Painting a portrait with the iPad

The first step toward producing a portrait is to find a model who is willing to let you paint them. You will need to figure out if the model is happy to sit and pose while you create the painting, or whether you are going to do a photo shoot and paint from photo references instead.

If you are new to drawing and painting—working with a live model can be a big challenge. Factors such as lighting and the sitter's pose will likely change over the course of the session, making it difficult to capture a good likeness. You may also find yourself limited to working around the model’s schedule, which can be frustrating and increase the pressure to achieve something in each sitting. I recommend taking photo references just in case you need to work from them afterwards.

With the canvas background set to 50 percent gray, you will begin the portrait by sketching in the basic facial proportions. This is essentially the process of outlining the shape of the sitter’s head and marking lines for where the mouth, nose, and eyes should be placed. If the sitter is looking straight at you as you work, it can be easier to pinpoint where the lines of the face should be located because of the overall symmetry. But if the sitter’s head is at an angle, it can take much longer to perfect.

This is the most important stage in producing your portrait because the rest of your painting will be created based on this framework.

For these initial sketching stages I recommend using a black paint brush set to 30 percent opacity, which will help reproduce a pencil-like line.

Once you are happy that the proportions of the portrait are accurate, you can then begin sketching the facial features based on these lines. The likeness of the person is what you are trying to achieve at this stage—the shape, size, and position of the eyes, nose, and mouth are all key areas to focus on here.

As the portrait progresses, you may choose to remove the initial sketch lines and use the eraser tool to clean areas of your sketch that become overly complicated.

When you complete this stage, it is important that you have achieved a good likeness of the sitter because the face will be difficult to fix going forward.

With the facial features captured, the next stage is to add tone to your sketch by gradually adding a three-dimensional quality to the portrait.

The key to shading is to use a black paintbrush with varying levels of opacity to build up the darker areas of the portrait. Start with the lightest shadows using 10 percent or lower opacity and gradually increase the opacity to paint in the darkest shadows.

After you add the dark shading, the next stage is to introduce highlights into the portrait by using a white brush. Here you are essentially painting with light onto the surfaces of the face that are most illuminated by light. In the same way that you did when painting the shadows, start painting with a low opacity value on the brush and increase for the brightest areas. These include the teeth, eyes, and other small highlights on the nose, lips, and jewelry etc.

At the completion of this stage, you should have a great finished black and white portrait. If you have no intention of adding color to your painting then you may decide to continue adding extra dark and light details. This will help increase the contrast and result in a more dramatic black and white painting.

To begin adding color, first create a new layer and then change that layer's blend mode to Color. This means that as you paint colors onto this layer, they will fuse with the black and white painting underneath, resulting in a colored portrait.

The quickest way to color the portrait is to identify two or three main colors—such as a skin color, a hair color, and a background color—and block in these key areas. Afterward, you can identify less prominent colors and paint these in where necessary.

To complete the portrait, I recommend creating a final layer on top of the other layers in order to paint in any missing details or colors that you were unable to add using the blend mode layer.

In this example, I added in a few extra light-blue highlights to the hair and eyes which I missed earlier in the highlight stage. When you are happy with the final portrait, you can then export it for printing or sharing with friends.

Here's a video of the steps used to create this portrait.