The colors and effects of light are one of the most complicated subjects because, to understand it well, we have to deal with facts of science (objectivity) at the same time as dealing with the artist's unique perception (which is quite subjective).
What we can do is learn from both fields, science and art - to ground our choices on scientific facts but also to include our personal tastes so that the light and color effects expressed have something of our own artistic expression.
In this article, I will share with you some notes and ideas that I have accumulated over the years. The idea is to offer a simpler introduction to a more advanced way of thinking about light and color than just “shading a drawing”.
Otherwise, I strongly suggest that you dig deep by yourself in the subject through books, classes or any opportunity you may find to learn about the effects of light and color.
// To illustrate this article I will use some of these drawings - please feel free to download the PNG image and follow the topics on your computer. The link will be at the bottom of the page.
My artistic background is from a 3D artist. So it seemed natural to me the idea that every object is constructed of basic shapes. Also, I was used to visualizing a polygonal mesh (those little squares) that forms the surface of an object.
If you don't have this “superpower” yet, I suggest you practice doing some drawing and trying to draw the wireframe over the object. The ability to visualize the three-dimensionality of 2D shapes will be crucial from this point forward.
Continuing with the abstraction that every object has an overlapped 3D mesh on it, also keep in mind that each square of the mesh (face of the polygon) has its direction (angle and orientation).
As in the image below, imagine that each of the polygons that make up the object, has little needles stuck into its surface.
Being able to imagine these needles (or the correct term in Computer Graphics: 'Face Normals') will make it easier to understand the 3D shape of the object. This visualization is very important to be able to paint light effects or reflected colors.
By understanding these two concepts, it is possible to render drawings (add colors and light effects) without necessarily thinking in the traditional idea of 'shading a drawing'.
Try the following:
(a) select 3 different shades of gray;
(b) choose a direction/angle on the object that will have the brightest tone. For these examples, I have decided that all upward-pointing planes of the object will get the lighter tone;
(c) apply the same idea to the angles. Match a tone with it’s normal direction.
Painting objects in this way does not result in realism cause we’re playing with a simpler model of rendering. But the result is a solid image with coherent “lighting”.
This type of rendering works great for presenting concept art designs.
Still thinking about this mode of rendering, remember that the three shades of gray you choose don't necessarily have to be something like option (A).
You can work with three shades of lighter grays (B) or maybe three shades of darker grays (C).
What matters is that their relationship (light, medium and dark) is kept.
Applying this concept by itself is a way to start understanding ways of working with different levels of exposure of the light in your illustrations.
Since we are talking about grayscale images, I will show you right away one of the ideas that, in my opinion, have the most impact on the success of an image. This is the idea of Value Composition (or Tonal Composition).
If we choose colors randomly, we may fall into the trap of creating a composition that doesn't favor the message we want to convey.
In the first example (A), I chose the common shades of gray that we usually think of when painting a treasure chest.
Knowing that the focal point of the image had to be the treasure inside the chest, this composition didn't help me much. In the thumbnail, notice how difficult it is to find a place to focus on the image.
In example (B), I thought on the arrangement of the tones and reserved the medium / dark tones for the chest and the light tones for the treasure. From the thumbnail, you can see how this was a better choice because the eye goes straight to the focus point of the drawing.
You can (and perhaps should) apply the idea of Value Composition to your character designs.
In the example below, drawing (A) has completely randomly placed tones. The design has become fragmented and it’s difficult to understand that it is a character.
In the composition of the drawing (B), the focal point was on the head and hands of the character. Those are good points to focus on a character design.
In (C) I even added a top-down gradient, further emphasizing the focus on the character's face.
With these important ideas behind us, let's move on to the rendering scheme that almost everyone learns when they start painting digitally: start the painting in grayscale first.
Starting the image with grays (or any combination of two colors) is a historically proven method for constructing the lights and shadows of an image.
With just two shades, it is possible to simulate a satisfactory lighting effect.
For now, ‘satisfactory’ means that the light accurately shows the 3D shape of the object rather than the mood of a scene.
In the example below, note how with only three shades (including the lines) it is possible to show the sensation of light reaching the object in different directions.
Keep this in mind when starting to render a design. Begin by illuminating the object in a binary mode (off/on, dark/light), then you introduce halftones, transitions and gradients.
In this binary illumination scheme, the third tone can be used to simulate the highlight of a light.
One thing I did wrong in the beginning was to overdo this lighter, third tone.
If the use of the lighter tone is in the same proportion as the light part of the object, the result is a burst light (B).
In image (C), note how restricting the lighter shade to a small part of the surface makes the effect look more like a highlight on a waxed surface.
For now, remember to put this extra tone very carefully.
Each object reflects light differently, and the proportion/intensity of the lighter tone will change. But remembering that the lighter gray is the reflection of light, and not the light itself, is a good start.
When we learn about light and shadow, the subject is presented to us through the classic method of “direct illumination” - note the following points in illustration (A):
(1) the specular point or reflection of the light on the surface of the object;
(2) the lit side on an object;
(3) the edge (core) of the shadow - the transition from halftone to dark;
(4) the dark side in an object;
(5) the reflected or bounced light;
(6) the cast shadow or absence of light;
The direct illumination method is used because it teaches us very clearly the “anatomy of the light”.
But when I started, I wish I had learned other lighting techniques like the “global illumination” model.
The effect of light and shadows in global illumination is much softer, as it indicates a very large and diffused light source. The gradient (transition between light and dark) is much softer than in direct illumination (B1) and the projected shadow is almost nonexistent - in fact, the only obvious shadow is the contact shadow or occlusion shadow (B2).
Global illumination or indirect illumination gives a clay-like effect to the objects. This type of render is now widely used in 3D because it is a lighting that emphasizes the 3D forms and also the local colors of the object.
In the example below, note how I was able to give a three-dimensional form to the helmet design without having to use lines or clear cut light and shadows shapes.
When doing this kind of rendering, you just need to think of the occlusion shadows - darken those areas on the surface of the object where the light would have trouble reaching.
The gradient used to paint these shadows must be smooth, with the darkest part briefly appearing near the line (or hidden part) of the object. Notice in the image the difference between the gradients - the one on the right is the best way to simulate occlusion.
Practice your techniques for painting occlusion shadows. Selection tools and the airbrush are the most suitable tools for the job.
Also, keep in mind that the darker areas must be reserved for the touching surfaces (contact points). In the example below, note how the proximity of the sphere to the plane creates different intensities and dispersions for the contact shadow. The further away, the softer and more scattered the shadow.
If properly used, indirect lighting and occlusion shadows are more than enough to show the 3D form of a drawing. Hence its usefulness and effectiveness in presenting production designs or concept art.
In the example I was able to get the 3D feel of the character's head just by placing some gradients in specific areas - a third tone was added at the end just to emphasize some planes.
Combining the Direct Illumination method with Global Illumination is one of the simplest ways to 'layer' the rendering process and achieve a 3D effect.
In the example below: (A) is the previous render made only with occlusion shadows; (B) is the combination with a direct light coming from the left; (C) is an example of how you can use just a shadow cutout to give a sensation of light hitting the object.
To combine those layered shadows I do like to use CLIPPING MASKS - this option uses the (non-clipped) layers below as a mask.
In the image below notice how AO and CAST SHADOW layers are clipped to my base, MASK layer.
Thinking of rendering 2D images like 3D software has practical benefits - one of them is to ensure your sanity! :)
Simulating nature by painting is extremely complex and requires combining / adjusting several variables. This is not an easy task.
In the past I have written an article where I show a very practical and efficient method for coloring in Clip Studio Paint. I suggest you read it before proceeding with this series.
In the next part, we're going to use some of those concepts and combine with Color. I hope I can provide you with some new ideas and insights about the subject.
Thanks for your reading.