For what it's worth, I spent about a decade trying to chase down that answer.

If you bet $3,000 that "we have no idea what we're doing" is an accurate assessment, you'd win.

How can that be? Because color science is very difficult. Your eyes are designed to fool you.

When you're born into a certain time period -- a random slice of human history -- the probability the dominant school of thought is mistaken is nearly 1. Wouldn't it be remarkable if we were the first generation who figured out all the truths?

The hardest part is admitting to yourself that it might be true. Could it be possible? Has the world collectively been using techniques that are nowhere close to the final answer?

I launched myself into that question with an open mind. As far as I can tell, the answer is yes.

From having worked in the industry, it's pretty accurate to say that most graphics programmers haven't read any books on color, or the human visual system. I nearly didn't. I was dragged into it because I kept getting strange answers when I tried to mix colors and quantify the diffs -- I was trying to do the same experiment that CIE 1931 did, but I got very different results. That led me to the Musnell color system, and to the history of color theory.

If you glance over the history, you'll notice that our understanding of color keeps changing. The models keep being updated; we can never quite figure out whether they're right. If CIE was perfectly accurate, we'd never have invented LAB space, because CIE would perfectly match nature. Right?

Musnell tried a different approach. Rather than coming up with a fine-sounding theory and curve-fitting it to the data, he built a model directly from the data. One of the most powerful techniques at our disposal is to use our own eyes as a null instrument. You have to have absolute confidence in your own judgement -- I cannot overstate how easy it is to fool yourself -- but if you are as methodical as a robot, you can come up with surprising answers. When those answers contradict the established science that everyone believes, you start to worry. Maybe you weren't careful enough, right? They must know what they're doing; this is what everyone believes, after all.

No... At the end of it, you discover that it really is that strange. Color science is one of the hardest to quantify. There are hard answers, but only when you strip away all the context your eyes relies on. When you look at something, you see literally a million clues that tell your brain it's a 3D shape and that X color is brighter than Y because of Z. Nature has spent a billion years evolving your brain to be able to process all of that instantly. It's impossible to be consciously aware of everything that's happening.

The only way to answer your question is to (a) come up with a methodical test, (b) conduct it meticulously, then (c) trust in yourself and the fact that you are competent and were extremely careful.

If you do all three of those things, you will be dragged kicking and screaming to the conclusion that not one person anywhere in the world has any idea how to generate 100% synthetic video. We don't even know where to begin. No one knows even roughly what the final techniques might look like.

Think about how integral a good artist is. Every rendering pipeline in the world is built for artist flexibility. When a talented team of artists feel empowered by the tools you write for them, they end up producing a different kind of movie altogether. It's not a matter of degree. The reason movies look incredible is because artists mastered the tools we make for them. That's their role, and this is ours. Both halves are crucial.

Yet what does that imply? Imagine we invent a program that produces perfectly real video. People think it looks like a nature documentary. Now think about everything an artist does in a modern pipeline: they decide which shaders to use. Which materials to apply, and to what. The base color of everything. The shape and the animation. They arbitrary select the physics. When grass changes color from green to brown, it's because the atoms they're made of are changing -- everything that makes light bounce off grass in a way that looks real, those are the parameters that artists change "till it looks good." It's arbitrary. It makes no sense to say with a straight face that we've created a "physically based renderer" when the artists have complete authority to break every assumption and piece of data that those physics simulations were modeled from.

The fact that they have so much flexibility is a strong hint that we are very far from mastering this. If artists' jobs were mostly identical to a set designer's job -- placing lights, arranging the scene -- then our renderer must look so real that it may as well be reality, right? If it looked perfectly real, there would be no reason to change it, except as a stylistic choice (which is fine, but it's unrelated to our goals).

Now, people will immediately try to convince you that there are engines out there that work that way. Artists are mostly set designers, they say. But all you have to do is look. Take a clip from whatever movie they produced, and put it side by side with a nature video. Then put it next to the most visually cutting-edge movie you can think of. An honest assessment will show a striking difference.

Lack of flexibility kills the art. The flexibility is the only technique we have. The fact that you can get really talented artists together and give them highly advanced tools, and they end up spitting out stuff that looks real -- it's not inherently obvious that we should've been able to invent those techniques! The fact that it's possible at all is amazing. When graphics programmers believe in the ideology of physically-based rendering, they become slaves to hubris. They start thinking it's reasonable to take away the only tools that work.

Ask yourself this: When an artist is free to flex all the parameters until it looks real, what's going on there? What does that mean, in a fundamental sense?

It's a deep question, and I still haven't come up with a complete answer. But I think it's reasonable to say that artists attempt to make the output on the screen match the output that a video camera would have recorded, if the scene were real. Yes, they make a few stylistic tweaks, but all of it still looks awesome. That's why people pay to experience it. It's partly why Star Wars was such a hit. It was believable.

And that, my friend, is the real question. Asking "Do we know how to make something look real, if only we spent enough money or CPU power on it?" turns out not to make any sense. Counterintuitive, yet true. People care about making movies or manipulating images in photoshop or making games look awesome. They don't care about wasting time trying to coax the computer into generating video that can fool an audience -- they already have a thousand techniques for fooling them! Why generate it when you can mix in actual video from the real world?

As strange is it sounds, I think the full answer is: no one realizes we have no idea how to generate video of complex scenes indistinguishable from reality in a double-blind test because there's no money in it. Not yet. If you happen to invent it, your company might make a million dollars. But you're more likely to lose a million by trying to achieve that objective.

What about scientists? Surely some of them must have spent their lives trying to answer such a deep and fundamental mystery?

Yes and no. There is a lot of impressive work out there, but scientists are mainly concerned about getting published. Their careers are at stake. If you don't publish, you can't get funding, and your impact comes to an end. And the problem is ambiguous: what does it mean to publish a paper related to the idea that people don't know how to generate synthetic images that look real? Everyone already knows that! You can't write a paper on that. The best you can do is try to come up with a paper about an incremental improvement.

And that's exactly what we see. It's all we see. Negative results in science are mostly discarded -- much of the time, we simply don't hear about them. I am speculating, but I think this would be even worse in color science: it's not very prestigious work. When you run an experiment to validate the CIE model and end up with wildly different answers, what do you do? As a scientist with a deadline that may literally kill your career, how likely are you to chase down this mystery? Or to have the freedom to suddenly pivot, and to make the paper about that?

It felt strange to realize no one knows how to make 100% synthetic video look real. It's like sinking up to your neck in quicksand: an inescapable conclusion, and consequences people would rather not dwell on.

Focus on the data. That's the key. Not opinions, not what the professionals believe, but data -- hard answers, obtained from careful experiment with a large sample size -- you arrive at some very unexpected truths.

It's hard to know what to even do with the information. What do you even say? I would've dismissed this at 23. "What are the chances that everyone in the world is being sent to college to learn the wrong techniques? And what about all the published research? The guy who inspired me to become a graphics programmer worked so hard on his graphics engine. He spent years thinking about it. You're saying he has no idea what he's doing, and that all the techniques are fundamentally flawed? That they're not even kinda-sorta close?"

All I can say is, look at the data. Pretend you're piloting a plane in complete darkness. You either trust your instruments -- your carefully-designed experiments -- or you don't.