Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

What is the best way to programatically detect porn images? (2009)

stackoverflow.com

Post reply on HN
Print view View original

21–30 of 110 posts

Re: What is the best way to programatically detect porn images? (2009)

#21

Post by VLM »

hugofirth wrote: post #12

Whilst I agree that programmatically eliminating porn images is a very hard problem. Programmatically filtering porn websites might be easier, beyond just a simple key word search and whitelist. If you assume that porn tends to cluster, rather than exist in isolation, then a crawl of other images on the source pages , applying computer vision techniques, should allow you to block pages that score above a threshold nu…

"score above a threshold number of positive results"

How about social scoring? A normal (or even a weirdo) teenage boy would spend less than a second examining my ugly old profile pix, but after ten or so of your known teen male users are detected to spend 5 minutes at a time, a couple times a day, closely studying a suspected profile pix, I think you can safely conclude that pix is not a pix of me and then flag / censor / whatever it for the next 10K users.

Re: What is the best way to programatically detect porn images? (2009)

#22

Post by Shivetya »

VLM wrote: post #13

This is probably going to get downvoted, but if lots of people are not overzealous puritans and want some skin, the best overall system design that maximizes happiness and profit is probably sharding into puritanweirdos.example.com with no skin showing between toes and top of turtleneck (edited to add no pokies either) and normalpeople.example.com with 99% of the human race The best solution to a problem involving co…

Harassment laws/lawyers would find you their wet dream. The rule with pictures in any work environment is to err on the side of extreme caution.

More than likely your not going to find out they don't mesh with the team till they quit or are fired. If your lucky its not followed by a lawsuit.

See, its not their job to not be offended, it is your job to offer a harassment free work environment. Whom you are catering too depends on what is PC or not at the time, fortunately its pretty easy to determine whose whims to cater to or not

Re: What is the best way to programatically detect porn images? (2009)

#23

Post by Theodores »

In The Olden Pre-Digital Days porn was either in print or on a television screen. Back then (we are talking two whole decades ago) experienced broadcast engineers could instantly spot porn just by catching a look at an oscilloscope (of which there were usually many in a machine room).

Notionally the oscilloscope would be there to show that the luminance and chroma was okay in the signal (i.e. it could be broadcast over the airwaves to look as intended at the other end - PAL/NTSC), however, porn and anything likely to be porn had a distinctive pattern on the oscilloscope screen. Should porn be suspected then the source material would obviously be patched through to a monitor 'just in case'.

Note that the oscilloscope was analog and that the image would be changing 25/30 times a second. Also, back then there were not so many false positives on broadcast TV, e.g. pop videos etc. where today's audience deems them artful rather than porn.

If I had to solve the problem programatically I would find a retired broadcast engineer and start from there, with what can be learned from a 'scope.

Re: What is the best way to programatically detect porn images? (2009)

#24

Post by racbart »

Wouldn't testing for skin colors produce far too many false positives to be useful? All these beach photos, fashion lingerie photos, even close portraits. And how about half of music stars these days who seem to try to never get caught more clothed than half naked?

Nudity != porn and certainly half-nudity != porn.

I'd rather go for pattern recognition. There's lot of image recognition software these days that can distinguish the Eiffel Tower from the Statue of Liberty and it might be useful to detect certain body parts and certain body configurations (for these shots that don't contain any private body part but there are two bodies in an unambiguous configuration).

Re: What is the best way to programatically detect porn images? (2009)

#25

Post by _mulder_ »

Here's an idea...

Develop a bot to trawl NSFW sites and hash each image (combined with the 'skin detecting' algorithms detailed previously). Then compare the user uploaded image hash with those in the NSFW database.

This technique relies on the assumption that NSFW images that are spammed onto social media sites will use images that already exist on NSFW sites (or are very similar to). Then it simply becomes a case of pattern recognition, much like SoundHound for audio, or Google Image search.

It wouldn't reliably detect 'original' NSFW material, but given enough cock shots as source material, it could probably find a common pattern over time.

edit: I've just noticed rfusca in the OP suggests a similar method

Re: What is the best way to programatically detect porn images? (2009)

#26

Post by jiggy2011 »

Shivetya wrote: post #22
VLM wrote: post #13

This is probably going to get downvoted, but if lots of people are not overzealous puritans and want some skin, the best overall system design that maximizes happiness and profit is probably sharding into puritanweirdos.example.com with no skin showing between toes and top of turtleneck (edited to add no pokies either) and normalpeople.example.com with 99% of the human race The best solution to a problem involving co…

Harassment laws/lawyers would find you their wet dream. The rule with pictures in any work environment is to err on the side of extreme caution. More than likely your not going to find out they don't mesh with the team till they quit or are fired. If your lucky its not followed by a lawsuit. See, its not their job to not be offended, it is your job to offer a harassment free work environment. Whom you are catering to…

I'm not sure it is that easy, even HN discussions on the topic don't come to any particular conclusion and that is within a fairly narrow range of people.

In an old job I had the task of cleaning spam off a forum, this meant looking at rather a lot of porn but it would never have occurred to me to sue on that basis, yet that is still a job that needs to be done.

Re: What is the best way to programatically detect porn images? (2009)

#27

Post by Daniel_Newby »

Shivetya wrote: post #22
VLM wrote: post #13

This is probably going to get downvoted, but if lots of people are not overzealous puritans and want some skin, the best overall system design that maximizes happiness and profit is probably sharding into puritanweirdos.example.com with no skin showing between toes and top of turtleneck (edited to add no pokies either) and normalpeople.example.com with 99% of the human race The best solution to a problem involving co…

Harassment laws/lawyers would find you their wet dream. The rule with pictures in any work environment is to err on the side of extreme caution. More than likely your not going to find out they don't mesh with the team till they quit or are fired. If your lucky its not followed by a lawsuit. See, its not their job to not be offended, it is your job to offer a harassment free work environment. Whom you are catering to…

Nope. Harrassment is a legal term of art, not a synonym for disagreeable treatment. Harrassment occurs when a person or group is singled out for distinct treatment, in the U.S. at least. Subjecting everybody to all types of porn is quite lawful. (There is a famous case of a bisexual pervert who indiscriminantly propositioned anything with a pulse. His self-designated victims were bitch slapped out of court.)

Re: What is the best way to programatically detect porn images? (2009)

#28

Post by betterunix »

racbart wrote: post #24

Wouldn't testing for skin colors produce far too many false positives to be useful? All these beach photos, fashion lingerie photos, even close portraits. And how about half of music stars these days who seem to try to never get caught more clothed than half naked? Nudity != porn and certainly half-nudity != porn. I'd rather go for pattern recognition. There's lot of image recognition software these days that can dis…

"detect certain body parts"

When I was a kid, we had a firewall at school that tried to filter pornography by doing something similar with text. Doing research on breast cancer turned out to be rather tricky.

So let's say you try to detect certain body parts. Now you have someone who wants to know more about their body, but you are classifying images from medical / health articles as pornography.

"certain body configurations"

So now instead of having trouble reading about my own body, I will have trouble looking at certain martial arts photos:

https://upload.wikimedia.org/wikipedia/commons/1/14/BostonKe...

I am not saying these are unsolvable problems, but they are certainly hard problems. Even using humans to filter images tends to result in outrageous false positives sometimes:

http://abcnews.go.com/Health/breastfeeding-advocates-hold-fa...

Re: What is the best way to programatically detect porn images? (2009)

#30

Post by arjunnarayan »

Shivetya wrote: post #22
VLM wrote: post #13

This is probably going to get downvoted, but if lots of people are not overzealous puritans and want some skin, the best overall system design that maximizes happiness and profit is probably sharding into puritanweirdos.example.com with no skin showing between toes and top of turtleneck (edited to add no pokies either) and normalpeople.example.com with 99% of the human race The best solution to a problem involving co…

Harassment laws/lawyers would find you their wet dream. The rule with pictures in any work environment is to err on the side of extreme caution. More than likely your not going to find out they don't mesh with the team till they quit or are fired. If your lucky its not followed by a lawsuit. See, its not their job to not be offended, it is your job to offer a harassment free work environment. Whom you are catering to…

I mean, if you read between the lines from his class notes, this is basically what Peter Thiel says: Just don't hire these people. Nobody will say it publicly, because that opens them up to discrimination lawsuits, but that's the reality on the ground.
Post reply on HN