codice:
//-------------------------------------------------------------------------
//questa procedura, data una immagine bmpSource, la ritaglia secondo il
//rettangolo clip passato
//-------------------------------------------------------------------------
public static void ImgClip(ref Bitmap bmpSource, Rectangle clip)
{
	Bitmap bmp = new Bitmap(clip.Width, clip.Height, bmpSource.PixelFormat);
	bmp.SetResolution(bmpSource.HorizontalResolution, bmpSource.VerticalResolution);
	Graphics gr = Graphics.FromImage(bmp);
	gr.Clear(Color.White);

	//'imposto lavoro alta qualità
	gr.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
	gr.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
	gr.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;
	gr.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;


	gr.DrawImage(bmpSource, new Rectangle(0, 0, clip.Width, clip.Height), clip, GraphicsUnit.Pixel);
	gr.Dispose();
	bmpSource.Dispose();
	bmpSource = bmp;

}