[ic] using if clause with area in template to adjust image

[Nicholas Cook]

Currently, in the templates, the foundation catalog uses

     [if session logged_in]
       <img alt="[L]Log Out[/L]" border="0" 
src="__THEME_IMG_DIR__logout.gif"></a>
     [else]
       <img alt="[L]Log In[/L]" border="0" 
src="__THEME_IMG_DIR__login.gif"></a>
     [/else]
     [/if]

for the login/logout image.

I tried to extend this to the following:

  [if area index]
       <img alt="Home" border="0" src="__THEME_IMG_DIR__home_tan.png"></a>
     [else]
       <img alt="Home" border="0" src="__THEME_IMG_DIR__home_green.png"></a>
     [/else]
     [/if]

But this does not adjust the image according to what page the individual 
is on?  Does anybody have any thoughts/wisdom on how to make this work?

Thank you,
Nicholas Cook