How do I make image locations consistent?

[makeshift]

For a while now, the way I've templated my websites is I make a sys_html.php file that contains two functions:

showHeader();
// and 
showFooter();

both return html to the user of the layout everything before and after the content.

So when making a webpage all i have to do is:

<?php
session_start();
include_once("sys_html.php");
echo showHeader();

?>
// html etc etc etc
<?

echo showFooter();
?>

The problem is, say I wanted to create a directory for organization called, uh, "products" so like my files would be like

/products/index.php, etc.

If I include "../sys_html.php" then all the image locations get screwed up.

All of my images in sys_html are done this way:

<img src='images/imagewhatever.jpg'>

so that now it TRIES to look for

/products/images/imagewhatever.jpg

and cannot find it. how do i fix this problem so that the images all work?

[devinemke]

make all of your paths absolute starting from the document root:

<?
session_start(); 
include_once($_SERVER['DOCUMENT_ROOT'] . '/sys_html.php');
echo showHeader();
?>

// html etc etc etc 
<img src="<? echo $_SERVER['DOCUMENT_ROOT'] ?>/images/imagewhatever.jpg">

<? 
echo showFooter();
?>

[makeshift]

touche.