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MethodicalProgrammer t1_iu93j04 wrote

Reply to comment by R3lay0 in [OC] The average colour of each European country flag. by kate1hepuppy

Because averaging colors is arbitrary and the results depend on the color space. The tool they used averages colors in non-linear sRGB which gives unexpected results when doing any kind of color math like averaging and interpolating. They could convert to a linear or perceptually uniform color space like CIEXYZ or CIELab, average, and convert back to sRGB to get a more expected result, but it's still an arbitrary result.

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R3lay0 t1_iu9ispd wrote

I don't think that's the problem here, the tool they're using gives a different value

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zetimenvec t1_iuix5ar wrote

I think they categorized the colors into "red" "blue" "green" etc, regardless of shade and then counted the colors that appear, and then took them all as appearing an uniform amount, and calculated the average that way. A very quick and napkin-mathy approach.

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R3lay0 t1_iuje6t3 wrote

But the Switzerland, Denmark and Austria should have the same color

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zetimenvec t1_iujf4gb wrote

Hm. You're right.I guess they do take surface area into consideration. I'm not sure then. I was mostly basing that theory on the UK/France comparison, because I'm pretty sure the UK has less blue in it than France's, but they're like identical colors on this average map.

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XkF21WNJ t1_iubagwi wrote

There's exactly one kind of colour space where blending colours makes any sense and it's the ones where colours are a simple linear transformation of the light spectrum. For humans you'll want to use either CIE XYZ or CIE RGB (the end result is equivalent). In these spaces blending colours has the same effect as blending light of the same colour, which is usually what you want.

If you use non-linear spaces you're not blending you're 'tweening' colours at best, doesn't matter if the space is perceptually uniform or not. This can be helpful for graphic design, but it's not physically meaningful and usually has some weird edge-cases.

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Mountain-Dealer8996 t1_iub69xy wrote

Averaging in a “perceptual” color space doesn’t really make sense because perceptual color is non-Riemannian (source)

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PaperReadingGuy t1_iuc5omh wrote

How can it not make sense if I'm a human and it makes total sense to me?

If the Switzerland flag is only red and white with a bit more red than white then the average should be the equivalent of mixing those quantities of ink.

Haven't artists averaged colors since forever using palettes?

Have you ever said what you just said to an artist that paints using a brush on a canvas and what was their reaction?

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Mountain-Dealer8996 t1_iue7ze8 wrote

No, it’s not the case that mixing equal portions of red pigment and white pigment gets you a color that is perceptually mid-way between the red and white. You might get something that looks “closer” to the red or looks closer to the white. I actually have talked about this with quite a few artists. Josef Albers (abstract expressionist painter) wrote a whole book on this topic, and other non-linearities in color perception. Personally, I did my PhD thesis on the neuroscience of color perception.

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PaperReadingGuy t1_iuf70wl wrote

I'm sorry, you could be right, but walk me through here.

If I pay an artist with brush-canvas-and-palette to mix red and white such that he can arrive at a color that is the average of the quantities of red and white on the Switzerland flag, are you saying he couldn't do that by eyeballing it?

Or are you saying he couldn't do that mechanically automatically by just mixing the exact amounts of red and white on the Switzerland flag without eyeballing it?

If you're saying the latter, that it's not automatic and the proportions are not the same as on the original flag, I could believe you, but you haven't said anything that would cause me to believe that.

If you're saying the former, there's no way I can believe in that, because then every art book on colors would have to make a major pause in explaining colors to tell me what you're trying to tell me, and no art color book does that.

Therefore it seems to me that brush-canvas-and-palette artists can totally do what you are saying can't be done - otherwise how were all the paintings that the world has accumulated in museums painted?

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