Re Anyone who thinks that a category based solution can work because we have enough categorisors, may I suggest that you go to http://commons.wikimedia.org/wiki/Category:Images_from_the_Geograph_British… And try categorising 0.01% of that part of the backlog yourself before being so over optimistic about our categorisation resources. When we've cleared all the subscategories in there then maybe I could be convinced that Commons has enough categorisors to handle what it already does. Taking on a major new obligation would be another matter though, even if that obligation could be defined and its categories agreed. A categorisation approach also has the difficult task of getting people to agree what porn is. This is something that varies enormously around the world, and while there will be some images that we can all agree are pornographic, I'm pretty sure there will be a far larger number where people will be genuinely surprised to discover that others have dramatically different views as to whether they should be classed as porn. For some people this may seem easy, anything depicting certain parts of the human anatomy or certain poses is pornographic to them. But different people will have a different understanding as to which parts of the body should be counted as pornographic. Getting the community to agree whether all images depicting human penises are pornographic will not be easy, and that's before you get into arguments as to how abstract a depiction of a penis has to be be before it ceases to be an image of a penis. We also need to consider how we relate to outside organisations, particularly with important initiatives such as the GLAM program. This mildly not safe for work image http://commons.wikimedia.org/wiki/File:JinaVA.jpg is a good example of the challenge here. To those concerned about human penises it may well count as pornographic, though the museum that has it on display certainly does not bar children from that gallery. This image was loaded by one of our GLAM partners, our hope for the GLAM project is that hundreds of partners will load millions perhaps tens of millions of images onto Commons. If that succeeds then our current categorisation backlog will be utterly dwarfed by future backlogs. If we start telling GLAM partners that yes we want them to upload images, but they will need to categorise them through an ill defined and arbitrary offensiveness criteria, then our GLAM program will have a problem. In principle I support an image filter, I've even proposed one design. But if people want to go down the route of a category based image filter they don't just have to convince the many who oppose any filter as censorship, they also need to be aware that to me and probably others GLAM is core to our mission and important, whilst an image filter is non-core and of relatively low importance. If the two conflict then choosing between them would be easy. If people want to advocate a categorisation approach to an image filter I would suggest they start with the difficult areas of defining where the boundary would be between porn and non-porn, or between hardcore and softcore. Drawing clear and sharp lines between different shades of grey is not easy, especially where you want them to be perceived as right by a globally diverse population. My advice to anyone considering a category based filter system is to focus on the shades of grey, not at the extreme examples on the uncontentious contentious scale. Then if you manage to square that particular circle an equally difficult task would be to recruit sufficient categorisers. As someone who has categorised many hundreds of the Geograph images I'd be surprised to find any Geograph images that I would be offended by. The sort of statues of topless ladies that you find on display in England certainly don't offend me, but bare breasts are pornographic to some people in some contexts. So there will be some long uncategorised images amongst the 1.7 million from the Geograph load that meet some peoples definition of porn. Any categorisation based approach needs to explain how it would recruit more categorisers, retain those we have, and get those volunteers to work to a categorisation scheme that for many will seem arbitrary and foreign to their culture. As for "I doubt that anyone doing so is going to be too bothered whether they've falsely censored an image that is in Category:Sex". Quality matters to Wikimedians, false positives and a tolerance for shoddy work offend almost all of us. A large proportion of the community don't approve of censorship even if it was done conscientiously and with a deep concern for getting it right. Personally I'm in the camp that thinks we could justify an image filter as part of making our data available to some of the people we don't currently reach; But I'm all too aware that there are Wikimedians who are not just bothered by inaccurate censorship, but who consider any censorship to be out of scope and Foundation money spent on it to be a misuse of charitable funds. Simply asserting that such people don't exist is unlikely to get them to agree to any form of censorship, better in my view to try and design a censorship tool that would give a high quality result. WereSpielChequers