Modifier la couleur d’une image

/*
Extrait du livre Programming in C# and VB .NET
par Nick Symmonds
 
Maison d'edition: Apress
ISBN: 159059035X
*/
 
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;
 
namespace BitmapColor_c
{
    ///
<summary>
    /// Summary description for Form1.
    /// </summary>
 
    public class BitmapColor : System.Windows.Forms.Form
    {
        ///
<summary>
        /// Required designer variable.
        /// </summary>
 
        private System.ComponentModel.Container components = null;
        String urlImage = @"C:Documents and SettingsAdministrateurMes documentshalf.png";
        public BitmapColor()
        {
            //
            // 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 );
        }
 
        ///
<summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
 
        private void InitializeComponent()
        {
      //
      // Form1
      //
      this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
      this.ClientSize = new System.Drawing.Size(292, 273);
      this.Name = "Form1";
      this.Text = "Form1";
      this.Load += new System.EventHandler(this.Form1_Load);
 
        }
 
        ///
<summary>
        /// The main entry point for the application.
        /// </summary>
 
      [STAThread]
        static void Main()
        {
            Application.Run(new BitmapColor());
        }
 
        private void Form1_Load(object sender, System.EventArgs e)
        {
          ColorPalette cp;
          String s;
          Bitmap bmp = new Bitmap(urlImage);
 
          cp = bmp.Palette;
 
          foreach (Color c in cp.Entries)
          {
            s = c.ToString();
          }
 
        }
 
        protected override void OnPaint(PaintEventArgs e)
        {
 
          Bitmap bmp = new Bitmap(urlImage);
          Color c;
 
          e.Graphics.DrawImage( bmp, 10, 30 );
 
          for ( int x=0; x<bmp.Width-1; x++ )
          {
            for ( int y=0; y<bmp.Height-1; y++ )
            {
              c = bmp.GetPixel( x, y );
              c = Color.FromArgb( c.ToArgb() + 100 );
              bmp.SetPixel( x, y, c );
            }
          }
          e.Graphics.DrawImage( bmp, 150, 30 );
        }
    }
}