Introduction

Hi everyone! Mone here. My goal with this TIP is to make sure you have the right tools to understand how a back light works and how to paint it.

 

I’ll show you basic principles using a—oh so infamous—sphere and some stickmen-adjacent drawings, then I’ll apply those principles to an illustration, which I’ll explain the process of.

Tutorial

1. Where do I put the light(s)?

If your light is completely behind the character, we won't see it at all (this is not always true, and I’ll come back to it later): the character obstructs it.

(Ha! As you can see, even here, we see a bit of the light: when there’s dust or smoke or mist in the air, we can see a halo around the light source and around the surfaces it bounces off of.)

 

The trick, then, is to move the light source slightly to one side or another, thus creating a crisp rim light. This rim light helps us create a contrasting silhouette between the background and the main subject/character, which has two benefits:

 

1. It makes the silhouette more readable

2. It amplifies the value contrast, making us focus more on those areas

You can even add multiple light sources to help make the whole silhouette of the character stand out against the background!

2. Subsurface scattering

Big words, I know, but fret not: the principle is actually really simple. We call subsurface scattering (shortened as SSS) the thing that happens when a light hits a somewhat transluscent object, making it slightly glow under the surface.

 

Our first sphere wasn’t transluscent at all, making it impossible to see the light hitting it. But if it was, it would look something like this:

The more translucent an object is and the closer the light is to it, the brighter the SSS.

 

In this example, the only reason why the whole sphere isn’t glowing is because it’s not entirely translucent. The light has a longer distance to travel inside the sphere in the middle of it than on the side: little to no light reaches us in the middle, but a lot more on the side.

 

This can be a bit confusing, so let me show you a graph:

SSS is really interesting for us, because skin is a bit translucent (that’s the reddish line you sometimes see right next to a shadow in character illustrations), and hair is REALLY translucent: it can become almost white when light shines behind it!

3. Common value structures

Value structures are here to help you read a picture. You need a certain amount of brightness contrast between elements to be able to tell them apart, no matter their hue or saturation. The simpler your value structure, the easier it is to read your image.

 

You can mix and match value structures as much as you want, but here are some common ones I stumbled across while looking for references for this TIP:

The only thing you have to be careful about is to have your rim light always be the brightest thing on your illustration: if not, we won’t see it. That’s why we have no light background or light character in those examples.

 

Pro tip: if your character is very light, clip a multiply layer filled with a greyish color to it, then add your rim light on a new layer on top of everything.

 

Pro tip 2: try to give a wider value range to your focal point, like the face: that's achieved easily thanks to the brightness of the rim light, dark areas like eyes, mouth and nose and medium ones like the skin receiving ambiant/bouncing light.

Applying what we learned

I’m now going to paint an illustration based on what we learned.

 

The first thing I’m gonna do is paint a quick thumbnail to have an idea of my values and overall composition.

(A thumbnail should be very small to not get lost in details, hence the name!)

 

I want the main appeal of the piece to be the hair, glowing from the back light. I’m also adding some kind of secondary light to have a nice rim light from the right side, silhouetting the shoulders.

 

Notice how I’m using only a few values and making sure they contrast their neighbours?

 

I’m also intentionnally making the dress black so that it gets lost in the black background: it gives a mysterious feeling, as well as helps redirect the attention to the face and hair.

 

Now, let me show you the finished piece:

As you can see, I backtracked and decided to use only one light source, though I made it big enough to help silhouette the hips.

 

The hair was a mass of translucent strands: the more they stack on top of one another, the less light goes through them. The idea then was to paint the lighter strands first, then add darker ones gradually.

 

The hair on the right side of the character glows along its edges, where, just like our SSS sphere, the mass is thin enough for the light to go through it.

 

The big “trick” for this illustration is that you have to imagine a reflective surface behind the camera/us. The backlight reflecting on it is what enables us to see the skin. Without this out of frame surface, the character would be entirely dark except from the SSS and rim lights!

 

That’s it for this TIP. Hope it was useful. :)

Mone out!