how to trace lines in illustrator

Ever wanted to turn your hand-drawn artwork into scalable vector graphics?

The Image Trace tool in Adobe Illustrator allows you to do just that! Whether you're working on a dubious doodle or a major masterpiece, just follow this 10-step guide to digitize it.

You'll need a copy of Illustrator for this tutorial. If you don't already have a subscription, you can get a free trial here.

1. First, make some line art with pen and paper.

We need a black and white drawing, but it can be as elaborate and complex as you like. You'll get the sharpest results using a pigment-based pen and clean, bright white paper. My personal favorites are Uni Pin technical pens.

You can use paper with dots or a grid, but try and get paper where the grid is printed in a light shade, because that will make it easier to exclude the grid when the image is digitized.

The Notebloc paper in the images below uses an inverted grid, which is easy to exclude.

Step 1

2. Scan or photograph your artwork

Use a flatbed scanner if you have access to one—they create the least distortion, because they keep the paper flat.

Alternatively, you can simply photograph the drawing using your phone. If you use your phone camera, try to get the page lined up with the four corners of the frame to minimise perspective distortion.

If your drawing is very small, like mine below, just photograph the part of the page you need, and try to line up the grid with the edges of the frame.

Step 2

3. Download the image to your computer and open Illustrator

If you're using your phone, the easiest way to transfer the image to your computer is probably to email it to yourself and download it.

Once you've got the photo saved to your computer, open up Adobe Illustrator and create a new document. It doesn't matter what size you choose for the initial artboard—I just went for A4 landscape.

Step 3

4. Place the image file into your Illustrator document

In your new Illustrator document, go to the File menu at the top of the screen, and select the Place command. Alternatively hit ⌘ Shift ⇧ P on Mac, or Ctrl Shift ⇧ P on PC.

Find your image file, select it, and then click and drag to insert the file into your document.

Step 4

5. Crop the image down

Right-click (PC/Mac) or ctrl+click (Mac) on the image, and select Crop Image.

Use the resizing handles to trim the image down to the area just around the art you want to convert to vectors. Hit Enter to finish croppiing.

Step 5

6. Turn on the Image Trace panel in Illustrator

Next, make sure that the Image Trace panel is turned on. Go to the Window menu, and select Image Trace to bring up the panel.

You might like to drag it over to your docked panels so that you can access it more easily next time.

Step 6

7. Set your image trace settings

With the image selected, click "Preview" in the Image Trace panel. This will show you what the conversion will look like with the selected settings.

Make sure that "Preset" is set to "Default", "View" is set to "Tracing Result", and "Mode" is set to "Black and White".

There are two other important settings to consider:

Threshold: This determines where Illustrator sets the white point when it analyses the images. If you reduce this setting to a smaller number, the white point is set lower, so more of the colors in the original photo become white. If you increase the setting, they become black. The Threshold setting is very useful if you're trying to exclude grey dots or gridlines in a scanned image.
Paths: This control is within the "Advanced" drill-down menu. Usually Adobe's default Paths calculation works well, but if you have very detailed artwork you might want to increase the number of paths that Illustrator creates. However, this creates a much more complex shape, and having too many complex shapes in a document can cause Illustrator to run slowly. It can also make it harder to edit shapes efficiently.

Step 8

8. Expand your paths

Once you're happy with how the preview is looking, it's time to "expand" the paths. This separates the shapes in the image, making it possible to manually edit them.

The Expand command can be found in the Options panel at the top of the Illustrator interface:

Step 9

9. Ungroup the shape

Initially, when the paths are expanded, they are all grouped together. If you want to edit the shapes or add color to them, the easiest way is to Ungroup the paths.

With the image selected, hit ⌘ Shift ⇧ G (Mac) or Ctrl Shift ⇧ G (PC), then click off of the image to deselect the group.

Step 9

10. Edit the shape

Using the Move tool V, have a go at selecting individual paths.

To add color, select the path you want to edit, then open up the Swatches panel (Window > Swatches, if you can't find it), and select a color.

I ended up doing something awful with gradients:

Step 10

Bonus tips

Creating enclosed space in your drawings will make editing easier. In the example above, there are two "enclosed" spaces in the original drawing—the circles for each of the lenses. This made it easier to apply colors to those shapes after the image was vectorized. To create enclosed spaces at the edges of your drawings, simply crop down your image so that the strokes run off the edge of the image.
Use Photoshop to tweak a drawing before vectorizing it. You might need to do this if you made a mistake in your drawing and want to scrub an area out. Just open up the original image in Photoshop, apply the threshold in Photoshop instead of Illustrator (Image > Adjustments > Threshold), and then use the Pencil tool to make your edits in black and white.

Thanks for reading!

Why not experiment with different drawing materials and the other settings available in the Image Trace panel? Feel free to share your creations with us on Twitter or Instagram :)