private Bitmap CreateScreenshot(Control Control, int x, int y)
{
	Bitmap Screenshot = new Bitmap(1000, 1000);

	Control.DrawToBitmap(Screenshot, new Rectangle(x, y, Control.Width, Control.Height));
	return Screenshot;
}

private void resimAl()
{

	IHTMLDocument2 doc = (IHTMLDocument2)Wb1.Document.Window.Frames.Item(0).Document.DomDocument;
	mshtml.IHTMLSelectionObject sobj = doc.selection;
	mshtml.HTMLBody body = doc.body as mshtml.HTMLBody;
	sobj.empty();
	mshtml.IHTMLControlRange range = body.createControlRange() as mshtml.IHTMLControlRange;
	int a = Wb1.Document.Window.Frames.Item(0).Document.Images.Count;

	mshtml.IHTMLControlElement img = (mshtml.IHTMLControlElement)Wb1.Document.Window.Frames.Item(0).Document.GetElementById("captcha_image").DomElement;

	range.@add(img);
	range.@select();
	range.execCommand("Copy", false, null);

	Bitmap bimg = new Bitmap(Clipboard.GetImage());
	PictureBox1.Image = bimg;

}

zamanında yaptıgım bir projeden picturebox1 captcha imajı için, wb1 de webbrowser kodu incelersen anlarsın zaten