网址ID与显示的图像不对应

I'm building my first MVC project and I need some help. I need to display image with 2 links previous and next. So here is what I've done

Controller

function nextImg(){
    $id = $this -> setImgId();
    $size = $this -> setImgSize();
    $nbimg = $this -> setImgNb();
    $id= $this->ImageDAO->getNextImage($id);
    $img_path = $this->ImageDAO->getMultipleImg($id, $nbimg);
    require_once("view/viewPhoto.php");
}

Model

public function getMultipleImg($id, $nbimg) {
            if($id == null){
                $id=1;
            }
                $s = $this->db->query('SELECT path FROM image LIMIT '.$id.', '.$nbimg.'');
                $res = $s->fetchAll();
                for($i=0;$i<count($res);$i++){
                    $list[$i] = $res[$i]['path'];
                }
                return $list;
}
function getNextImage($id) {
        $id = $id+1;
        return $id;
}

View

for($i=0; $i<count($img_path); $i++)
           {  
             print "<img src=\"$img_path[$i]\" width=\"$size\" height=\"$size\">
";
}

print "<li><a href=\"?controller=Display&id=".$id."&size=".$size."&nbimg=".$nbimg."&action=prevImg\">prev</a></li>
";
print "<li><a href=\"?controller=Display&id=".$id."&size=".$size."&nbimg=".$nbimg."&action=nextImg\">next</a></li>
";

The problem is that when I click the next or previous button, the ID in the URL is the ID of the image previously displayed. Where the problem comes from ?

I think the first three lines are supposed to be getters not setters:

  $id = $this -> getImgId();
  $size = $this -> getImgSize();
  $nbimg = $this -> getImgNb();