How to Shade Digital Art.

Grayscale Light and Shadow is a very basic and fundamental part of any artwork trying to reach any resemblance of realism; in the real world light and shadow is the only way humans can see the world around them – forming depth. 

If you want your digital artwork to be realistic or even represent your own twist of realism – mastering these fundamentals relating to how to shade digitally on a computer or device will catapult your work into a better place. 

This tutorial will help you to understand how light and shadow works and how to improve at shading your digital artwork!

For this tutorial we will touch on some Photoshop specific guides although almost any software can use these techniques including ProCreate, Clip Studio or any software that can be found on a Tablet, Mac or PC.

Light and shadow – how it works.

Let’s start by keeping it simple(ish) – a sphere. 

Core shadow, cast shadow and the terminator. 

Naturally, when a light source hits a sphere, only half of the sphere is hit by the light, leaving half of the sphere dark. The half of the sphere not lit up is called the core shadow. The line between the core shadow and the half of the sphere lit up by the light source is called the terminator.

This very simple concept defines the position of the light source in relation to the position of the object and the viewing angle. 

To demonstrate what this means I will start by stating: whatever side of the sphere faces the light source is shaded brighter while the other side, the core shadow, is shaded darker.  

Generally, the placement of the terminator comes with practise but to start you off, follow this simple rule.

If the light source is in front or behind the sphere, visualise the shape:

If the light source is above or below the sphere, imagine the shape:

Apply this shape to your sphere, choose which side you want to be the core shadow and there you have it.

Objects also cast shadows and these shadows are called cast shadows. Now cast shadows can get a bit more complicated – but don’t be alarmed. 

Light falloff.

If you point a light at a close surface, the edges of the light will be sharp. When it is pointed at a distant wall, the edge will be softer and lighter in color. This is called falloff. The closer an object is to the light source, the sharper the terminator (edge). The farther away it is, the softer and lighter in color.

Cast Shadow

We need to look at how objects interact with each other. For example, if there is a sphere between the light and another object, then the other object will not get as much light. This is called a cast shadow, because it means that there is an area where the light cannot reach that object.

A shadow’s shape is flat. But the area of blocked light is not always flat. It might have another object inside it, outside it, or even partially inside it. The border of the shadowed area will show a new terminator on that other object. You should think about a shadow as having 3D properties to better imagine its shape.

Occlusion Shadows

But there are some areas where even the reflected light can’t reach—for example, when two objects touch each other, creating a tiny area of shadow. This shadow is called a contact shadow or an occlusion shadow. Because it’s so hard to reach, it’s darker than any other shadow in the scene.

Step 1: Sketch and Load

Either bring your own sketch or any reference piece into your editing or drawing software. Lower the opacity of this layer so that you can draw over it and properly see what you are doing. I would suggest to about 30%. Next, create a new layer below the reference piece – this will be where you begin your drawing! (I suggest you lock the reference layer!)

Step 2: Outline and Base Layer

Now you can draw an outline around the object you want to shade whether this is done using a paint brush, a shape tool or a pen tool. Then fill in the shape as the base layer. This could be a 50% gray colour, acting as basic coloring.

Tip: To quickly fill in the area inside your shape use your magic wand tool (Shortcut W) to select either everything inside your shape or what often works better select everything outside the shape and Invert the selection. (Select -> Inverse). Then fill in the selection with the grey colour (Edit -> Fill).

Step 3: Core Shadow and Terminator

Duplicate the Layer and change its blend mode to Multiply. You should be able to see that the layer has become darker and will act as the core shadow. Next apply a Layer Mask to the top copy of the layer (The rectangular shaped donut if you are using photoshop).

To apply the initial illuminations to set out the terminator, paint the layer mask black. This will hide the areas you paint from the top layer leaving the lighter gray below it. Feel out where you want the illuminations to be or if you can use your refernece material to guide you.

Step 4: Natural Termination ( Blending the shadow ).

There are many ways of blending the terminator. Remember this isn’t a necessary step in all cases – it really depends on your reference and idea. Here are a few techniques:

1: Mixer Brush Tool. Use the mixer brush tool to carefully blend together the edges of the dark and light parts. To make the edges blend more use a larger brush.

2: If you want the blend to not be too intense and want less light falloff, you can use the blur tool to just make the edges less sharp.

3: Paint over the illuminated area with a a less hard brush. You can turn this down in the brush settings.

Step 5: Painting Cast Shadows

Everywhere in the image where there are overlapping objects you can paint a cast shadow. Make a new layer, set your brush to 50% grey and set the blending mode to Multiply again. Now paint on the new layer with your 50% grey brush over the areas that are covered by another object in the scene.

Step 6: Floor Cast Shadow

If you want a drawing to look realistic, it has to look real in context with the rest of the scene. Naturally an object creates a cast shadow across the surface its on. On a simple surface the cast shadow is of similar shape and of similar softness as the objects terminator. Therefore you can treat the cast shadow similarly to the core shadow. Create a new layer below and place it below the object you are shading. Like the rest, turn the layer into the Multiply blending mode and paint away. You should blend the cast shadow as you painted the core shadow in its level of softness. Drag this layer below the rest so the cast shadow is below the object.

Step 7: Contact Shadows

This step is where you will really see your drawing come to life as a 3D object. Many of us as we start off shading are hesistant when it comes to using super dark or super light colours. However, this is more often than not, exactly what is holding back your shading skills! Here is when we bring in some dark darks! Create a new layer above the rest with 50% grey, Multiply blending mode and a smaller brush at the ready. Keeping close to the object now, between where the core shadow meets a contact shadow. Paint the line inbetween; it is likely you will still benefit from some blending but this time not as much as before – (consider using the blur tool for this or just a softer brush). If needed you can adjust the opacity of this layer if it seems too dark.

Step 8: Highlights & Light reflections

This is the final step towards your shading masterpiece! Create a new layer of solid black. You could paint this in over a new layer or rasterise a solid color layer. Change the blending mode to screen, set your paint brush to a darker grey and paint over the parts of the object where you thing there would be a highlight or a bright reflection due to a light source. (Where the light source hits the object). Naturally these would be found in the lighter parts of your already existing work. Dont worry about going very bright!