Adjusting The Contrast Of An Image.

using System;

using System.IO;

using System.Drawing;

using System.Drawing.Imaging;

using System.Collections;

using System.ComponentModel;

using System.Windows.Forms;

using System.Data;

 

namespace ImageContrast

{

  /// <summary>

  /// Summary description for Form1.

  /// </summary>

  public class Form1 : System.Windows.Forms.Form

  {

 

    Bitmap _image;

 

    float _contrastFactor=1f;

 

 

    private System.Windows.Forms.Button button1;

    private System.Windows.Forms.Button button2;

    private System.Windows.Forms.Button button3;

    private System.Windows.Forms.TrackBar trackBar1;

    private System.Windows.Forms.PictureBox pictureBox1;

    private System.Windows.Forms.Label label1;

    /// <summary>

    /// Required designer variable.

    /// </summary>

    private System.ComponentModel.Container components = null;

 

    public Form1()

    {

      //

      // Required for Windows Form Designer support

      //

      InitializeComponent();

 

      //

      // TODO: Add any constructor code after InitializeComponent call

      //

    }

 

    /// <summary>

    /// Clean up any resources being used.

    /// </summary>

    protected override void Dispose( bool disposing )

    {

      if( disposing )

      {

        if (components != null)

        {

          components.Dispose();

        }

      }

      base.Dispose( disposing );

    }

 

    #region Windows Form Designer generated code

    /// <summary>

    /// Required method for Designer support - do not modify

    /// the contents of this method with the code editor.

    /// </summary>

    private void InitializeComponent()

    {

      this.button1 = new System.Windows.Forms.Button();

      this.button2 = new System.Windows.Forms.Button();

      this.button3 = new System.Windows.Forms.Button();

      this.trackBar1 = new System.Windows.Forms.TrackBar();

      this.pictureBox1 = new System.Windows.Forms.PictureBox();

      this.label1 = new System.Windows.Forms.Label();

      ((System.ComponentModel.ISupportInitialize)(this.trackBar1)).BeginInit();

      this.SuspendLayout();

      //

      // button1

      //

      this.button1.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Right)));

      this.button1.Location = new System.Drawing.Point(448, 280);

      this.button1.Name = "button1";

      this.button1.TabIndex = 0;

      this.button1.Text = "Open";

      this.button1.Click += new System.EventHandler(this.button1_Click);

      //

      // button2

      //

      this.button2.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Right)));

      this.button2.Location = new System.Drawing.Point(448, 312);

      this.button2.Name = "button2";

      this.button2.TabIndex = 0;

      this.button2.Text = "Save";

      this.button2.Click += new System.EventHandler(this.button2_Click);

      //

      // button3

      //

      this.button3.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Right)));

      this.button3.Location = new System.Drawing.Point(448, 344);

      this.button3.Name = "button3";

      this.button3.TabIndex = 0;

      this.button3.Text = "Done";

      this.button3.Click += new System.EventHandler(this.button3_Click);

      //

      // trackBar1

      //

      this.trackBar1.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Right)));

      this.trackBar1.Location = new System.Drawing.Point(464, 88);

      this.trackBar1.Maximum = 100;

      this.trackBar1.Name = "trackBar1";

      this.trackBar1.Orientation = System.Windows.Forms.Orientation.Vertical;

      this.trackBar1.Size = new System.Drawing.Size(45, 176);

      this.trackBar1.TabIndex = 1;

      this.trackBar1.TickFrequency = 10;

      this.trackBar1.Value = 25;

      this.trackBar1.Scroll += new System.EventHandler(this.trackBar1_Scroll);

      //

      // pictureBox1

      //

      this.pictureBox1.Anchor = ((System.Windows.Forms.AnchorStyles)((((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom)

        | System.Windows.Forms.AnchorStyles.Left)

        | System.Windows.Forms.AnchorStyles.Right)));

      this.pictureBox1.Location = new System.Drawing.Point(8, 8);

      this.pictureBox1.Name = "pictureBox1";

      this.pictureBox1.Size = new System.Drawing.Size(432, 360);

      this.pictureBox1.SizeMode = System.Windows.Forms.PictureBoxSizeMode.StretchImage;

      this.pictureBox1.TabIndex = 2;

      this.pictureBox1.TabStop = false;

      //

      // label1

      //

      this.label1.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Right)));

      this.label1.Location = new System.Drawing.Point(456, 40);

      this.label1.Name = "label1";

      this.label1.Size = new System.Drawing.Size(56, 23);

      this.label1.TabIndex = 3;

      this.label1.Text = "1";

      this.label1.TextAlign = System.Drawing.ContentAlignment.MiddleCenter;

      //

      // Form1

      //

      this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);

      this.ClientSize = new System.Drawing.Size(536, 389);

      this.Controls.Add(this.label1);

      this.Controls.Add(this.pictureBox1);

      this.Controls.Add(this.trackBar1);

      this.Controls.Add(this.button1);

      this.Controls.Add(this.button2);

      this.Controls.Add(this.button3);

      this.Name = "Form1";

      this.Text = "Form1";

      ((System.ComponentModel.ISupportInitialize)(this.trackBar1)).EndInit();

      this.ResumeLayout(false);

 

    }

    #endregion

 

    /// <summary>

    /// The main entry point for the application.

    /// </summary>

    [STAThread]

    static void Main()

    {

      Application.Run(new Form1());

    }

 

    private void button1_Click(object sender, System.EventArgs e)

    {

      OpenFileDialog dlg=new OpenFileDialog();

      dlg.Filter="Image files|*.bmp; *.jpg; *.gif; *.tif; *.png";

      if(dlg.ShowDialog()==DialogResult.OK)

      {

        _image=(Bitmap)Image.FromFile(dlg.FileName,true);

        this.Text=dlg.FileName;

      }

      this.trackBar1.Value=25; //reset the contrast and update the image

      UpdateImage();

    }

 

    private void button3_Click(object sender, System.EventArgs e)

    {

      Application.Exit();

    }

 

    private void trackBar1_Scroll(object sender, System.EventArgs e)

    {

      _contrastFactor=0.04f*this.trackBar1.Value;

 

      this.label1.Text=this._contrastFactor.ToString("0.00");

      UpdateImage();

    }

 

    /// <summary>

    /// Adjusts the contrast of the image by modifying the scale of the original colours using a ColorMatrix

    /// </summary>

    void UpdateImage()

    {

      if(_image==null)

        return;

      Image oldImage=this.pictureBox1.Image; // save the old image so we can dispose of it nicely

 

      Bitmap bm=new Bitmap(this._image.Width, this._image.Height); //create a new image

      Graphics g=Graphics.FromImage(bm); //ready to draw on it

      ImageAttributes ia=new ImageAttributes();

      //create the scaling matrix

      ColorMatrix cm=new ColorMatrix(new float[][]{  new float[]{_contrastFactor,0f,0f,0f,0f},

                              new float[]{0f,_contrastFactor,0f,0f,0f},

                              new float[]{0f,0f,_contrastFactor,0f,0f},

                              new float[]{0f,0f,0f,1f,0f},

                              //including the BLATANT FUDGE

                              new float[]{0.001f,0.001f,0.001f,0f,1f}});

      //use it in the image attributes

      ia.SetColorMatrix(cm);

      //draw the original to the temporary using the matrix

      g.DrawImage(_image,new Rectangle(0,0,_image.Width,_image.Height),0,0,_image.Width,_image.Height,GraphicsUnit.Pixel,ia);

      g.Dispose(); //Don't need this anymore;

      ia.Dispose(); // or this

      this.pictureBox1.Image=bm; //replace the picture;

      if(oldImage!=null)

        oldImage.Dispose(); // get rid of the old one if it exists.

    }

 

    private void button2_Click(object sender, System.EventArgs e)

    {

      //Saves the image in the chosen format

      if(_image==null)

        return;

      SaveFileDialog dlg=new SaveFileDialog();

      dlg.Filter="Image files|*.bmp; *.jpg; *.gif; *.tif; *.png ";

      dlg.FileName=this.Text;

      if(dlg.ShowDialog()==DialogResult.OK)

      {

        this.Text=dlg.FileName;

        ImageFormat fmt=ImageFormat.Jpeg;

        switch(Path.GetExtension(dlg.FileName).ToLower())

        {

          case ".jpg":

          case ".jpeg":

            fmt=ImageFormat.Jpeg;

            break;

          case ".bmp":

            fmt=ImageFormat.Bmp;

            break;

          case ".png":

            fmt=ImageFormat.Png;

            break;

          case ".tif":

          case ".tiff":

            fmt=ImageFormat.Tiff;

            break;

          case ".gif":

            fmt=ImageFormat.Gif;

            break;

        }

        //make the image in the picturebox the working image

        this._image.Dispose();

        this.pictureBox1.Image.Save(dlg.FileName,fmt);

        this._image=(Bitmap)this.pictureBox1.Image;

      }

    }

 

  }

}