monika zagrobelna - improve your artwork by learning to see light and shadow
DESCRIPTIONLearning to See Light and Shadow
Improve Your Artwork by Learning to See Light and Shadow Monika Zagrobelna
It's very common for painting tutorials to treat light as an addition to the picture, an atmosphere-maker. We can easily get the impression that the object has a universal form, and then with proper lighting we can change the mood of the picture. The truth is without light there would be nothing to paint! Until you realize that, you're shooting blind.
In the first tutorial of this short series, I'll introduce you to the art of seeing light, shadows, reflections and edges.
How Can We See?
As an artist, have you ever tried to answer this question? If not, that's a big mistake. Everything you draw is a representation of seeing, just like the laws of physics are a representation of real processes. There's even more to itwhat we draw is not reality, or an objective image of reality. It's an image created by your brain, an interpretation of signals caught by your eyes. Therefore, the world as we see it is only an interpretation of reality, one of manyand not the truest or most perfect of them all. Only good enough for our species to survive.
Why am I talking about this in a painting tutorial? Painting itself is an art of darkening, lightening and coloring certain parts of paper (or screen) to create an illusion of looking at something real. In other words, an artist tries to recreate an image that could be created by our brain (it makes it easy for us, since we think in patternswe tend to look for familiar shapes in abstract pictures).
If a picture is similar to what we see in our minds, we say it's realistic. It may be realistic despite not having any recognizable shapes or outlinesall you need are a few patches of color, light and shadow to bring something familiar to mind. Here's a good example of this effect:
Winter in the forest by Piotr Olech
To create a convincing picture similar to one created by the brain, first you need to know how the brain does it. When reading this article you'll find most of the processes quite obvious, but you may be surprised at how closely science can relate to painting. We tend to see optics as a part of physics, and painting as a part of metaphysical art, but that's a mistakeart is a reflection of reality seen through our eyes. In order to imitate reality, first you need to know what our minds find real.
So What Is Seeing?
Let's go back to the fundamentals of optics. A light ray hits an object and bounces to your eye. Then the signal is processed by your brain and the image is created. That's pretty well-known, right? But do you realize all the consequences that stem from that process?
Here comes the first, the most important rule of painting: light is the only thing we can see. It's not an object, not a color, not a perspective, not a shape. We can see only light rays, reflected from a surface, disturbed by the properties of the surface and our eyes. The final image in our head, one frame of the never-ending video, is a set of all the rays hitting our retina at that one moment. This image can be disturbed by differences between the properties of every rayevery one of them comes from a different direction, distance, and they may have hit a lot of objects before hitting your eye last.
That's exactly what we're doing when paintingwe imitate rays hitting different surfaces (color, consistency, gloss), the distance between them (the amount of diffuse color, contrast, edges, perspective), and most certainly we don't draw things that don't reflect or emit anything to our eyes. If you "add light" after the picture is almost done, you're doing it wrongeverything on your painting is light.
What is Shadow?
To put it simply, shadow is an area untouched by direct light. When you're staying in shadow, you're not able to see the source of light. That's obvious, right?
The length of shadow can be easily calculated by drawing the rays:
Drawing shadows may be a little tricky though. Let's take a look at this situation. We've got an object and a big light source. Intuitively, this is how we draw the shadow:
But wait, this shadow is actually cast just by a single point on the light source! What if we choose some other point?
As we can see, only point light creates a sharp, easily defined shadow. When the light source is bigger (more scattered), the shadow gains a blurry, gradient edge.
The phenomenon I've just explained is responsible for supposedly multiple shadows coming from a single light source too. This kind of shadow is more naturalthat's why pictures taken with flash look so sharp and odd.
Ok, but that was just a hypothetical example. Let's take a look at this process in practice. Here's my tablet pen stand, photographed on a sunny day. Can you see the weird double shadow? Let's take a closer look.
So, light comes from the left lower corner, roughly. The problem is it's not a point light, so we don't have the nice, sharp shadow that's the easiest and most intuitive to draw. Drawing rays like this doesn't help at all!
Let's try something different. According to what we've just learnt, a big, scattered light source is made of many point light sources. When we draw it like this, it makes much more sense:
To explain it more clearly, let's obscure some of the rays. See? If not for these scattered rays, we'd have a pretty normal shadow!
No Seeing Without Light
But wait, if light doesn't touch the area, how can we see something that is in shadow? How can we see anything on a cloudy day, when everything is in the shadow of the clouds? That's the result of diffused light. We'll talk more about diffused light throughout this tutorial.
Painting tutorials usually treat direct light and reflected light as something totally different. They may tell you there's a direct light that makes surfaces bright, and that reflected light may occur, giving a bit of light to the shadow area. You might have seen diagrams similar to the one below:
This isn't completely true, though. Basically everything you see is reflected light. If you see something, it's mostly because light has reflected from it. You can see direct light only if you're looking directly at the light source. So the diagram should look more like this:
But to make it even more correct, we need to bring in a few definitions. A light ray hitting a surface may behave in a few ways, depending on the kind of surface it is.
When a ray is reflected fully by the surface at the same angle, it's called a specular reflection.
If some of the light penetrates the surface, it may be reflected by its micro-structure, creating a disturbed angle resulting in a fuzzy image. This is called diffuse reflection.
Some of the light may be absorbed by the object. If an absorbed ray manages to get out, it's called transmitted light.
For now, let's focus on the diffuse and specular reflection only, since they are very important to painting.
If a surface is polished and has a proper, light-blocking micro-structure, a ray hitting it will be reflected at the same angle. Specular reflection creates a mirror effectnot only direct light is reflected perfectly, the same happens to the "indirect" rays (moving from the light source, bouncing off an object, and hitting a surface surface). An almost perfect surface for full specular reflection is, of course, a mirror, but some other materials give a good effect too (metal and water are examples of this).
While specular reflection creates a perfect image of the reflected object thanks to the correct angle, diffuse reflection is far more interesting. It's responsible for color (we're going to talk about this in more details in the next part of this series) and it lights up the object in a softer way. So, basically, it makes an object visible without burning your eyes out.
Materials have various factors of reflection. Most of them will diffuse (and absorb) a huge part of the light, reflecting only a small part as specular. As you probably already guessed, glossy surfaces have a higher factor of specular reflection than matte ones. If we look at the previous illustration once again, we can create a more correct diagram for it:
When looking at that image, you may be under the impression that there's only one point on a glossy surface where specular reflection occurs. That's not completely true. It occurs wherever light hits the surface, but there's only one specular ray hitting your eyes at a time.
Here's a simple experiment you can do. Create a light source (use your phone, or a lamp) and place it so that it lights up a shiny surface from above and creates a reflection. It doesn't need to be a very strong or vivid reflection, just make sure you can see it. Now take a step back, looking at the reflection the whole time. Can you see how it moved? The closer to the light source you are, the more acute the angle. Seeing the reflection directly under the light source is impossible, unless you are the light source.
What does this have to do with painting? Well, here comes rule number two. The position of the observer influences the shading. The light source can be fixed, the object may be fixed, but every observer will see it a bit differently. It's obvious when we think about perspective, but we rarely think of lighting this way. In all honesty do you ever think about the observer when setting the lighting?
As a curiosity: have you ever wondered why we tend to paint a white grid on a glossy object? Now you should be able to answer this question yourself. Also, now you know how glitter works!
Value Is the Amount of Seeing
Value is the amount of information brought with light. We're not talking about color yetfor now, our rays can be only darker or lighter. 0% value (brightness) is no information. It doesn't mean the object is blackwe just don't know anything about it and perceive it as black. 100% value is the maximum amount of information we can get at a time. Some objects reflect a lot of information to us and they appear bright to us, while others absorb a big part of the light hitting them and don't reflect too muchthose seem dark. And what do objects look like without light? Hint: they don't.
This interpretation will help us understand contrast. Contrast is defined as a difference between pointsthe bigger the distance between them on a value scale, the stronger the contrast. All right, but where do different values come from?
Colors of Gray: Contrast
Take a look at the illustration below. The observer gets x of information from A, and y from B. As you can see, x is much longer than y (x=3y). The bigger the distance, the bigger information loss, so in the first situation we can see B as correctly illuminated, while A is a bit duller.
The other situation is different. Here x and y look roughly the same (x=1.3y), so they're going to bring a similar (small) amount of information.
The result from the observer's view would look like this:
But wait, why are the closer objects dark and the distant ones light? The lighter, the more information, right? And we've just said the information is being lost as the distance grows.
We need to explain that loss. Why can the light from very, very distant stars come to your eyes without larger disruptions, but buildings a few miles away lose details and contrast? It's all about atmosphere. You see a thinner layer of air when looking up than when looking ahead, and the air is full of particles. The rays traveling to your eyes at a big distance hit these particles and lose a bit of information. At the same time, these particles may reflect something else to your eyes - mainly blue of the sky. In the end, you'll see a leftovers of the original signal mixed with impurities - it looks bright, but it brings little original information and a lot of noise.
Let's come back to our illustration. If we draw the loss of information with gradient, it nicely shows why close objects are allowed to look dark. Also, it explains the visible value difference between close objects, and similarity of value of distant objects. Now it's obvious why objects lose contrast with distance!
There's even more to it. Our brain perceives depth by calculating the difference between images seen by each eye, and with distance this difference becomes less and less significant. In the end, distant objects seem flat, and close ones are more 3D.
Edges (lines) are a side effect of a proper lighting on the picture. If your painting looks flat and you need to draw outlines to bring attention to the shapes, you're doing it wrong. Lines should appear on their own as borders between two different values, so they're based fully on contrast.
If you use the same value for two objects, you'll make them look merged.
The Art of Shading
After all this theoretical stuff you should have pretty good knowledge on what's actually happening when you paint. Let's talk about practice now.
The biggest issue with shading is that it's about creating a 3D effect on a flat sheet of paper. However, it's no different from drawing in 3D! An artist can go pretty far avoiding this problem, focusing on a fully cartoon style, but eventually if they want to progress, they'll need to face their arch-enemy: perspective.
What does perspective have to do with shading? More than one could think. Perspective is a tool to draw 3D objects in 2D without making them look flat. Since they're 3D, light strikes them in various ways, creating highlights and shadows.
Let's try a little experiment. Try to shade the object below using the given light source:
It'll look something like this:
It looks pretty flat, doesn't it? More like a simple gradient put on a 2D surface.
Now try to shade this one:
Here's what your drawing should look like now:
Now that's a different story! The object looks 3D despite the simple, flat shades we've added. How does that work? The first object has one wall visible, so for the observer it is actually one flat wall, and nothing else. The other object has three walls, and we know 2D objects don't ever have three walls. The sketch itself looked 3D to us, so it was very easy to picture the parts that light can or can't touch.
So next time you prepare a sketch for your painting, don't draw it as lineart. We don't need lines, we need 3D shapes! Build your objects using figures in perspectivemake
the shapes show. If you define the shapes properly, not only will your object look 3D, but you'll find shading is suddenly surprisingly easy.
Once the basic, flat shading is done, you can refine it, but don't add any details before that point! Basic shading defines lighting and lets you keep everything consistent.
Let's take a look at the correct terminology when discussing light and shadow.
Full light is the area in front of light source. Highlight is a place where the specular reflection finds its way to your eyes. It is
the brightest point of the shape. Half light is a full light darkening gradually toward the terminator. Terminator is a virtual line between light and shadow. It can be sharp and clear
or soft and blurry. Core shadow is the area that faces away from the light source and is therefore
not illuminated by it. Reflected light is diffuse reflection hitting the core shadow. It is never brighter
than the full light. Cast shadow is the area blocked from the light source by the object.
Although it may seem obvious, the main lesson you need to take from this is: the stronger the light, the sharper the terminator. Therefore, a sharp terminator is an indicator of some kind of artificial light source. To avoid it, always blur the area between light and shadow.
Once you've realized what seeing really is, photography doesn't seem so different from painting. Photographers know that it's light that makes a picture, and they can use it to change what they want to show. It's said that nowadays photos are too "photoshopped", but the truth is a photographer rarely takes a picture of something
as-is. They know how light works and they use it to create a more attractive picture, and that's mainly why an expensive camera doesn't automatically make one a professional photographer.
You can take two different approaches when setting lighting for your picture:
Imitate nature, creating the light as it usually occurs. "Sculpt with light", creating a conducive light to show something as attractively
The first approach will help you create a realistic effect, while the other one is a way to enhance nature. It's like a warrior in old, dented armor with a club in hand versus a beautiful elf-girl in shiny, impractical armor, wielding a magic weapon. It's easy to say which is real, but which is more attractive and eye-catching? The decision is for you to take, but remember to always take it before painting, not during, or only because something went wrong.
To clarify, it's about style of lighting, not about subject. You can use realistic lighting for a unicorn or a dragon, and you can as well ennoble the weary warrior. Sculpting with light is about putting the light sources exactly where they should be to emphasize the outlines of muscles or the shine of the armor. In nature it rarely works this way, and usually all objects of the scene look like a whole. Therefore, I'd suggest the natural method for landscapes and the enhancing method for characters, but by mixing both methods you can create even better effects.
Realistic shading can be learned from nature only. Don't use pictures of others or even photographs, because they can use "cheating" you won't even notice. Just look around, keeping in mind all you see is light. Locate the specular and diffuse reflection, observe shadows and create your own rules for it. However, you need to keep in mind that people pay more attention to the details of a photo or painting than they do to the general world around them. Images are easier to "absorb", since they engage only one sense, and can be focused on. The consequence is your pictures are going to be compared to other still images, not to reality.
If you choose the other approach, there's a trick I can show you. Photographers call it three-point lighting, although you can also use a two-point method for a more natural effect.
Let's start with a simple object. This teddy bear has been put in a space with a distant, weak light.
Let's put a strong light source pointed directly at the bear's front side. Use it to add in primary lights and shadows, then blend the shades. This strong, direct light source is known as a key light.
To drag the teddy bear out of the darkness, let's put it on an infinite ground. The ground is affected by the light source and a cast shadow appears. Since rays hitting the ground are diffuse, they are reflected at the teddy bear too. There's also a thin layer of blackness under the bearit's called crevice shadow and it occurs every time the object isn't merged into the ground.
Let's put our teddy bear in the corner of a room. This time, light rays hit the walls too and we've got a lot of diffuse reflection everywhere. Therefore, the darkest areas of the teddy bear get a bit of illumination (not as bright as from the direct light, though) and the contrast is balanced.
What if we remove the walls and add some thick atmosphere instead? Light is going to be scattered, and we'll still have a lot of diffuse reflection. Soft light or diffuse reflection coming from the left or right of the key light is called fill light and is used to fill shadows which are too dark. If you stop here, you've created two-point lighting, which often occurs in nature, where the sun acts as a key light and diffuse reflection from the sky creates the fill light.
We can add the third "point" to it, the rim light. It's a back light, usually placed so that the object blocks most of the light from reaching the viewer's eyes. Rays avoiding the object create a clear edge, distinguishing the object from its background.
Rim light doesn't necessarily need to create a thin "rim". Its function is just to make a rim pop out, so you can use any direction and sharpness you need.
One more tip: even if you're not drawing a background, paint the object as if it had some environment. When painting digitally, you can even create a kind of background-dummy on a different layer, with messy patches of light and shadow that will help you calculate what should affect the object!
by 17 Monika Zagrobelna Apr 2014
Color Fundamentals: Shading
by 28 Monika Zagrobelna May 2014
We tend to see color as an attribute of every material thing, and light as a factor that can change it. Tomato is red, grass is green, and light can only add a tint or shade to it, right...? Wrong.
Color doesn't exist universally - it's the effect of our vision mechanism, fueled by light. No light, no color, and you can notice this easily when it's dark. It's not that darkness "covers" the colors - it's light what creates them! If it sounds revolutionary to you, keep on reading - there's no more important thing to understand for an artist. Also, make sure to read the first article of the series before trying this one - it's a great introduction to shading.
What is Color?
Let's take a little physics revision. Don't worry, I'll make it as simple as possible! Some objects are able to emit radiation, what that means is they throw a bunch of particles (or waves) in various directions. Light is a kind of radiation, and every light source emits photons.
Photons are waves combined of various wavelengths (here x, y, x).
We're going to call the way the photons fly between the light source and a particular direction a ray.
Those were a couple of facts. But what happens when a human factor comes in? There's a lot of radiation everywhere around us, but our eyes are specialized to react to only a particular range of wavelengths. For example, we don't see heat until its wavelength comes into that range (red-hot metal suddenly becomes a light source). This part of electromagnetic radiation we can see is called visible light, and is commonly known as just light.
We've discussed it shortly in the first article of this series, but let's add a bit of detail now. There are two kinds of photoreceptor cells in our eyes: cones and rods. When a ray hits them, they react and transfer some information to the brain.
Rods are very light-sensitive and are responsible for night vision, seeing movement and forms. Cones, on the other hand, are much more interesting for us. They are able to separate the wave into particular wavelengths, that the brain interprets (roughly) as red (long), green (medium) and blue (short). Depending on what wavelengths the ray consists of, we perceive a color mixed of these three.
But where do various wavelengths come from, if they are all brought by the same light source? Most of rays hit some object on their way, and then they're being reflected somewhere else (for example, to your eye). Usually the object they hit doesn't reflect them perfectly like a mirror. Some of the wavelengths are being absorbed by the object and they never reach your eye. As a result, we receive only a part of the original ray from that object. These remains of the ray are then interpreted by your brain as the color of the object. Different colors come from different absorbing and reflecting properties of materials.
You probably wonder what it all has to do with color in painting. After all, we only paint with colors, we don't create them physically! I'm sure everything will become clear in a second.
Hue, Saturation, Brightness
Is there something more confusing than this? Our intuition tells us what hue, saturation and brightness is, but when it comes to painting, it's hard to guess how to use it. Hue is, well, color, right? Saturation is a level of vividness... and brightness tells us if something is dark or bright. But it only makes sense as long as you talk about a finished painting, and it's much harder to guess where to put it all when you do it yourself. However, all we need is to understand where all these values actually come from!
The Definition of Hue
Hue is a "type" of color. Red, purple, olive, crimson are all hues. They're based on the mechanism we've just talked over - the reflected wavelengths, mixed in various proportions, create a final color interpreted by brain. Therefore, putting it simply, hue is based on "the color of the object". An interesting fact: silver, gold or brown aren't hues. Silver is shiny gray, gold is shiny yellow, and brown is dark or unsaturated orange.
No matter how many names we invent for the hues, all of them base on red, green and blue. The further on the color wheel you are from any of them, the more "original" color you'll get. For example, 50% red + 50% green gives yellow, but change this proportion just a little bit and you'll see a greenish or reddish tint.
There's no greater or lesser hue, being put on a wheel they're all equal. Hence we describe them by degrees instead of a percent value.
The Definition of Saturation
Hue doesn't mean color (at least not formally). All the circles below have the same hue, the same exact position on the color wheel (the same brightness too!). So why do we perceive them as different colors?
The common definition of saturation is how much white there is in the color. But wait, wasn't that about brightness? You want brighter color, you make it whiter... But that would make darker areas more saturated. It's so confusing, isn't it? That's why we need more explanation.
Saturation is the dominance of color. The three samples below have the same brightness and hue. The only thing that changes is the proportion between the components. We're not "adding white" - we're reducing the distance between the components, so none of them stands out.
As you can guess, when there's no difference between the components, we've got no saturation, which gives us white (we don't include brightness yet).
The Definition of Brightness
For our needs we can treat brightness as synonymous with value from the previous article. It defines the maximum of a value our eyes can perceive. There's no more blue than 100% blue, just like there's nothing brighter than 100% white.
The bars can't be filled over the maximum:
And, obviously, black comes from the lack of information.
An interesting fact: when it's dark, our cone cells get a little information, what makes us a bit color-blind. At this time rod cells, sensible to any light, will take over. However, since they're the most sensible to green-blue light, they'll make any green-blue object look brighter. It's called the Purkinje effect.
Despite having a certain, absolute brightness, every color has another property, luminance. While brightness tells us how much of color there is in the color, some of hues appear brighter to us - even when they're all 100% bright. Luminance is about how bright color is relative to white.
When we turn 100% bright primary colors to grayscale, their brightness suddenly drops. They still make white, but blue turns out to be very, very dark, and green the brightest of them all. It comes from individual sensitiveness of every cone, and that's why we perceive yellow (bright red + very bright green) as the brightest of colors, or why cyan (dark blue + very bright green) is sometimes called light blue. Luminance is important when you start your picture in grayscale - for example, yellow needs a brighter base than other colors of the same absolute brightness.
It's still a bit confusing, though. In reality we don't build the colors carefully, it would take too long! Fortunately, hue, saturation and brightness can be combined into a very useful tool. Take a look at the scheme below - you can notice there's a clear relation between colors. Why not use it?
If you're a digital painter, these should look familiar to you. It's a way of combining hue, saturation and brightness into one, consistent model called HSB. How does it work?
Once you've known what hue, saturation and brightness are, it's easy to locate them on the model. Hue wheel (or a bar, it doesn't matter) is independent and superior to SB square/triangle. Every hue possesses a range of saturation and brightness, and these two values are bound to each other. Together they define "richness" or "colorfulness" of a particular hue.
SB model can be divided into areas of different properties. If you learn to optically choose a proper color, you won't need to know anything about certain values of saturation or brightness - it's very helpful for spontaneous, fast painting.
While the square is much more intuitive, I personally prefer the triangle. It lets me control "richness" at a whole, not severally saturation and brightness (I've got separate sliders for that!). If you're like me and feel Photoshop could use a nice color wheel being opened all the time, check out this amazing, free plugin by Len White.
CMY and RGB
But what about traditional painters? They don't have a handy color wheel with neat sliders. How can you change a hue, saturation or brightness of a pigment?
First, let's think what's the difference between digital and traditional painting. They both use colors, right? The problem is digital painting uses colorful light sources, creating most perfect colors possible and shooting them right into our eyes, while in traditional painting we're limited to light reflected from a pigment. It's like using a middleman between what's painted and what you actually see! We can debate what medium is more artistic, but there's no doubt that digital painting does better with our vision mechanism.
So, to paint traditionally we need pigments. They don't emit color themselves, and instead they absorb some of the light hitting them, reflecting the wavelengths compatible with their names. For example, red paint absorb green and blue, reflecting only red.
The problem is we're not able to create perfect pigments reflecting the light exactly as it would be emitted, e.g. a pigment stimulating the "blue" cone only. CMY system is a kind of compromise: cyan doesn't reflect red, magenta doesn't reflect green, and yellow doesn't reflect blue. So, if we want to stimulate "blue" cone, we need to mix cyan and magenta - this pigment will reflect as little red and green as possible. "K", black, is added to CMY since the components are not perfect and they don't create pure black when mixed in equal proportions.
RGB is additive - the more values you add, the brighter color you get. CMY is subtractive - the less values you add, the brighter the color.
Four Rules of Color Mixing
Rule 1 - Hue Mixing
By mixing two hues you get a hue from somewhere between them, according to proportion. It works for both additive and subtractive mixing.
Rule 2 - Complementary Hue Mixing
You probably heard of complementary colors. They are hues laying in opposite to each other on the wheel. The contrast between them (when they've got the same brightness) is as striking as between black and white. However, when they're mixed, they neutralize each other.
Mixing complementary hues gives neutrality (gray or grayish). Additive mixing of 100% bright complementary hues will return white, subtractive - black.
In subtractive method, adding a bit of complementary hue is the easiest way to precisely reduce saturation.
Rule 3 - Saturation Mixing
In both methods, proportions between components equalize when mixing, and in result saturation is reduced.
Rule 4 - Brightness Mixing
Additive mixing returns brighter color, and subtractive - darker than the lighter one of the components.
The tradition to divide the color wheel into warm and cold halves is very strong. We know that warm colors are active and friendly, while cold colors are passive and formal. Whole books could be written about psychology of color, but the problem is this is not an objective division. What's the warmest color? Red, yellow? Is purple warm or cold? And where exactly should this border line be?
Look at the picture below. These are all reds, theoretically warm all the way. So why some of them appear colder than others? It's about contrast. A color can't be warm or cold, only warmer or colder. The color wheel is so easy to divide visually, because all these colors are put together and easy to compare. Cut red out of it and it's no more warm or cold. It's just red.
So, how to create a warmer or colder color? Every hue on the wheel has a neighbor. These neighbors are always colder or warmer than our sample (check their neighbors too, if you're not sure). To create a colder version of the sample, slide into direction of cold neighbors (and vice versa).
The Basic Rules of Shading
About time, huh? Give me a moment and you'll see this lengthy introduction was necessary to understand the whole process. If you memorize the rules only, you limit
yourself to particular situations, but once you've understood where they come from, the sky is the limit!
The Local Color
The common base color, said not to be lighted by any light source, is called the local color. We already know an unlighted object can't have any color, so the better definition is a color not affected strongly by the light nor shadow. So a cherry's local color is red, even if it's illuminated with strong orange light on one side and reflected blue on the other. The local color should be the one you're starting your picture with.
What should be the saturation and brightness of the local color? The brightness is defined by imaginary scattered light that you start your scene with. To define the general brightness of the scene (the intensity of the scattered light) put your object on a white sheet. They're both illuminated by the same light, and the object can't be brighter than the white sheet under the same conditions.
The explanation is simple - the white sheet reflects 100% light. If the object was brighter than it, it would mean the object reflects more than 100% light (so it's fluorescing or emitting light itself). It's all about contrast, so the darker is your base lighting, the more striking light source you'll be able to add later.
What about saturation? While brightness is about intensity of light, saturation comes from proportion between its components. This proportion stays the same when the intensity of light is changing (with a little exception we'll talk about in a second). It's like adding more water with every teaspoon of sugar - the drink is not going to become any sweeter!
The Direct Light Source
Here's a quick reminder about light areas from the first article:
Let's start with a simple scene not illuminated by any well defined light. The ground is green, the ball is red, and the sky... doesn't matter at the moment. If the background is very far away, it doesn't affect our object. We chose the brightness and saturation, and for now, without no directional light, it looks flat, 2D. That's why we call it flat colors, and it's the easiest part of painting.
When the light source is presented, it floods all the scene. Its intensity - brightness - is the highest where the light has a direct contact with objects (full light, half light) and the lowest where it cannot reach (core shadow, cast shadow). The brighter the light, the darker the shadow. Our local color becomes the terminator.
To keep the ball from floating, we need to add crevice shadow - the area where no light can reach. This is the darkest area of the picture.
The problem is the scene still looks... fake. It's colorful, merry, as if it came from a children book. But something's wrong... If you've read the first article carefully, you may notice we used only diffuse reflection. Every single ray hitting the ball was partially absorbed, reflecting only red. Therefore, in the area of maximum brightness we've got 100% red and there's no way of changing it! This is very natural state for matte materials, and decreasing saturation to get a "brighter" red is a mistake.
If it's natural, why does it look fake? It's because fully matte materials are very rare in nature. Almost everything reflects at least a bit of specular reflection, and it doesn't need to be a high gloss - usually it's very soft and subtle. Change your position when looking at some object close to you - if its "colors" move along to your movement (even subtly!), they're the effect of specular reflection. The ones independent to your position come from diffuse reflection.
Specular reflection, as we've learned before, is a reflection of the light source. The stronger it is, the clearer the image of the light source appears on the object. The biggest role here plays the proportion between specular and diffuse properties of the material. High glossy objects usually have a thin layer of transparent, strongly specular material on them, so both kinds of reflection don't mix (third ball).
To put it straight, when decreasing the saturation of a bright area ("adding white" to it), you're not brightening it - you're adding gloss.
However, the balls above still look fake! (so many ways to paint fake colors, huh?). This time they look like taken from a 3D modeling exercise. This is because we used neutral white light that doesn't occur in nature either. Sunlight, before it can reach our eyes, needs to break through the layers of atmosphere. The previous article explained what happens here, so let's just add color to this mechanism.
Short and medium wavelengths are being scattered the most easily. The longer their way through atmosphere, the more of them stray and never reach your eyes (at least, not from initial direction). Therefore, a "white" ray becomes mostly red and green, and even in the highest point it has a bit of blue deficit - sunlight is warm.
So why would reflection of a warm light source be neutrally white? To avoid that fake 3D model effect, decrease the saturation and increase the temperature at the same time when adding warm gloss (no matter strong or subtle). As we noticed before, there are cold and warm reds, so it doesn't mean that a red surface becomes orange or yellow instantly!
It's important not to use gloss as a universal way to make the picture more attractive. When you feel you're getting closer to white, it means your object is shiny or wet. Think about it when painting skin!
The Indirect Light Sources
But what happens to all this blueness that gets scattered? It makes the sky blue, of course, but if we can see this bright blueness, it means it reaches our eyes - and not only our eyes. All the objects around get "touched" by this indirect light, and then it can be reflected to us too. It's not as bright as the direct sunlight, but it still makes the surface a bit brighter. Also, if it's not fully matte, the surface loses a bit of saturation and becomes colder (since our indirect light source is cold). Keep in mind that the direct light is always stronger than indirect one, so these two will never mix - indirect reflection can't cross the terminator line.
The most intense reflections are created by glossy surfaces, but matte ones, like our "ground", affect the objects too.
As we noticed in the previous article, contrast decreases with distance. But what about hue, saturation and brightness of the receding object? Well, it's a little bit more problematic. When the object recedes into background, the information from it is mixed with the light reflected from the sky, right? It means that:
Hue gradually changes temperature in the direction of the sky's hue; Brightness gradually grows until it reaches the value of the sky; Saturation is mixed with the noise, therefore it decreases. However, if the light
source is actually in the background (the foreground is dark), the saturation may increase gradually with coming close to it.
The clearer the atmosphere, the less this effect occurs. Respectively, when there's a lot of dust, smoke or humidity around, even close object change their properties drastically. The common trick of artists (and movie creators too!) is to render aerial perspective even in smaller scale, for example drawing one leg of a monster bluer, brighter and less saturated. For our brains it means it's further, and therefore a depth is achieved. However, keep in mind it also thickens the atmosphere - it will not work in clear air.
Color and Value
Proper coloring creates correct values, so to say, involuntarily. Beginners often start their pictures with values only to define them properly, but the truth is with the rules we've just learned you shouldn't have any problems with color painting. How can it be?
The initial brightness of the local colors sets an uniform brightness for all the scene;
Diffuse lights and shadows are as saturated as the local color - unsaturated shadows would look brighter as value!
The more gloss, the more value brightness; Indirect lights are never brighter than direct one, so they can't be confused
with main light source; The local color becomes a terminator, with shadows on one side and lights on
the other, what creates a proper contrast.
How to check if more lights or shadows should be added? It's a matter of contrast and you need to choose yourself which is the best for your picture's atmosphere. Generally, it's good to put your main object on three backgrounds: white, black and 50% gray. If it looks OK on every one of them, you're fine. Converting your picture to grayscale for a test is a good idea too.
Points to Remember
Highly saturated, bright colors are rare in nature - reserve them for flowers, birds and magic things;
Put lights on lights, never lights on shadows! If you want to put a light on a dark area, brighten it gradually;
If the shading looks too colorful, take a break, get some distance. There's a chance your eyes are just too focused on them after hours of work and the colors are actually OK. Rotating the picture or looking at it indirectly, in the mirror can help too;
Save pure white for highlights and 100% black for crevice shadows - overusing them drastically decreases their power.
No More Guessing!
Once you've realized that color is just a signal, a kind of information, it's so much easier to imitate the real world with your paintings. You don't need to memorize hundreds of rules - once you've understood the fundamentals, you can calculate reality with a great accuracy! Of course, don't treat them as a universal recipe for success - art is art, and sometimes you get the best effects when actually breaking the rules.
Stay tuned for the last article of the series, where I'll present you more tricks, such us multiple and colorful light sources, transparency, subsurface scattering, light emission and refraction, and show you what's the fuss about textures.
Improve Your Artwork by Learning to See Light and ShadowHow Can We See?So What Is Seeing?
What is Shadow?No Seeing Without LightValue Is the Amount of SeeingColors of Gray: Contrast
The Art of Shading3D IllusionTerminologyThree-point Lighting
Color Fundamentals: ShadingWhat is Color?Hue, Saturation, BrightnessThe Definition of HueThe Definition of SaturationThe Definition of BrightnessLuminance
CMY and RGBFour Rules of Color MixingRule 1 - Hue MixingRule 2 - Complementary Hue MixingRule 3 - Saturation MixingRule 4 - Brightness Mixing
Color TemperatureThe Basic Rules of ShadingThe Local ColorThe Direct Light SourceThe Indirect Light SourcesColor and ValuePoints to Remember
No More Guessing!