Complex loops - SECTIONS

Hi,

I am basically trying to do the following and need some help.

{section name=count loop=$Photos start=1 step=4}
<tr>
<td>{$Photos[count].Filename}</td><td>{$Photos[count+1].Filename}</td><td>{$Photos[
count+2].Filename}</td><td>{$Photos[count+3].Filename}</td>
</tr>
{/section}

Because my step is 4, I wanna print all the photos from 1-4 in the first row
 and then 5-8 in the second and so on...

Thanks in advance
HarryG