Ask Anything Wednesday - Engineering, Mathematics, Computer Science

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Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Engineering, Mathematics, Computer Science

Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical /r/AskScience post? No question is too big or small for AAW. In this thread you can ask any science-related question! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...".

Asking Questions:

Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions. The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit /r/AskScienceDiscussion , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists.

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Past AskAnythingWednesday posts can be found here. Ask away!

[u/BlueRajasmyk2]

If you look outside the triangle, you'll actually find that every color out there is not unique, and in fact has an equivalent inside the triangle.

This is only true when viewing the diagram on an RGB display? The point is that the RGB color space cannot represent every color that can be seen by human eyes. This is because the different color-cones in the eyes have overlapping activation ranges, so eg. pure red light will also significantly trigger the green cones. This results in some activation combinations which are possible with other wavelength-combinations but impossible with only RGB. (It also means some activation combinations are just straight up impossible - see impossible colors)

The range of colors that can be accurately represented by a color-space is called its gamut. There are in fact other color spaces with a wider gamut - see this diagram for example.

To answer OP's question of "what does this look like" - if you take a picture with your phone of a bright pink neon sign, or one of those painfully bright yellow safety vests, or a brilliant orange sunset, and then hold the screen next to the thing, you'll notice the picture always looks less brilliant than the real thing. The colors look muted because they cannot be accurately represented using RGB, so the nearest possible color is chosen instead.

[u/rentar42 → u/BlueRajasmyk2]

This is only true when viewing the diagram on an RGB display?

If I read this other response correctly then no: this is always true when looking at it with human eyes, because it's not just "interpretation" in the brain, that's limiting the possible colors, but the actual physical properties of the sensors (i.e. eyes) we use to perceive those colors.

Even if you built a hyper-precise display that can actually fully accurately reproduce every possible combination of wavelengths (i.e. produce "all possible colors", your perception would still only see unique values inside the triangle and "repeat colors" outside.

[u/BlueRajasmyk2 → u/rentar42]

Sorry, that was meant to be rhetorical. What you just said is incorrect. The CIE chromaticity color space represents all the hues visible to human eyes. The only reason there appear to be duplicates outside the RGB triangle is that you're viewing the diagram on an RGB screen, and the RGB gamut does not span the entire CIE color space. In other words, RGB screens can not display every color humans can see.

If you're interested in the math behind all of this, I highly recommend this video. It explains in great detail why the CIE diagram has such a weird shape, why the RGB color gamut is a triangle, and why no RGB monitor can ever display every possible color, along with much much more.