

An Algorithm for Nudity Detection [pdf] - symisc_devel
http://vidcat.org/papers/an-alogorithm-for-nudity-detection.html

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chewxy
When I was in the advertising business, one of the core products I created was
a brandsafety product - basically preventing advertisers from advertising on
dodgy sites.

I messed around with algorithms that detected nudity (because big brand
advertisers don't want their ads showing up on porn sites). One of the more
interesting and simple-to-use one is actually a simple averaging of the images
across multiple samples. That one was easy to implement and has relatively
good results.

In the end though, I ended up not using it because text clustering algorithms
worked better in classifying content.

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nathancahill
"The training set for the skin filter consisted of 1,182,608 manually labeled
skin pixels and 10,471,553 manually labeled non-skin pixels while the testing
set consisted of 2,303,824 manually labeled skin pixels and 24,285,952
manually labeled non-skin pixels."

That's a lot of pixels to manually label.

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fryguy
40 million pixels is roughly 40 ~1 megapixel (1280x720) images. It's not that
many, especially when it's likely something like this:
[http://pascallin.ecs.soton.ac.uk/challenges/VOC/images/voc20...](http://pascallin.ecs.soton.ac.uk/challenges/VOC/images/voc2005_13c.html)

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nathancahill
You're right. Didn't do the math.

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adam-f
This could only be a very rough first-pass on detection. Bathing suits can be
very skimpy without being fully nude.

And social context plays a large role, for instance distinguishing between a
fat male's nipples and a small-chested female's nipples would be impossible
without analyzing a lot more than skin color.

[http://i.imgur.com/sb6Iw.jpg](http://i.imgur.com/sb6Iw.jpg)

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dclowd9901
Seems like a not very scalable approach to the problem. I would think if you
wanted to capture _all_ nudity (including monochromatic or illustrated), you
would instead go at the problem from the angle of _titillation_. You could
even round up images that are not necessarily human based (fruit arranged
provocatively, for instance).

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benched
If the algorithm gets aroused, return positive, otherwise return negative.
Bam, patent.

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wlievens
So your algorithm would be a MTurk api?

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ivan_ah
direct link:
[http://onebit.us/x/i/814381733331796005.pdf](http://onebit.us/x/i/814381733331796005.pdf)

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saganus
Uhmm... I think I've seen this somewhere else...

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ganduG
I wrote a really quick Python implementation of this a few months ago, in case
someone is interested: github.com/ParthGandhi/nude.py

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jplur
I'm under the impression that Google's machine learning is already filtering
your personal G+ photos for nudity.

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plg
maybe the best nudity detector API involves the following:

1\. attempt to post the image to google+

2\. if the post is there, there is no nudity;

    
    
       if it failed to post, there is nudity

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BlackDeath3
So, G+ as middleware?

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nader
Does anybody know if there is an API that does this?

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notastartup
how do these nudity detection API work? Is there a crowdsourcing going
underneath the hood? Are they using some clustering algorithm to detect a
range of skin color (if 90%), it's nude.

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cmelbye
The link that you just commented on answers your question in literally the
best way possible, it's an academic paper on an algorithm used for this.

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laumars
To be fair, he may have tried that. The site is completely unusable on a phone
as it seems to make assumptions about the minimum screen resolution and
doesn't allow you to zoom out like most desktop sites on a mobile screen do.
In fact it's one of the most poorly designed sites I've stumbled upon in a
long time in that regard (which is a great pity as the content looked
interesting)

