Which Images in Web Search?

When not the first 3 images in image search, how is the order chosen?

[nuevojefe]

If you do a few searches that return images atop the natural search results you may notice that at times the images shown are NOT the first three results if you do that same search via google image search.

So, when the images shown are not simply the first 3 images from that query's image search results... how are they chosen? I thought maybe it was removing any that fell outside of the "safe search" realm. Not the case. With safe-search on for images it still returns results whose first three listings are not the 3 images shown atop the web search results.

Ideas on how they are chosen and why certain terms invoke this behavior?

[nuevojefe]

*bump* Anyone?