It doesn't really need to, it just needs to expect it to be skin. I'll probably get some terms wrong here as it's been a little while since I did this kind of

It doesn't really need to, it just needs to expect it to be skin. I'll probably get some terms wrong here as it's been a little while since I did this kind of thing but: When you look at skin, people seem to have very different colourings. I've got freckles so I'm even patchy, and depending on the time of year will be lighter or darker. However, skin colour when you remove brightness becomes much more standard. There's remarkably little variation between a normalised colour of black and white skin, black skin is simply darker. Look at the water by the faces, it's quite a generically caucasian colour. That's because it's just lighter. Here's some old stuff I did with finger pointing detection: https://figshare.com/articles/Finger_pointing_detection/953171 https://figshare.com/articles/Finger_pointing_detection/9531... https://ndownloader.figshare.com/files/3155228 https://ndownloader.figshare.com/files/3155228 <- A plot of measured skin colours https://ndownloader.figshare.com/files/3155291 https://ndownloader.figshare.com/files/3155291