Chapter 13: The Wonders of Blend Modes - Photoshop.CS.Bible [Electronic resources] نسخه متنی

Chapter 13: The Wonders of Blend Modes

It's High Time to Blend, Friend

When recording artist Paul Simon first asserted that there must be 50 ways to leave your lover, I couldn't help but think he was inflating the number a little. I mean, some of the methods he proposed were pretty flimsy. Does it really help Gus to get on a bus? Won't he just have to come back later for a clean shirt and a change of underwear? And when he cautions Roy not to be coy, Simon seems to be more interested in rhyming than providing concrete, helpful suggestions. In the end, the premise simply doesn't hold up. Between Jack, Stan, Roy, Gus, and Lee, Simon gets around to delivering a scant five ways to leave your lover, just 10 percent the number promised. What happened to just take a pill, Phil; don't be a slob, Bob; and show her the door, Thor? And how about the ladies? Might not Sue, Beth, and Anne benefit from some help in leaving their lovers as well?

Don't get me wrong, I love the song. But I think the songwriter might have had an easier time of it if he had decided to list the many ways you can combine and compare differently colored pixels in Photoshop. Forget 50, there must be 50 thousand! Just give it a nudge, Smudge; flutter and sway, Wave; give layers the purge, Merge — Clone Stamp yourself free. Granted, it would have failed commercially, but assuming Simon managed no more than his trademark 10 percent, the song could have filled seven albums.

Here we are, hundreds of pages into the book, and we've seen how you can smear and blur pixels, trace and sharpen pixels, distort and transform pixels, select pixels using other pixels, layer pixels in front of pixels, compare a pixel to its neighbors, copy pixels from one location to another, and much, much more. Any time that you edit, retouch, mask, composite, or filter an image, you're actually breeding the image with itself or with another image to create a new and unique offspring. Did I say 50 thousand? I meant 50 million!

And yet, despite all that we've seen so far, we're not even close to finished. Consider the subject of this chapter, blend modes, one of the most alluring experiments in Photoshop's great genetics laboratory. Alternatively known as transfer modes and calculations, blend modes permit you to mix the color of a pixel with that of every pixel in a straight line beneath it. A single blend mode can be as powerful as a mask, a filter, and a retouching tool combined. Best of all, it's temporary. As long as one image remains layered in front of another, you can replace one calculation with another as easily as you change a letter of text in a word processor.

To appreciate the most rudimentary power of blend modes, consider Figure 13-1. The first image shows me rendered in robot form on an independent layer with the New Yankee Photoshop set in the background. Aside from the text and accompanying color bars, these are the only layers in the image. For the most part, the robot is as opaque as if I had cut it out with scissors and glued it to the wood behind it. (Admittedly, I'd have to be very skilled with scissors and glue, but you get the idea.) The soft edges of the shadow to the right of the robot mix slightly with the pixels below them. But beyond that, every pixel is a digital hermit, steadfastly avoiding interaction.

Figure 13-1: One roboDeke means good training (top). But treat yourself to multiple roboDekes subject to all kinds of blend modes (bottom), and you get the kind of educational overload that leaves you begging for mercy.

The second image in Figure 13-1 paints a different picture. Here I've created several clones of the robot and mixed them with both the background and each other using Photoshop's wide array of calculation capabilities. The robot image itself never changes; each layer contains the same 400 or so thousand pixels that, when combined, scream out, "We are roboDeke!" In all, there are ten layers: three angled robots in the background, one apiece subject to the Hard Light and Linear Light modes on the left, followed by two overlapping layers, one the result of Linear Dodge and the other a function of Multiply and an Opacity value of 50 percent. I created the final photonegative robot using three layers, one subject to Difference, another inverted and subject to Screen, and then again inverted and again subjected to Difference.

Naturally, we'll get into the specifics of every one of these blend modes — including the ever-popular Difference sandwich — later in this chapter. But before we do, a few basics are in order. Photoshop gives you three fundamental ways to mix images:

The Layers palette: You can combine the active layer with underlying pixels using the Opacity and Fill values, along with the blend mode pop-up menu, all members of the Layers palette. next section. Blend modes are covered in the section after that.

Figure 13-2: The list of layers in the "Army of roboDekes" composition, with a few essential layer-blending functions labeled on right.

Blending options: Right-click a thumbnail in the Layers palette (Control-click on the Mac) and choose Blending Options to display the Blending Options panel of the extensive Layer Style dialog box. Along with the Blend Mode, Opacity, and Fill Opacity options, you get an assortment of advanced blending options, including the Knockout pop-up menu and Blend If sliders. The Knockout options let you use one layer to cut a floating hole into one or more layers below it. Using the Blend If sliders, you can drop colors out of the active layer and force colors to show through from layers below. For more information about these and other options, read "Advanced Blending Options" later in this chapter.

Channel operations: The so-called channel operations permit you to combine two open images of identical size, or one image with itself. Photoshop offers two commands for this purpose, Image Apply Image and Image Calculations. Largely archaic and completely lacking in sizing and placement functions, these commands are unique in that they provide access to two otherwise hidden blend modes, Add and Subtract. Simply put, unless a technique involves the Add or Subtract mode, or you want to clone two images into a third image window, you can mix images with greater ease, flexibility, and feedback using the Layers palette. For more on this lively topic, see "Whole Image Calculations" in the latter half of this chapter.

Blend modes are not Photoshop's most straightforward feature. There may even come a time when you utter the words, "Blend modes are stupid." They demand a generous supply of experimentation, and even then they'll try to fool you. I was a math major in college (with a double major in art, for what it's worth), so I well understand the elementary arithmetic behind many of Photoshop's calculations. And yet, despite roughly a decade of experience with blend modes in Photoshop and other programs, I am frequently surprised by their outcome.

The key, therefore, is to combine a basic understanding of how blend modes and other compositing features work with your natural willingness to experiment, grow, and bond with pixels. Sometime when you don't have a deadline looming, take a multilayered composition you have lying around and hit it with a few calculations. Even if the result is a disaster that you wouldn't share with your mother, let alone a client, you can consider it time well spent.