Heeeeey, do you still need a hand? I always see the replies to my comments so damn late, sorry...
ANYWAY, I'll give you the answer anyway, just in case.
1st of all, the artword you're looking for is in Zed's route. It's not a big scene that affects the plot though, just letting you know so you don't get dissapointed. This artwork marks a very minor plot point that doesn't affect the game much. But here you go, anyway.
(Sorry, this is really long, didn't mean to make you an essay to read through XD It just sorta happened.)
When you play the game, don't play shy. What I mean, is at the very start of the game? Stand up against the shitty step dad. Flirt with the purple guy. When you're on the ship and are trying to escape, dash into that airlock and get yourself some food when you're on ship. Tell Zed "Screw Clarence". Don't hesitate when Zed tells you what to do... That's what I mean.
This personality type will triger an option, which you otherwise don't get in chapter 4. This is the situation that triggers the image for no.17.
In the scene where, after you do what Zed says without hesitating and go to the kitchen to fix the... auto-cook thingy, you guys will have a meal.
(There's an option here to help him out or point to the mess, but it won't really make a difference if you've been playing the aggressive personality. Can choose whichever you want.)
You guys will go to the showers after, which is WHERE you get the options to "Don't look!" or
"Take a peak..."
Take that goddamn peak.
Next, is where you actually get the image. This is still chapter 4, but you've now had a chat with the crew over dinner and have been bid goodnight by Zed in the Galley, after which you can wonder the ship.
Here, don't go to bed right away, you need to head over to the MED part of the ship. There, you will just automatically triger the image when looking through something.
Hope this is of use.