I downloaded the ImageNet ILSVRC 2012 training set (via academictorrents.com) to experiment. According to the website, this synset (doors) is in the ‘ImageNet 2011 Fall Release’, but it’s not in the ILSVRC 2012 training set:
It seems the competition sets are a subset of the full ImageNet dataset. I haven’t been able to find anywhere that lists what synsets were present in what year, but there are some pages listing what’s in the competition, and those lists don’t list the synset above at all for example (not in any year), even though it’s definitely in the full dataset.
Maybe the ‘2011’ label in their image browser is just out of date, and this synset was added after 2012?
So, is there a way to get hold of the full dataset? I’m not in academia, just learning and experimenting on my own, so even though I could get hold of an alumnus .ac.uk email address I feel a bit weird about the idea of claiming to ‘belong to’ my old institution so I can approach them for a copy (they’re understandably focused on research in academia). Of course one can fetch the images oneself by just downloading the URLs, but a lot of the photos have dropped off the web since the list of URLs was compiled.