Show HN: Simple algorithm and color space to generate diverse skin tones

Then, I thought this would stop at using the U-space vectors (the ones that form the basis of the PCA image) and their corresponding ellipse to form our color space, but no, the function fitting is a very slick idea, even if it was executed by hand.

Lastly, I love the presentation of sampling from different r values. Whether you sample from a fixed r value or a range of r values, I bet this has great applications in game design or animation.

I still don't quite get the manual data labeling process at the beginning? It seems like it would encode some bias, but the consistency of the first point cloud and the results certainly speak for themselves.

It seems like some work was done to research existing approaches, but I don't see any reference to Pantone Skin Tones [0]. Without intending to, I've worked on 3 different projects which involved measuring skin tones for makeup applications. The Pantone range is not 100% perfect, but it's pretty well done and easy to understand. There are two axes: a light/dark one, and red-yellow one [1].

[0] https://www.pantone.com/na/en-us/skintone

[1] https://cosmeticsbusiness.com/pantone-skintone-guide-80945

I was looking at this a little while ago, and used some of The Pudding's data on makeup/foundation shades (https://pudding.cool/2018/06/makeup-shades/) and plotted it into the Oklab colorspace (https://observablehq.com/@55th/foundation-shades). The shades form themselves into that same crescent as seen in the article.

Pete Shirley (author of Ray Tracing In One Weekend) is also a part time color scientist, and he clued me into the fact that if you crank the saturation to 100% of pictures of people of any race, the skin color comes out orange. I think I heard that some face detectors may work on this principle, but I don’t remember where I heard that.

"Only realistic colors" would be a different problem. And I'm not sure if there's a way to solve that problem without excluding some real colors too.

(Maybe if the colour selector was a different shape? I don't know much about color spaces.)

The 2.0 “outliers” cover those skin tones.

Masai and some Somali skin tones, similarly, look better represented by the outliers.

The full range of possible human skin tones is perhaps a bit of a challenge for technical colour representation, partly because diffuse reflectance seems to vary so much and that is hard to approximate on screen (e.g. as any website designer could attest, the difference between representing silver and grey is the use of highlights), though the representation of skin tones is a lot better than the early colour film era.

When you’re actually painting, skin can really be any color. Blue is a perfectly valid (and fairly common) skin color - just look at someone in the moonlight. It takes two to tango, and the other dancer is the light source.

Wish I had this on hand like this three or four years ago when I was working on VR avatar software - we had hard-coded skin tone options at the time - would have been a cool addition!

Nb. I'd advise against calling the PCA'd space XYZ because that's a well known standard color space: https://en.wikipedia.org/wiki/CIE_1931_color_space#CIE_XYZ_c...

There is at least one article published by a technical artist at Pixar who describes modeling a skull within a human scan so that subsurface lighting is more accurately rendered.

I suspect you could combine this with dr_scully’s comment and GolDDranks’ to reach the nuance involved in long tail realism details.

The JS code seems to output linear RGB directly to the webpage (missing gamma). I guess the difficulty with "adding gamma" to it is this: if the training data were also gamma encoded, then it might need to be refit with linear values.

From the way the article is written, it sounds like you presented yourself with a bunch of faces of completely random colours and then manually sorted them into two categories, "plausible skin colour" and "implausible skin colour".

But I feel like I must be misunderstanding, because I don't see why you would do that. Why wouldn't you gather photographs of actual faces and sample colours directly from the photos?

but this is just lovely and inspirational work. A unique marriage of hacking in the celebratory sense, thoughtfulness, and meaningful contribution. Outstanding.

So even when you get the palette right, to paint it like a believable material in a convincing way is still super hard!

Would love to see this 3-D picker ability in the many character designers out there, instead of the lame 8 swatches or whatever.

https://canopycanopycanopy.com/contents/color-goes-electric

The Kodak “Shirley cards” and test shots are of course famous in the media theory world for how they baked notions of race and “standard” or “normal” conditions into the medium of photography. Not dissimilar from the various discussions around facial recognition from approximately 10 yr ago.

https://econocrafts.com/products/crayola-colors-of-the-world...

An albino that consumed too much colloidal silver for years?