/// <summary>
/// change resolution of image
/// </summary>
public void resolution(float nouvelleResolution)
{
// creation of an image to the same dimension that the image source
    Bitmap tempImage = new Bitmap(monImage);
    int W=tempImage.Width, H=tempImage.Height;
// one course the image pixel by pixel to modify each one of them
    for (int li=0; li<H; li++)
    for (int col=0; col<W; col++)
    {
         tempImage.SetResolution(nouvelleResolution,nouvelleResolution);
    }
    monImage.Dispose();
    monImage = tempImage;
}

/// <summary>
/// filter transparent
/// </summary>
public void transparence(string chemin)
{
    // one creates the image since an existing image
    Bitmap curImage = new Bitmap(monImage);
    Graphics g =Graphics.FromImage(curImage);
    // // the image is drawn
    g.DrawImage(curImage, 0, 0, curImage.Width, curImage.Height);
    // one creates an object with different opacity
    SolidBrush semiTransBrush = new SolidBrush(Color.FromArgb(60, 255, 255, 0));
    // drawing of the graphic with the transparency
    g.FillRectangle(semiTransBrush, 0, 0, curImage.Width, curImage.Height);

    monImage.Dispose();
    monImage = curImage;

}

/// <summary>
/// transformation black and white
/// </summary>
public void noirBlanc()
{
// creation of an image to the same dimension that the image source
    Bitmap tempImage = new Bitmap(monImage);
    int W=tempImage.Width, H=tempImage.Height;

// course the image to modify pixel by pixel
    for (int li=0; li<H; li++)
    for (int col=0; col<W; col++)
    {
        Color c = tempImage.GetPixel(col, li);
        int gris = (c.R + c.G + c.B)/3;// definite the gray color
        tempImage.SetPixel(col, li, Color.FromArgb(gris, gris, gris));// definite the gray color
    }
    monImage.Dispose();// dispose resources of the image source
    monImage = tempImage;// attribute with the image source the new image
}