indyank - 2:32 pm on Aug 13, 2012 (gmt 0)
Since you have used "noindex, follow", they should still follow the direct image links. Did you also "nofollow" all internal links to those pages that only have the individual large images? Have you ruled out all other reasons?
This example increases my suspicion on their treating pages with "noindex" or "noindex, follow" meta tags as equivalent to "noindex, nofollow" increases.