PHP吐出实际的HTML而不是图像

Having a small issue here but cannot figure out where I have gone wrong. I have the following code which should show an image depending on the condition but instead it shows the HTML in the browser

if ($this->id_status  == 2)
    {
            $this->id_status  = "<img src='../_lib/img/gray_dot.png' />";
    }
elseif ($this->id_status  == 1)
    {
            $this->id_status  = "<img src='../_lib/img/green_dot.png' />";
    }
elseif ($this->id_status  == 3)
    {
            $this->id_status  = "<img src='../_lib/img/orange_dot.png' />";
    }

Can anyone help?

try this:

<?php

    if ($this->id_status  == 2)
        {
   ?>
<img src='../_lib/img/gray_dot.png' />
<?php
        }
    elseif ($this->id_status  == 1)
        {
?>
               <img src='../_lib/img/green_dot.png' />
<?php

        }
    elseif ($this->id_status  == 3)
        {
?>
<img src='../_lib/img/orange_dot.png' />
<?php

        }
?>