The Blend Tool has been part of Adobe Illustrator for a long time and it's very simple to work with. The tool creates objects that fill the space between two key objects. Let's say we have a square as object A and a circle as object B; the Blend Tool will create intermediate figure shapes between these two objects. You can add how many steps you want and it remains editable until you expand it. We can use this tool to create many effects. In this tutorial I'll show you how to use the Blend Tool to create semi-realistic halftones with lines.
1. Prepare Your Stock Image in Adobe Photoshop
To create a semi realistic illustration, a good stock is essential. Let's work with this image of this beautiful model. Another good point of this picture is the light source that creates dark shadows and visible halftones. This makes it easier to identity where our shading will be created.
Our work will be done in black and white, using black lines as halftones. Therefore a basic image treatment will help us to see the tonal values of the image and translate them into an illustration. We can discard the colors of the image now. Open the image in Adobe Photoshop and change the colors from RGB to Grayscale by going to Menu > Image > Mode > Grayscale.
Now, let's increase the contrast between the blacks and whites. This will reveal the tonal variations even more. Go to Menu > Image > Adjustments > Brightness/Contrast and then enter the values Brightness: 40%, Contrast: 40%.
To make the visualization of the halftones even easier, let's apply the Posterize filter on the image by going to Menu > Image > Adjustments > Posterize and set the Levels to 10.
Now we have our base image ready. Save this file (Menu > File > Save as… ) as "woman-grayscale.jpg" (Quality: 12). This way we keep the original picture and we have a copy to work from.
2. Place Your Saved Reference on Your Artboard in Adobe Illustrator
Open the "woman-grayscale.jpg" file in Adobe Illustrator. In the Layers panel, create two new layers ("Layer 2", "Layer 3"). Select the image in "Layer 1" and set the Opacity to 70%. You can see now the darkest shadows in the source image. Lock this layer.
3. Create Your Base Shapes with the Pen Tool
Select "Layer 2". With the Pen Tool (P) (or Pencil Tool (N) if you have a tablet), let's draw the shadows of face, hair and shoulders. Be sure to have the color black selected in the Color panel. Use the picture as a guide to draw the shadows.
4. Draw Your Lines Ready to Create a Blend
With the Pen Tool (P), let's draw some lines to define the face features and body shape. Use a Stroke Weight of 2 pt for the external contours and main facial features (nose, mouth, eyes). Use thinner Stroke Weight for the internal lines which are more delicate.
The interesting part of the drawing starts now! Let's do the halftones. Let's start in the girl's face. Draw a line (2pt Stroke Weight) close to the girl's shadow on the side of her face.
Select and duplicate this line and place it parallel to the original line.
Using the original picture as guide for the shading and then adjust the duplicated line to follow the shading. Use a Stroke Weight of 0.1pt.
5. Use the Blend Tool to Add Contouring
Now go to the Blend Tool (W) or double click on the Blend Tool symbol on the Tool panel. In the Blend Options window, select Specified Steps set the Spacing to 20, click OK.
With the Blend Tool (W) click on the thinner line (0.1pt) and then click in the second line (1pt). You will fill the space between these two lines with lines. See the thickness gradually changes, giving the halftone effect.
It's important to keep aligned the key points of the two lines, this way you can get a smoother shading transition. You can see a problem with the halftone in the region near the girl's mouth. To adjust these problems is just select some points and modify the curve. Automatically you'll be modifying the shading.
This is the basic way that the Blend Tool works, now we can do the other parts of the face: the nose, eyes etc... Always keep the thicker line near the shadows and use the picture as a guide to draw the shading.
Sometimes you need to change the steps of the Blend Tool to adjust the halftone to smaller areas. To do that, select the blend object (the pair of lines) and double click on the Blend Tool icon on the Tool panel. Just change the Specified Steps value.
Still adding the shading. The effect is like an old illustrated book.
6. Create Deeper Shadows with Cross Hatched Blends
I had to edit some points at the neck, to adjust the blending a bit more. Here, many points will create a texture that doesn't work when creating a soft skin effect.
You can use some crossed blended objects to create another halftone. At the neck and shoulders the crossed blend effect was useful to create deeper halftones.
7. Use Blends to Create Natural Movement in the Hair
The hair is a group of blended lines. You can play with these groups to create the hair texture and give it a natural movement. The Blend Tool is very efficient here.
8. Position Your Illustration
This is the illustration almost done. We can play with the negative spaces and add blended white lines in the dark shadows. It adds to the illustration some extra details that make it even more interesting. Some of these details are not, in fact, in the original picture, but, since we are "translating" the picture into the illustration, it's valid.
9. Add Further Blends to the Hair to Refine the Effect
You can get a nice flowing effect by crossing some the two lines of the blend.
This is the final look of the drawing, with all the shading done with blend, crossing lines and white lines (with blend) over black.
10. Add Blends to the Background to Finish off Your Composition
Now, with the same technique of blends, let's add some texture to the background. You can get some real nice effects by crossing the lines of the blending objects.
For the background, we can use this same object, duplicated and distorted, to create a texture of lines. This is the final look of the work. A bit messed up, but let's crop.
With the Rectangle Tool (M) draw a rectangle, over the picture. You can follow the same crop of the source image, if you want.
With the rectangle selected, go to Menu > Object > Crop Area > Make.
Well Done, You're Now Finished!
The Blend Tool is a simple but powerful tool in Illustrator. We saw that it's not so difficult to create complex shading and texture just using lines. With good references and creativity, it's possible to go further. Another good point of the Blend Tool is that you don't use much of computer memory; you get files with few megabytes even in highest resolutions.