In this two-part article, we’ll take a low-quality digital photo of my youngest son, Sammy, banging on a hopelessly busted piano:
And transform it into a work of otherworldly vector-based weirdness (below bottom). The primary instrument of this transformation will be Adobe Illustrator’s Transparency palette. But while Illustrator can belt out a medley, can it carry a tune? The answer is, yes, so long as Photoshop oversees the final production.
Here’s the idea: Illustrator allows you to assign varying levels of transparency to vector-based objects. That’s great because, as we’ll see, it makes for a remarkably versatile drawing environment. The problem is, Adobe’s original vector-based technology, PostScript, doesn’t accommodate transparency. And given that PostScript has long been and continues to be the professional-level commercial reproduction standard, this conflict seems to raise a red flag: How can Illustrator make art that PostScript can’t print?
There are a variety of answers to that question, but in truth, you don’t need to spend much time worrying about them. Granted, Illustrator has been known to offer up some tricky output instructions. And a dozen different PostScript RIPs might very well screw up those instructions in a dozen different ways. But there is always an arbitrator (not to mention, enabler) of an illustration’s printability, and that is Photoshop. All will be revealed in this two-part article: Part 1 coming out this week (June 30, 2008) and Part 2 three weeks hence (July 7).
Words of advice: While a fun project, these steps are not for the faint of heart. I’ve tried to make sure the information makes a modicum of sense to anyone, regardless of experience. And as a special bonus, you can click on any screen shot below to view a full-sized version of that same image in a separate window. But the steps will make the most sense to those with a working knowledge of Adobe Illustrator. To gain such knowledge, you are welcome to check out my commercial video series Illustrator One-on-One, available through lynda.com. Note: this article was written specifically for Illustrator CS3.
Step one: Changing the opacity of an attribute
Our job is to dress the photograph of Sammy in vectors so he looks like a combo Liberace/Elton John/Phantom of the Opera. We’ll start midway into the creation of the illustration, after I’ve already imported the photo of Sammy into Illustrator and established a few base objects.
I’ve given Sam a vector-based orange jacket. Let’s say I want the orange fill of the jacket to be translucent, so you can see through it to the stage elements behind young Sam. But if I reduce the Opacity value of the path to, say, 50%, I change fill and stroke alike, making the stroke look weak and just plain bad. The trick is to select the Fill attribute independently in the Appearance palette (which you get by choosing Window > Appearance). Target the orange Fill item in the Appearance palette and change the Opacity value in the control palette (at the top of the screen) to 50%, as demonstrated below.
Step two: Creating a knockout group
Problem is, you can see through the objects in the Suit group, which gives away the fact that the paths overlap each other. The conventional solution is to apply the Opacity value to the group as a whole instead of the individual paths. But if I did that, I couldn’t make the fill translucent while keeping the stroke opaque. So instead, I need to convert the group to a knockout group.
I first target the Suit group (which contains jacket and pants) by clicking on its circular “meatball” to the right of the word Suit in the Layers palette. Then I turn on the Knockout Group check box in the Transparency palette, highlighted with a tool tip below. If the check box fills with a box instead of a check mark, I click it again to select it for real. Now the various elements of the suit cancel each other out, forming one continuous, two-piece garment.
Step three: Applying an opacity mask
The tops of the orange jacket and white ascot overlap Sammy’s face, currently represented by a black silhouette. (Sammy’s face resides on a photographic layer below.) I could use the silhouette path to clip holes in each and every overlapping jacket path, but that would take more effort than it’s worth and potentially leave behind extra stroked edges. Better to cut one large hole in the Jacket sublayer using an opacity mask.
When making an opacity mask, white reveals and black conceals. This means that I want to make a black mask, one that conceals the overlapping edges of the jacket and cuts through to the underlying Sam. So I do like so:
- Select the silhouette head outline and move it in front of the Jacket sublayer.
- Shift-target the Jacket sublayer.
- Choose Make Opacity Mask from the Transparency palette menu.
- Turn off the Clip check box (also in the Transparency palette).
The silhouette disappears, clipping a hole in the Jacket and revealing Sammy’s head in the background, as below.
Tips and tricks: Ways to edit an opacity mask
Once you make an opacity mask, here are a few ways to manipulate it:
- Click on the opacity mask thumbnail in the Transparency palette to make the mask active.
- Shift-click the mask thumbnail to deactivate or active it.
- Alt-click (or Option-click) the mask thumbnail to view the thumbnail independently of the illustration (below).
- And finally, click the drawing thumbnail (in our case, the jacket) to return to the illustration.
Step four: Blending between groups
Now for a little meta-step0 that has nothing to do with transparency and everything to do with creative expression, flexibility, and all-around coolness. The keys on the Piano sublayer are actually a blend. But instead of blending between two paths—to create a custom gradient, for example—I made the keys by blending between two groups of paths. That’s right, Illustrator lets you blend between groups.
I’ll recreate things by releasing the Blend object. Each key group (called <Group> in the Layers palette) comprises three paths: a black key, a white highlight line, and a black line that represents the border between white keys. So here’s what I do:
- Select both groups and choose Object > Blend > Make to blend them together.
- Double-click the blend tool in the toolbox to bring up the Blend Options dialog box
- Specify 21 steps and click OK.
- Use the convert point tool to add control handles to the path-of-the-blend (shown selected below).
- Drag the control handles with the white arrow tool to change the speed of the blend and add some perspective.
Step five: Editing an existing opacity mask
The bottom edges of Sammy’s jacket and pants are visible through the piano and thus advertise to the world that I haven’t drawn everything. I need to use the piano to clip the leg stump away.
- Select the bottom blue path in the Piano sublayer and copy it.
- Then target the Jacket sublayer, click on its opacity mask thumbnail in the Transparency palette, and choose Edit > Paste in Front to paste the blue shape in place in the opacity mask.
- To make it a proper concealer, fill the shape with black and set its stroke to None (below).
Step six: Creating a gradient opacity mask
You can combine a gradient with an opacity mask to make a continuous fade. For example, let’s say I want to make the piano fade to transparency at the bottom of the illustration:
- Draw a big rectangle across the entire illustration and fill it with a black-to-white gradient with an angle of 90°, straight up. (Make sure the stroke is set to None.)
- Move this new path down the Layers palette so it sits directly in front of the Piano sublayer.
- Target both the gradient rectangle and the Piano sublayer and choose Make Opacity Mask from the Transparency palette menu, which converts the gradient to a new opacity mask.
The piano now fades from opaque at the top (where the mask is white) to transparent at the bottom (where the mask is black), as pictured below.
All right, gang, that ends Part 1 of your fast-and-furious introduction to the world of transparency in Adobe Illustrator. If you have any questions, don’t hesitate to throw up a comment and I’ll do my best to answer. In Part 2, we’ll experiment with blend modes, mask an entire layer, and render the entire illustration in Photoshop.