Understanding transparency flattening
Video: Understanding transparency flatteningUp until this point we've explored some pretty cool features inside of Illustrator that allow us to take advantage of transparency. However, what happens when we try to print these documents? As we spoke about way back in Chapter 1 of this course, we know that PostScript, which is what drives most of the printers in our market, does not understand the concept of transparency, yet inside of Illustrator, because Illustrator's file format is based on PDF, we can create transparency as we've seen till this point.
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In this installment of Illustrator Insider Training, Mordy Golding shows experienced Illustrator users how to create transparency effects and ensure reliable printing results. This course reviews the history of vector transparency and covers features such as knockout groups, opacity masks, and transparency flattening. Mordy also shows how to establish a safe workflow when placing Illustrator graphics containing transparency in PostScript, PDF, and InDesign files. A free worksheet is included with the course.
- Understanding how transparency works across the Adobe applications
- Deconstructing the Transparency panel
- Adding transparency to gradients
- Understanding how overprints and knockouts work
- Using a gradient or complex appearance as an opacity mask
- The rules of transparency flattening
- Working with complex regions
- Understanding the relationship between flattening and stacking order
- Creating and sharing flattener presets
- Saving PDF files and using the PDF/X standards
Understanding transparency flattening
Up until this point we've explored some pretty cool features inside of Illustrator that allow us to take advantage of transparency. However, what happens when we try to print these documents? As we spoke about way back in Chapter 1 of this course, we know that PostScript, which is what drives most of the printers in our market, does not understand the concept of transparency, yet inside of Illustrator, because Illustrator's file format is based on PDF, we can create transparency as we've seen till this point.
So in order for us to make our documents compatible and be able to print on PostScript devices, they need to go through a process called transparency flattening. Now you may be familiar with the term flattening from Photoshop where maybe you have several layers and you flatten all those layers now into a single layer. Now in regards to transparency here inside of Illustrator, it's not exactly the same concept. Flattening transparency really has a different meaning and in this chapter we're going to completely understand this process of transparency flattening.
In fact, in this first movie here in the chapter let's understand exactly what transparency flattening actually is. I have this document open on my screen. It's called blueyellow.ai. It's actually based on a book that I grew up with that I really, really enjoyed. It was called Little Blue and Little Yellow. Now, in this document here, if I select this yellow shape right here, you can see that right now the Opacity of that shape is set to 100%, but it has the Multiply blend mode applied to it. That means any objects that appear beneath it will be multiplied with this object.
So if I simply take this shape right now and I kind of move it so that it overlaps this blue shape right here, where the two shapes overlap I'll actually see green. That's because this yellow object right now is set to the Multiply blend mode. But again, when I send this now to a PostScript device or to a printer, how is my printer going to know how to print this object, because PostScript does not know what the Multiply blend mode is or what it does? So the answer to that question is that this artwork gets flattened before it gets sent to the printer.
What I'll do now is I'll actually show you the results of flattening, I'll show you what happens, and then I'll explain to you at what part of the workflow this process happens. I'm going to start here by actually selecting both of these elements right now. I have two shapes inside of my document. If I go now to my Layers panel and I look at Layer 1, I have two shapes that I'm dealing with here. I'll go over here to the Object menu and I'm going to choose a command called Flatten Transparency. Now, before I do this, I'm just letting you know that the majority of the time that you're working inside of Illustrator, you'll never manually flatten a transparency on your own.
As we're going to see, Illustrator is just going to do this automatically for us. But because now I want to demonstrate to you the effects of flattening transparency, I'm going to invoke this command here. So I'm going to choose Flatten Transparency and this dialog box appears-- and don't worry about any of these settings. We'll actually go into detail about what each of these settings mean later on inside of this chapter. But for now, I'm going to use my default setting here and just click on the OK button. You can see right now that my file has been flattened. "Really?", you might ask. I mean after all, it looks exactly the same way now as it did just a moment ago.
That's the real nice thing about working with flattening transparency, as we'll see in the next movie. But for now, understand that if I take my Direct Selection tool, my white arrow, and I click on this shape right here and I move it away, you can see that Illustrator actually chopped it up into pieces. In fact, I can move this shape over here and then I have now a new shape in my document, which was not here before. So the process of flattening basically does this. It takes the transparency in my file and it breaks my file down into these pieces. These broken pieces that are the result of transparency flattening are refer to as atomic regions.
Each of these atomic regions do not have any transparency inside of them at all. In fact, if we take a look at my Appearance panel right now, as I select this yellow shape, it's no longer set to Multiply. It now has the default Opacity setting. These objects also all have default Opacity settings. Meaning that this artwork, if I just press Command+Z a few times to go back to where they were kind of sewn together right now, this artwork looks the same as it did before, yet it's completely compatible with PostScript, meaning that I can now print this. In other words, Illustrator sacrificed the editability of my artwork in order to ensure that it will print correctly on a PostScript device.
Now obviously, if every single time that I wanted a printed document, Illustrator would chop it apart into these atomic regions, that will be pretty bad because that would mean that I really would not be able to edit my artwork after I decided to print it. So it's important to understand that this flattening process does not actually happen to your document itself within your document. Every time that I press Command+P or Ctrl+P to print my document, Illustrator makes a copy of my document in the background. It flattens that copy of my document, then sends that flattened information onto the printer.
But my document itself never gets flattened because then again I would lose editability. All my artwork would get chopped up into pieces or these small atomic regions. So at this point you may be asking, "Hey Mordy, I understand now what this transparency flattening thing is. It takes my artwork, it basically reduces the transparency down into these atomic regions, which are completely opaque, and then the file prints just fine. So why do I need to know all this? Let Illustrator just handle everything in the background and I can rest without having to worry about all these technical details." Well, the answer is that unfortunately sometimes in this flattening process, some changes or differences may actually happen to your file itself.
These changes may degrade the actual appearance of your artwork when it finally gets printed. How may that happen? Well, that's something that we'll cover in the next movie.
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