Interplay of blend modes and layers
Layers are a massively important part of digital painting, allowing you to organize and separate out different parts of your artwork. But there are many extra tricks that layers have to offer, one of which is to facilitate the use of blend modes. Blend modes can change the way a layer in your painting interacts with the layer underneath it to produce a range of visual variations.
There are a number of different blend modes to choose from, including Normal, Multiply, Screen, and Color, but understanding what each one does is not the easiest task. So to get started in figuring out how blend modes can heighten artistic expression, let's have a look at some of the most commonly used layer blend modes and examine when and how to use them in your iPad painting apps.
[ Kyle Lambert is a UK-based visual artist specializing in painting, illustration, and 3D animation.]
Normal is the easiest blend mode to understand because no actual blending takes place. Instead, anything painted on a normal layer will visually obscure what is beneath it.
As you can see in the example image, the red brush stroke is on a Normal layer which means the black and white background layer is now partially hidden beneath it. No blending has occurred.
When to use it: Normal is the default layer bend mode in most art apps and is often the most appropriate choice. It is best used when you are trying to achieve depth in a painting with solid objects. In this example image, the hand—which is on a Normal layer—obscures the background landscape as it would in reality. With any other blend mode, the hand would have mixed with the background, giving a less realistic effect.
The Multiply blend mode is often used to paint over and darken the layer below it. In this example, you can see how the red brush stroke—which is on a Multiply layer—appears as expected over the white, but gets darker as it blends with the darker background.
When to use it: Multiply is a great blend mode to use when adding shadows or tone to a painting, because the darker brush strokes blend into the color of the object. The Multiply blend mode is also a great method to use for coloring in a back and white sketch or photograph. The dark sketch outlines or shadow tones of the photograph will remain, allowing you to paint in color.
Screen is the complete opposite of Multiply in the blend mode universe. It is often used to lighten the layer below it. In this example, you can see how the red brush stroke this time appears as expected over the black, and gets lighter as it blends with the lighter background.
When to use it: In the same way Multiply can be used to paint in shadows, Screen can be used to paint subtle highlights onto an image. The Screen blend mode is also a useful way to change a black and white sketch into to a light color.
Overlay is a combination of both the Multiply and Screen blend modes. In this example, the red blends with both the light and the dark background and appears as expected over the middle gray background.
When to use it: If you are working with a black and white tonal sketch or photograph, multiply is a quick way to replace only the gray areas with color, leaving the light and dark areas unaffected.
The Color blend mode is one of the most useful for painters because it allows you to adjust only the color of the layer underneath it. This is great because typically, changing the color of something requires you to mix new shades.
When to use it: The image in this frame is a good example of how the Color blend mode can be used to change the color of the cartoon character's t-shirt. You can make changes to small areas like this, or even to the entire image—to achieve a sepia effect, for example.
More blend modes
There are many other blend modes available to experiment with, particularly in the ArtRage and ArtStudio applications. Many of these are similar in principle to the blend modes we've covered here.
Each mode is a different mathematical calculation of how the numeric value of each pixel in a layer will change when mixed with the pixel beneath it. Don't worry about learning the math behind each mode; instead, spend some time experimenting while you paint. You will soon discover which modes are most useful for your creative process and understand when best to use them.