Fresh Angle to Perceiving Color

A well-trained eye can experience color to the full extent. Immediately spot if something works for the image (or not). Though, can anyone become such an artist? Let’s learn how to perceive colors in the 3d rendering process today!

By COMMONPOINT / Jan 01, 2022 / 18min READ



Common Knowledge

How can I master color grading? Can I learn to see the natural colors and have a “skilled eye?” What can I do if I just “don’t see it?” It seems challenging to understand color or even talk about it. But that’s not as difficult as you might think. Like anything else, you can train your eye through practice, no doubt. But hoping to get that “AHA” moment by accident is not the smart way to do it. Let’s start with an analogy.


Working with colors is pretty much like cooking. You can “taste” your colors one by one. As you add more and more ingredients, you can check their flavor and evaluate how they work together. Though, don’t expect to make a great dish when you throw everything at once without even tasting it.

This article will teach you to start cooking with color properly. We’ll introduce essential ingredients and their taste in different rendering stages. You’ll learn what “natural” colors mean and how to perceive them. Make calculated decisions about color, and be able to express your thoughts effortlessly. Over time, you’ll become more confident in this field and eventually be playful with color. You won’t become a “master chef of colors” in one day, but hopefully, this article will push you to get there.

Glossary

First and foremost, your image’s colors are the outcome of design and composition. You can make the colors look natural, but still, it may feel off if the composition has issues. We need to point that out since we believe the composition has the most impact on the overall feeling of the image. Assuming your image grabs attention at the right point, has a good sense of depth, and isn’t cluttered - let’s focus on the color itself. We will start with color vocabulary to pinpoint what we’re looking at. Check the example below to see the hidden color concepts, even though they might not seem 100% clear at the moment.



You’ll be able to deconstruct any image you like and evaluate the colors inside it. Having the tools to articulate your thoughts and what you’re looking at helps a lot. What is perceived lightness? Do my hues match the memory colors? Are those shadows inky or perhaps compressed too much? Those questions might seem weird for now, but they will help you decide if you’re on the right path with colors. We’ll show you the border between the technical and artistic approaches to color. It’s the quickest way to develop a “skilled eye.” So wait no more and start looking at the colors from a fresh angle!

Follow The Light

Our eyes can perceive reality purely by lightness. Absent color, we can identify objects, get a sense of depth, and even weather conditions. So the first step of developing a skilled eye is to understand how lightness works itself. Let’s start with desaturating the image and getting used to watching our work in black and white. In the following chapters, we’ll analyze it from different angles and check some technical things. For starters, a small question: Would you consider the images below to feel “natural?” Could you explain why?


The view outside is brighter than the ceiling lamp, which is brighter than the rest of the room. There’s a lightness hierarchy that makes it seems natural. The Sun will always be brighter than the sky, and the midday sky (even overcast) will always be brighter than artificial lighting. Furthermore, the reflection of the light source will never be brighter than the light source itself. It might sound trivial, but it is easy to disturb it with aggressive relighting or postproduction. Train your eye to spot any errors in those areas. You will increase the naturalness of the colors little by little, which this article will be all about.

“To check values in Corona Renderer, you can right-click on frame buffer and check RGB values, compare any points to see if they are too bright/dark with each other”

Don’t Lose Details

The next thing that distinguishes a natural, commercial look is preserving details. We essentially want to keep the most nuance from textures and materials. Unfortunately, we can lose them due to heavy/poor color grading and being unaware of the simple fact. There’s an effect called color compression, which essentially means squeezing colors closer to each other - becoming an area of the same color without any detail. You can observe it in any part of your image. However, it mostly happens in the deepest shadows and brightest highlights:


Crushing

Blowing Out

You can easily spot it when the effect is exaggerated. Though, it’s more challenging when you’re in the middle of rendering and lack perspective. The natural look has nuances between the colors, so always keep that in mind. Ask yourself: “Did I go overboard with color grading?” It usually happens when we add too much contrast or curve adjustments to the image. Also, it could result from applying luts, so be careful about that too. Speaking about luts. There’s an interesting color behavior that often happens if you use them:


Raising Blacks

Lowering Whites

It’s essentially raising the deepest shadows, giving that muddy gray, almost inky shadows, or lowering the highlights, making them look flat and muted. The latter can happen if you apply too much highlight compression in Corona Renderer. It’s not necessarily a bad thing, but it drives you away from a natural look. It gives a cinematic feeling, but you can easily go too far. We’d encourage you to put it aside until having a solid color foundation. All in all, be careful anytime you apply color operations while rendering. Preserve details as long as possible. You can always color grade in post-production, but you need that information first. This way, you can apply it to areas that really need it, which we will discuss in the next chapter.


Perceived Lightness

We learned about potential issues that might pop up. Let’s dive a bit deeper, assuming our details are intact. The next concept is the most critical part of perceiving lightness before jumping to color. It will get a bit technical but bear with us. We will split our image into three different areas. We’ll try to guess where the deep shadows end, and the bright highlights start. We’ll be left with three distinct areas, naming them blacks, midtones, and whites.

We drew a shape around them to be 100% sure what areas are we looking at. You can notice how dark the blacks are (0-10%) and how bright the whites are (75%-91%). That set of values gives a natural feel and a proper sense of lightness. It might sound fancy, but we’re trying to find how bright and dark things should be; it’s all it is. Every image will have different levels that make it look natural, and we need to find them. Obviously, using a reference is the best way to do it. Just place an image next to your work, and with a few basic adjustments, you can perfectly match it, like so:


Perceive Lightness Adjustment

How to use PureRef (Chapter 6-8)


It's that simple. You’ll “borrow” white/black levels from a reference. You’ll eye-ball them and roughly adjust them. Sometimes, the image might feel off, and simply raising the blacks will help a ton. Other times, you’ll need to lower the whites because everything is just too bright. Those black and white levels will anchor the perceived lightness in your image. Then you can play with midtones however you like, add strong contrast or leave it flat. Chances are, it will still look natural because midtones allow you to have great creative freedom.


Color

Black & White

Working with those three areas gives you a solid foundation to check if the lightness is on the right path. It’s impossible to find an exact point where one starts and the other ends, but you don’t need to. Be mindful of them and try not to be wrong by a lot. Pick a reference, and try to match it. Over time, you’ll know by heart how bright or dark anything should be. Chances are, thinking about it, you’ll improve your lighting skills as well.


Pure Looks Natural

We’re introducing color to the mix, and let’s start simple, just like before. We’re going to focus on white balance to make “white objects appear white.” You can keep in mind that “white reads pure,” and it gets us one step closer to the natural look. In the example below, we have a single image that has an adjusted, cold and warm balance. We’ll increase the saturation value to 100% and see what mostly happens with midtones and whites.


A skilled eye can immediately notice if the white balance is off, but it’s effortless to see an exaggerated effect. Colors can get warmer or colder, and you need to adjust them to match the lighting conditions. In our case, you’d expect to have warm areas from the sun and cold from the sky. During the night, we primarily expect colds from the environment (read more about it here, too.) At dawn, we anticipate warm colors all over the place. Slight shifts are okay, as long as you’re playing with the temperature only. But it gets problematic when tints get into your way. Notice how less natural it looks when we apply green or magenta:



In general, tints have a massive impact on the natural feel. We usually perceive the green/magenta as unnatural; one might say unpleasant, especially if not handled well. They’re challenging to manage because you can easily go too far. Notice if there’s too much green/magenta anytime you play with RGB curves, tints, or apply luts. Just like inky shadows and muted highlights, adding tints is an artistic effect and can work, but it’s driving you away from the natural colors.

Don’t worry if you feel that the concepts are stacking up. We’ll summarize all of it nicely by the end of the article.


Memory Colors

Now, we’re going to take a closer look at colors. We’ll assess the hues in this chapter and saturation in the next one. By hues, we simply mean whether it’s red, blue, green, etc. (the classification on the light spectrum.) Now, bearing that in mind, the next concept is pretty straightforward and very handy. Some colors are more important than others. They ought to look like they are “supposed to,” and you don’t have too much creative freedom with them. Those are highly familiar objects, and among them are 3 of the most important ones - greenery, sky, and the skin. “We share a common understanding of specific colors.”


Put in extra care and effort whenever they appear. Nailing down those colors will greatly improve the natural feeling of the image. Find an image that has similar lighting conditions and try to match it. Even though there’s no perfect hue that works in every possible scenario, we’ll try to make a calculated decision about them. Greenery will vary between green-yellow and green-blue. The sky will fall between blue-green and blue-magenta. By analyzing more images, you’ll find a sweet spot that simply works. We did a small test ourselves and put together many different sky gradients. The test showed a preference of sky colors, right between cyan and blue color:


Again, you need to help yourself with references; it’s the best way. Compare the colors and train your eye. It’s free. Just ask yourself, isn’t the sky too green? Isn’t the greenery too yellow? Fix the materials to match the memory colors or adjust them in post-production. It’s a low-effort thing that hugely impacts the natural look. We also elaborated more on the sky and foliage in articles here and here, so definitely check that out. What about the saturation, then? Well...


Saturation is Merciful

Well, that sounds interesting, isn’t it? Don’t worry; you don’t need to beg for mercy :) All we mean is that saturation gives great creative freedom. You can go crazy with saturation, and it can still look good. You can increase it to 20-30% to have a vivid and natural look. You can keep it low to give a painterly and subdued feeling. There’s no right or wrong answer. Check the examples below, how vastly different they are in terms of saturation.


There’s one caveat, though. You can have great creative freedom with your saturation as long as your hues are spot on. If something goes wrong with high saturation, it might be due to bad memory colors or unpleasant green/magenta tints. The last tip we might add is to keep the strong saturation within your midtones. The colorful blacks and whites don’t look natural. So the best way to add it is at the last step of post-production. To target specific areas, you can use Hue/Saturation or Selective Color Adjustment in Photoshop.

Lightness vs. Colors

We have most pieces of the puzzle. Many concepts to help you put the colors on the right path, especially if you haven’t analyzed the technical side of it before. We will introduce one more color property that is obvious, but you might forget about it while doing heavy color grading. Lightness (value), hue, and saturation are tightly connected. If you change the lightness - you affect the hue and saturation. The color will literally change from blue to blue-green when you increase the lightness a lot. Just like in the example below, check the difference between hues in the left upper corner and bottom right:


It is essential to understand that color operations affect each other. Strong contrast or heavy curve adjustment can shift memory colors. Also, increasing saturation or changing hues will affect the perceived lightness. It’s how the colors work, and we need to be aware of it. You shouldn’t worry too much about it, as long as you nail down the perceived lightness first and proceed with colors next. Let’s put it all together and make some final tweaks in the last step.

Fine-Tuning and harmony

At this stage, we should have a decent image. We have plenty of details, memory colors are spot on, and the perceived lightness feels natural. It might seem too simple, but yeah, it is when it clicks. Until then, put the extra effort into fixing issues we laid down. Don’t worry if it’s hard to nail all of them at the same time, but you’ll get there eventually. Help yourself with a ton of references, train your eye, be smart about it. With such an image, you can do one last thing in post-production:

Simplify your color palette

Narrow down your color palette if you have too many colors at the same time. It’s tough to manage colors if there are greens, blues, yellows, purples, and whatnot. Target specific areas, use Hue/Saturation or Selective Color to tone down some colors. It’s very fast and can improve your image’s naturalness and overall visual impact. If, however, you must incorporate all those different hues in your image, make sure to isolate them from each other properly. For instance, you shouldn't have your vegetation spanning across the entire spectrum from green-yellow to green-blue. It's better to keep all of it precisely in one hue. This way, you'll be able to bring some more order and balance, and it will help you prevent a messy appearance.

So yeah, let’s summarize all we learned today! How should a CG artist look at colors, and what to keep in mind? Let’s go!

Summary

We make multiple decisions at once in day-to-day work, so it’s hard to take a minute and train your eye. For that reason, we’ll help you focus on the right things at the right time. We’ve put a list of everything we have covered so far, so you want to practice your eye smarter. We believe it’s a solid foundation to understand colors on a deeper level. Like anything, it involves practice, but you’ll get there one step at a time. So here it is:

Use as many references as possible. Don’t fully trust your old instincts if you want to reprogram your eye. Be open to change, ask others if you’re doing a better job, and let them guide you. Over time, it’ll naturally grow to your workflow, and you won’t need to follow each step. The best part of it is you’ll be able to diagnose problems and help others. If you wish to share your color philosophy, we’d love to hear from you (hello@thecommonpoint.com). It’s such a fascinating subject that seems to be an endless exploration. We will dive deeper into making your color palettes, working with luts, and stylizing your images one day. But we hope this gives you a head start to perceiving natural colors, training your eye, and building that solid foundation to see and talk about color.

Artur: “One thing I would strongly encourage you to do is to talk to people about color. Ask questions, share difficulties, let others make decisions for you. You would be amazed how much you can learn simply by listening to people and applying what they suggest.”

Trust Your Gear

We’re a big advocate of having a decent/semi-decent display that is well-calibrated. We’d say it’s essential to understand colors and push your grading game even higher. Why, though? Isn’t everyone consuming the work on small and cheap displays anyway? Well, perhaps, but that doesn’t matter. We’d love to give you the two most powerful arguments for doing so. First one: You need to have trust in colors. You should see what’s real and don’t want your display to play tricks on you. There might be shifted white balance, and you wouldn’t even know about it.

Sandesh Shewale: "If your input is LESS then your output is LESS too."

The second reason is: You want to export as accurate colors as possible. If your viewer has a broken display, it will be off anyway. But it will get even worse if you make unwanted grading. The mistakes will multiply, taking you even further away from what you intended in the first place. We understand it gets expensive, but you should consider it before working for higher-profile clients. Also, you can double-check your colors on various displays and send your work to friends. We often check our colors on the iPad (wider gamut) and consumer-level display (narrower gamut) before sending it over to the client. You can pick up tons of things while watching your work on different screens.

Conclusion

A “skilled eye” is extremely valuable in a creative industry, so it should be very high on your priority list. You can definitely get there, being smart and efficient about it along the way. So, next time you scroll through your creative feed, start analyzing the images. You’d be surprised how many of them lack the fundamentals you know now. Identifying problems will be the first step of improving as an artist. Is perceived lightness wide or flat? Is there heavy compression, or perhaps the memory colors are off? We hope those questions make more sense now and allow you to look at color from a fresh angle!

Bartek: "Color is a complex subject that is pretty hard to dissect. For me, it is mostly because of how smoothly it connects with all other aspects of an image. You start speaking about colors, and suddenly you find yourself talking about composition or shader building. It is hard to define clean limits, and thus it quickly feels overwhelming. It might be one of the reasons why color is often treated as that totally subjective component of a personal style. I believe it is pretty harmful labeling, and sooner or later, we need to learn to talk about colors to become conscious creators.

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