给图片添加图片水印

 system.drawing.image image = system.drawing.image.fromfile(path);

system.drawing.image copyimage = system.drawing.image.fromfile( server.mappath(".") + "/alex.gif");

graphics g = graphics.fromimage(image);

g.drawimage(copyimage, new rectangle(image.width-copyimage.width, image.height-copyimage.height, copyimage.width, copyimage.height), 0, 0, copyimage.width, copyimage.height, graphicsunit.pixel);

g.dispose();