How to mix colours
One of the most exciting things about painting is squeezing tubes and mixing vibrant and rich colours together on your palette. But when painting digitally, the techniques for mixing color can be totally different—even between apps. So to help simplify things, let's have a look at some of the differences between the various mixing techniques and break down some of the terminology you are likely to face when creating art on the iPad.
Hue is just a fancy word for colour, meaning pure values. Typically in an iPad painting app there are 360 possible colour hues to choose from across the rainbow—beginning and ending with red. When painting, think of the hue as the tube of paint that you choose to begin mixing with. In some applications, the hue appears as a vertical slider and in others it is represented in a ring or the outer edge of a wheel. Regardless of how the strip is presented, the hue range remains the same.
Once you have decided which hue you would like to paint with—in this case red—the next decision is how saturated that hue should be. Starting with white at zero percent—if you increase the saturation—the white gradually changes to red. In between you then get a range of lighter pink shades.
Last of all, the brightness slider allows you to adjust the brightness of the initial shade that you are mixing from. So instead of mixing from white—as in the previous example—you can begin from a darker shade of grey.
Combine Saturation and Brightness
If you then combine both the saturation and brightness sliders in different amounts, you can mix any colour that you would like to paint with. Understanding the relationship between brightness and saturation is a big part of learning how to mix colours digitally. Not only does it allow you to identify a colour and mix it correctly, but it also means that you can make subtle adjustments to the colour that you are already painting with.
An alternative method for mixing colours is to use RGB values. RGB refers to red, green and blue—with regard to light channels. In this example, having red and green equal with less blue mixes yellow. Most artists will prefer working with the HSB (Hue, Saturation, Brightness) method, as it closely relates to working with paint. RGB colour mixing makes more sense when relating to photography—where you are manipulating captured light.
One of the advantages of painting digitally is that you don't always have to re-mix the colours that you have already used in your painting. You can instead use the eye dropper tool to sample an existing colour from your canvas. In most of the painting apps, the Eyedropper icon is a pipette with a drop of paint coming from the end. Once you have chosen the Eyedropper tool, simply move your finger over the area of the painting containing the colour that you would like to sample and then release. This should then instantly capture the colour and allow you to being painting with it. In some of the iPad painting apps, you can activate the Eyedropper at any time by holding down your finger on the canvas for a few seconds.
Mixing colours on the canvas
In some situations, rather than use sliders, I have actually mixed the colour I needed to paint with on the canvas. This technique is similar to the way an artist would use a palette to mix paints together before painting with them. Generally, the way to do this is to find somewhere in the corner of your painting or on a blank layer and paint colours over the top of each other with varying levels of opacity. The lowering of opacity will lead to the colours blending together on the canvas—meaning that you can then use the Eyedropper to sample the colour that you need. Typically you then use the undo button to remove the mixing or delete the layer containing it. If you are using ArtRage, ProCreate, or ArtStudio, there are paint options for blending colours together that are already on the canvas. In ArtRage there is a palette knife tool, in ProCreate you have a smudge tool, and in ArtStudio a Wet Paint Brush. All these tools give you the opportunity to 'smudge' the colours on your canvas into each other.
Saving colours for later
When I am creating a painting I often find that I use the same colour more than once. Therefore it is useful that most painting apps provide the option to save your favorite or frequently used colours in a palette for later use. To do this, simply mix or sample the colour you would like to save and then drag the preview of the colour onto an empty space in the palette. Then, next time that you need to use that colour, all that you have to do is open the palette and tap on the saved colour block to carry on painting with it. The steps of this process may vary slightly from app to app.