What counts as objectification?

I was having this discussion with some of my significant others, and I thought it would be interesting to see what all of you think.

It started with a discussion of the fuckyeahhperfectdolls tumblr, (CAUTION - link is NSFW,) and how most of the people pictured can be, well... rather hard to look at for someone with body image issues.

I commented that I see the pictures on that site more as art than as people, (if you're avoiding clicking through, the majority of it is women posing either nude or scantily clad, mostly to show off their tattoos,) and I started wondering if that counts as objectification.

At least one other person in the discussion seemed to be of the opinion that it is not, because objectification is seen more as being degrading, whereas seeing someone as art, especially when they're sort of deliberately acting as a canvas for artwork to begin with, (eg, posing in such a way to show off your tattoos,) then it's more idealization than objectification. But are those two things really so different?

So, what exactly does count as objectification? I mean, that word gets used a lot, especially in respects to porn, and seeing people as sex objects, but does that mean that anyone who looks at porn is objectifying?

Does imagining yourself in someone else's place, sexually, count as objectification? What about imagining your partner in someone's place, or imagining the person onscreen as being in bed with you?

What do you think? I'd love to hear your opinions on the subject.