question for [d. o. u .g], or anyone who wants to help

[mesman00]

i was just wondering about the mupen64 background:
http://mupen64.emulation64.com/bg.gif
how do u make it so they are cut off perfectly on top, and perfectly on bottom, so they match up when its tiled. is there an option that you select in photoshop (or whatever program) to do this automatically, or do u have to do it manually?? i was just curius becuase ive seen this before and never really new how to do it.

[[d.o.u.g]]

I'm not sure if there's an option to do this... Anyway, i did it manually. I just did the image, flatten and used the marquee tool.