Could you load the images from the urls into memory and try out open source code[0] that detects porn (I'm sure there's probably something better out there, but this was just a quick find on github)?
I'm not sure how helpful it might be (false positives and what not), but it could help give you more numbers to quantify whats going on?
I'm not sure how helpful it might be (false positives and what not), but it could help give you more numbers to quantify whats going on?
[0] https://github.com/FreebieStock/PHP-Image-Pornographic-Conte...