_Connect.TabIndex = 14;
            this.btn_Connect.Text = "Connect to WebCamera";
            this.btn_Connect.UseVisualStyleBackColor = true;
            this.btn_Connect.Click += new System.EventHandler(this.btn_Connect_Click);
            // btn_Remove
            this.btn_Remove.Location = new System.Drawing.Point(390, 12);
            this.btn_Remove.Name = "btn_Remove";
            this.btn_Remove.Size = new System.Drawing.Size(75, 23);
            this.btn_Remove.TabIndex = 1;
            this.btn_Remove.Text = "Remove";
            this.btn_Remove.UseVisualStyleBackColor = true;
            this.btn_Remove.Click += new System.EventHandler(this.btn_Remove_Click);
            // btn_Add
            this.btn_Add.Location = new System.Drawing.Point(309, 12);
            this.btn_Add.Name = "btn_Add";
            this.btn_Add.Size = new System.Drawing.Size(75, 23);
            this.btn_Add.TabIndex = 0;
            this.btn_Add.Text = "Add";
            this.btn_Add.UseVisualStyleBackColor = true;
            this.btn_Add.Click += new System.EventHandler(this.btn_Add_Click);
            // label1
            this.label1.AutoSize = true;
            this.label1.Location = new System.Drawing.Point(187, 17);
            this.label1.Name = "label1";
            this.label1.Size = new System.Drawing.Size(116, 13);
            this.label1.TabIndex = 15;
            this.label1.Text = "Histogram equalization:";
            // MainForm
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(498, 406);
            this.Name = "MainForm";
            this.Text = "Histogram equalization";



        private Ozeki.Media.VideoViewerWF videoViewer;
        private System.Windows.Forms.Button btn_Connect;
        private System.Windows.Forms.Button btn_Remove;
        private System.Windows.Forms.Button btn_Add;
        private System.Windows.Forms.Label label1;

Code 2 - Histogram equalization GUI in C#

Related Pages


With the help of this lecture you can successfully implement histogram equalization with your C# camera application using the Ozeki Camera SDK.


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

  1. What kind of developer environment is needed?

    • Microsoft Visual Studio 2010
    • Microsoft .Net Framework 4.0
    • Internet connection
  2. How can I get the URL of the camera?

    You can get the URL from the producer of the camera.

  3. 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.

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