I've tested this on my own board to make sure it works lol
Save original code first
Additional CSS Definitions add:
.guestDisplaynone img {display:none;}
Postbit or postbit_legacy replace:
<!-- message -->
<div id="post_message_$post[postid]">
$ad_location[ad_showthread_firstpost_start]
$post[message]
</div>
<!-- / message -->
With:
<!-- message -->
<if condition="$show['guest']">
<div id="post_message_$post[postid]" class="guestDisplaynone">
$ad_location[ad_showthread_firstpost_start]
$post[message]
</div>
<else />
<div id="post_message_$post[postid]">
$ad_location[ad_showthread_firstpost_start]
$post[message]
</div>
</if>
<!-- / message -->This will prevent any images within the post section from displaying and you can add in a link to register to view images in the post underneath the first $post[message] like so if wanted:
<center><a class="smallfont" href="register.php$session[sessionurl_q]" rel="nofollow">This post may contain images, please register to view them.</a>
</center>Hope that helps!