Possibility 1
If it is possible to replace something in the Container-URL or Thumbnail-URL to get the direct URL to the image than you can do so.

You have to create a new rule. First you have to define a pattern for the Container-URL as regular expression, so that the rule knows for which URLs to search.
Now you can make one or more replacements behind the other.
The result from a replacement is used for the next replacement.
Only the first replacement is using the Container-URL or Thumbnail-URL.
Example
The Thumbnail-URL is: http://img411.imageshack.us/img411/5221/935871ia1.th.jpg
The search pattern is:http://(img[0-9]*)\.([a-zA-Z0-9.]*)/([a-zA-Z0-9]*)/([a-zA-Z0-9_%]*)/([a-zA-Z0-9-_%]*)\.th\.([a-zA-Z]*)
And the replacement looks like this:http://$1.$2/$3/$4/$5.$6
We get the URL:http://img411.imageshack.us/img411/5221/935871ia1.jpg

Possibility 2
You have to create a new rule. First you have to define a pattern for the Container-URL as regular expression, so that the rule knows for which URLs to search.
Then you have to select the second mode.

If the URL to the image can't get from the Container-URL, than you can let the program download the sourcecode of the webpage and you can make replacements in it.
Here you can also do more than one searches behind the other. The result from a search is the position in the sourcecode where the pattern was found.
The next search will use this position as startpoint for the search.
The last search is taking the result and is replacing it.

In the Replacement-Pattern you can use two variables:As URL we have: http://bla.irgendwas.net/ordner/bild.jpg
$SRV is replaced by the domain. So we get http://bla.irgendwas.net/
$URL is replaced by the URL without the filename. We get http://bla.irgendwas.net/ordner/

In the Search-Pattern you can use brackets to use the content as reference in the Replace-Pattern.
We take as sourcecode this:SRC="aAfkjfp01fo1i-28074/loc164/54394_NoraTschirner_FCVenusPremiere_01.jpg">
As Search-Pattern we take: SRC="(.*)">
For this bracket you can use the reference $1.
On replacing the program will also replace $1 with the content of the SRC-attribute.
You can use more than one brackets, the reference are then nummbered.
The first bracket is $1, the second is $2 and so on.
Example
The source is downloaded first.
As URL we take this:http://img7.imagevenue.com/img.php?loc=loc164&image=54394_NoraTschirner_FCVenusPremiere_01.jpg
Here is a part of the sourcecode from imagevenue:

<font color="black" face="Verdana" size=-2>
This image has been scaled down to fit your computer screen.
 Click on it to show it in the original size. <div>
</font>
</center>
 
<div>
<div>
<table border="0" width="100%" bgcolor= "white" cellspacing="0"
cellpadding="0">
 
<tr>
<td align="center" valign="top">
<img id="thepic" onClick="scaleImg('thepic')" onLoad="scaleImg('thepic')"
SRC="aAfkjfp01fo1i-28074/loc164/54394_NoraTschirner_FCVenusPremiere_01.jpg"></td>
</tr>

The first search-pattern looks like this:id="thepic"
The search finds the position of the pattern in the sourcecode.
Now we aren't at the right position, because we want the image, the content in SRC=""
So we need a second search-pattern which looks like this:SRC="(.*)">
Now we got what we want. In the program the result is written to a variable.
In this variable is now this:SRC="aAfkjfp01fo1i-28074/loc164/54394_NoraTschirner_FCVenusPremiere_01.jpg">

Now we have to define a Replace-Pattern in the last search.
In this example we need $SRV$1
The program replaces now the variable with this pattern und we get the URL:http://img7.imagevenue.com/aAfkjfp01fo1i-28074/loc164/54394_NoraTschirner_FCVenusPremiere_01.jpg