function resize_img(img_id,max_width,max_height){
	var new_width;
	var new_height;
	if(img_id.width/img_id.height>max_width/max_height){
		new_width=max_width;
		new_height=img_id.height*(max_width/img_id.width);
	}else{
		new_height=max_height;
		new_width=img_id.width*(max_height/img_id.height);
	}
	img_id.width=new_width;
	img_id.height=new_height;
}