What is the best way to programmatically detect po

Question

Akismet does an amazing job at detecting spam comments. But comments are not the only form of spam these days. What if I wanted something like akismet to automatically detect porn images on a social networking site which allows users to upload their pics, avatars, etc?

There are already a few image based search engines as well as face recognition stuff available so I am assuming it wouldn't be rocket science and it could be done. However, I have no clue regarding how that stuff works and how I should go about it if I want to develop it from scratch.

How should I get started?

Is there any open source project for this going on?

Answer 1

The BrightCloud web service API is perfect for this. It's a REST API for doing website lookups just like this. It contains a very large and very accurate web filtering DB and one of the categories, Adult, has over 10M porn sites identified!

Answer 2

I would rather allow users report on bad images. Image recognition development can take too much efforts and time and won't be as much as accurate as human eyes. It's much cheaper to outsource that moderation job.

Take a look at: Amazon Mechanical Turk

"The Amazon Mechanical Turk (MTurk) is one of the suite of Amazon Web Services, a crowdsourcing marketplace that enables computer programs to co-ordinate the use of human intelligence to perform tasks which computers are unable to do."

Answer 3

A graduate student from National Cheng Kung University in Taiwan did a research on this subject in 2004. He was able to achieve success rate of 89.79% in detecting nude pictures downloaded from the Internet. Here is the link to his thesis: The Study on Naked People Image Detection Based on Skin Color
It's in Chinese therefore you may need a translator in case you can't read it.

Answer 4

Look at file name and any attributes. There's not nearly enough information to detect even 20% of naughty images, but a simple keyword blacklist would at least detect images with descriptive labels or metadata. 20 minutes of coding for a 20% success rate isn't a bad deal, especially as a prescreen that can at least catch some simple ones before you pass the rest to a moderator for judging.

The other useful trick is the opposite of course, maintain a whitelist of image sources to allow without moderation or checking. If most of your images come from known safe uploaders or sources, you can just accept them bindly.

Answer 5

Seems to me like the main obstacle is defining a "porn image". If you can define it easily, you could probably write something that would work. But even humans can't agree on what is porn. How will the application know? User moderation is probably your best bet.

Answer 6

This is a nudity detector. I haven't tried it. It's the only OSS one I could find.

https://code.google.com/p/nudetech