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Learn to combine Brushes, vector tools, and Pathfinder to create crisp and clean line-art from a sketch. The finished product can be exported into Photoshop or a similar program for digital painting, or used as black and white line art on its own. This tutorial assumes basic knowledge of the Pen Tool (P). This tutorial uses techniques for pressure sensitivity tablets, but it can be completed with a mouse.
Choose a sketch you'd like to ink in a standard image file format (like .jpg, .png, .gif, etc). You don't need a high quality scan or high resolution image because we'll be inking over it vector elements. I'll be working with this sketch I drew of a warrior.
Create a new Illustrator file. (mine is 10 inches x 10 inches) Go to File > Place, and find your sketch. The sketch will appear on the artboard in its own layer as a linked file. Name that layer "Sketch."
Lock the "Sketch" layer and create a new layer above it. Name this layer Line Art. We will be inking in this new layer.
Now we will prepare the Brush. Open the Brushes window (Window > Brushes) and Double-click the 3 pt. Round brush to open Brush Options. I want the brush to be a little bigger, and for the width to respond to Pressure. I have set the Variation to the maximum. (If you are using a mouse, select Fixed.)
Select the Painbrusth Tool (B). Begin tracing over your sketch, one line at a time. Each brush stroke will become its own path in the Line Art layer. Each line doesn't have to be perfect - we will fix them later.
You may wish to change the size of the brush as you go. A smaller brush will work better for finer details, for example. To change the brush, double-click on the brush in the Brushes Window and adjust the settings. A dialog may appear - select "Leave Strokes" so that brush strokes you've already made won't be changed.
Continue to trace over your sketch, line by line. If you want to check your progress, turn off the Visibility for the "Sketch" layer.
This sketch has both flowing, organic lines (clothing) as well as hard-straight lines (armor, sword). I'll use the Paintbrush tool for the flowing lines, and use another technique for the hard lines later. (Step 9) As you can see, it's not perfect; some lines are wobbly, others end too early or too late. That's okay.
Create a new layer called "Armor." Select the Pen Tool (P). Adjust the weight by opening the Stroke Window. Draw small sections of the armor at a time, clicking to create anchor points at the corners. To make a curved line click, hold and drag. Adjust an anchor point by using the Direct Selection Tool (A). (This tutorial assumes basic knowledge of the Pen tool. If you need to review how to use the Pen tool, see this tutorial.)
By now you should have all the lines created, either with the Paintbrush Tool, or the Pen Tool. Now it's time to begin cleaning everything up.
We'll work with the Line Art layer first. Turn the Visibility off on the "Sketch" layer, and lock the "Armor" layer. Select the "Line Art" layer so that all paths in that layer are selected.
Go to Object > Expand Appearance. This will turn each path into a shape.
Using the Direct Selection Tool (A), we can adjust each line to be exactly what we want. Move the anchor points, and use the handles to adjust the shapes of the lines.
- Find places where a line overlaps into another area.
- Sometimes it will look better if a line ends in a sharp point, not a rounded point. (See the picture for this step - the wrinkle between her nose and cheek looks better tapered to a point.)
- Sometimes the thickness, position, or length of a line isn't right. Adjust them to be just right.
Use the Pathfinder to combine parts of the line art to make further edits. Use the Selection Tool (V) and hold shift to select multiple shapes. Open the Pathfinder Window and select Unite. Now you can more easily fix the imperfections in more complicated intersections.
In some places, a line overlaps an entirely different part of the drawing. Here, a line in the hair overlaps the fingers. I need to remove a whole section of that line. Using the Selection Tool (V), double click inside the shape that you will modify, putting the shape in Isolation Mode. This way we will not disturb the other parts of the sketch while we work.
Select the Eraser Tool (Shift + E). (Double-click to open Eraser Tool Options to change its diameter.) Erase the part of the line you don't want anymore. Double click (with the Selection Tool (V) anywhere off your current shape to leave Isolation Mode.
Repeat Steps 13, 14 and 15 until your organic lines in the "Line Art" layer are clean and all the lines look the way you want them to. Then repeat Steps 12, 13, 14 and 15 to the "Armor" layer, until all the lines are clean and where you want them.
Unlock both the "Armor" and "Line Art" layers, select all objects in both groups. Change their fill color to black.
Before we merge all the line art together, I want to save a back-up in case I want to go back and edit it later. Create a new layer and name it "Final Line Art." Copy all objects from "Armor" and "Line Art" and paste them into "Final Line Art." Turn off the Visibility for the "Armor" layer and "Line Art" layer.
With all objects in "Final Line Art" selected use the Unite option in the Pathfinder to combine all the lines into one combined object. You now have clean line art of your sketch with a transparent background! It is 100% scalable and 100% editable.
To use the line art in Photoshop for digital painting, create a new Photoshop file. In Illustrator, copy and paste the combined line art object we just made in the "Final Line Art" layer. In Photoshop, paste it. A dialog will appear.
- Smart Object will maintain a relationship with Illustrator. You'll be able to double-click the object in the Layers Panel and make edits to the object on the fly in Illustrator.
- Pixels will convert the vector format into a raster format. It will no longer be scalable or editable with paths and anchor points. But you'll be able to merge the line art in with your painting.
- Path creates a path but will not be useful as line art. I do not recommend this option.
- Shape Layer creates a layer in Photoshop's vector format. You'll be able to use Photoshop's light vector tools to manipulate the anchor points in this object. I most frequently use this option because it's simple.
You're done! It's time to start adding the colors in. You can keep working using Adobe Illustrator or Photoshop, it's your choice. if you would like to learn more about Photoshop, be sure to check out Psdtuts+