Converting an RGB image to 1 bit-per-pixel monochrome（源码）

using System;

using System.Drawing;

using System.Drawing.Drawing2D;

using System.Drawing.Imaging;

using System.Collections;

using System.ComponentModel;

using System.Windows.Forms;

using System.Data;

using System.Runtime.InteropServices;

namespace _1bitmap

{

/// <summary>

/// Summary description for Form1.

/// </summary>

public class Form1 : System.Windows.Forms.Form

{

    /// <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

      //

      SetStyle(ControlStyles.ResizeRedraw,true);

    }

    /// <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.pictureBox1 = new System.Windows.Forms.PictureBox();

      this.splitter1 = new System.Windows.Forms.Splitter();

      this.pictureBox2 = new System.Windows.Forms.PictureBox();

      this.SuspendLayout();

      //

      // pictureBox1

      //

      this.pictureBox1.BackColor = System.Drawing.Color.White;

      this.pictureBox1.Dock = System.Windows.Forms.DockStyle.Left;

      this.pictureBox1.Name = "pictureBox1";

      this.pictureBox1.Size = new System.Drawing.Size(100, 397);

      this.pictureBox1.TabIndex = 0;

      this.pictureBox1.TabStop = false;

      this.pictureBox1.Click += new System.EventHandler(this.pictureBox1_Click);

      //

      // splitter1

      //

      this.splitter1.Location = new System.Drawing.Point(100, 0);

      this.splitter1.Name = "splitter1";

      this.splitter1.Size = new System.Drawing.Size(3, 397);

      this.splitter1.TabIndex = 1;

      this.splitter1.TabStop = false;

      //

      // pictureBox2

      //

      this.pictureBox2.BackColor = System.Drawing.Color.FromArgb(((System.Byte)(128)), ((System.Byte)(255)), ((System.Byte)(255)));

      this.pictureBox2.Dock = System.Windows.Forms.DockStyle.Fill;

      this.pictureBox2.Location = new System.Drawing.Point(103, 0);

      this.pictureBox2.Name = "pictureBox2";

      this.pictureBox2.Size = new System.Drawing.Size(473, 397);

      this.pictureBox2.TabIndex = 2;

      this.pictureBox2.TabStop = false;

      //

      // Form1

      //

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

      this.ClientSize = new System.Drawing.Size(576, 397);

      this.Controls.AddRange(new System.Windows.Forms.Control[] {

                                      this.pictureBox2,

                                      this.splitter1,

                                      this.pictureBox1});

      this.Name = "Form1";

      this.Text = "Form1";

      this.Load += new System.EventHandler(this.Form1_Load);

      this.ResumeLayout(false);

    }

    #endregion

    /// <summary>

    /// The main entry point for the application.

    /// </summary>

    [STAThread]

    static void Main()

    {

      Application.Run(new Form1());

    }

    protected void SetIndexedPixel(int x,int y,BitmapData bmd, bool pixel)

    {

      int index=y*bmd.Stride+(x>>3);

      byte p=Marshal.ReadByte(bmd.Scan0,index);

      byte mask=(byte)(0x80>>(x&0x7));

      if(pixel)

        p |=mask;

      else

        p &=(byte)(mask^0xff);

      Marshal.WriteByte(bmd.Scan0,index,p);

    }

    private System.Windows.Forms.PictureBox pictureBox1;

    private System.Windows.Forms.Splitter splitter1;

    private System.Windows.Forms.PictureBox pictureBox2;

    Bitmap bm;

   

    private void Form1_Load(object sender, System.EventArgs e)

    {

    }

    private void pictureBox1_Click(object sender, System.EventArgs e)

    {

      //Load a file

      OpenFileDialog dlg = new OpenFileDialog();

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

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

      {

        Bitmap img = (Bitmap)Image.FromFile(dlg.FileName);

        //Ensure that it's a 32 bit per pixel file

        if(img.PixelFormat!=PixelFormat.Format32bppPArgb)

        {

          Bitmap temp=new Bitmap(img.Width,img.Height,PixelFormat.Format32bppPArgb);

          Graphics g=Graphics.FromImage(temp);

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

          img.Dispose();

          g.Dispose();

          img=temp;

        }

        this.pictureBox1.Image=img;

        //lock the bits of the original bitmap

        BitmapData bmdo=img.LockBits(new Rectangle(0,0,img.Width,img.Height),ImageLockMode.ReadOnly,img.PixelFormat);

        //and the new 1bpp bitmap

        bm=new Bitmap(this.pictureBox1.Image.Width,this.pictureBox1.Image.Height,PixelFormat.Format1bppIndexed);

        BitmapData bmdn=bm.LockBits(new Rectangle(0,0,bm.Width,bm.Height),ImageLockMode.ReadWrite,PixelFormat.Format1bppIndexed);

        //for diagnostics

        DateTime dt=DateTime.Now;

       

        //scan through the pixels Y by X

        int x,y;

        for(y=0;y<img.Height;y++)

        {

          for(x=0;x<img.Width;x++)

          {

            //generate the address of the colour pixel

            int index=y*bmdo.Stride+(x*4);

            //check its brightness

            if(Color.FromArgb(Marshal.ReadByte(bmdo.Scan0,index+2),

                            Marshal.ReadByte(bmdo.Scan0,index+1),

                            Marshal.ReadByte(bmdo.Scan0,index)).GetBrightness()>0.5f)

              this.SetIndexedPixel(x,y,bmdn,true); //set it if its bright.

          }

        }

        //tidy up

        bm.UnlockBits(bmdn);

        img.UnlockBits(bmdo);

        //show the time taken to do the conversion

        TimeSpan ts=dt-DateTime.Now;

        System.Diagnostics.Trace.WriteLine("Conversion time was:"+ts.ToString());

        //display the 1bpp image.

        this.pictureBox2.Image=bm;

      }

    }

}

}