Adobe illustrator cs4- P19

Adobe illustrator cs4- P19: Good designers have many tools at their disposal. Especially in an environmentwhere most designers have other powerful graphics applications, itcan be diffi cult to choose which one to use for a particular task. For example,a designer can apply soft drop shadows in Photoshop, Illustrator, andInDesign—is one application any better than the others for this?
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Adobe illustrator cs4- P19514 CHAPTER 15: PREPRESS AND PRINTING In truth, transparency has always been around—in raster form—in Adobe Photoshop. The only difference now is that you can apply these effects in vector form and still edit them late in your workflow. At the end of the day, these transparency effects will become rasterized, leaving you with the same result as if you had done everything in Photoshop. In any case, let’s take a closer look at what transparency is and how it works. Understanding Transparency Flattening Let’s start with a simple fact: PostScript doesn’t understand transparency. As you probably know, PostScript is the language that printers and RIPs speak. Native transparency is understood only by PDF language version 1.4 or newer (first present in Acrobat 5 and Illustrator 9). NOTE If you’ve used To print objects with transparency, Illustrator must “translate” any transpar- Photoshop before, ent artwork into a language that PostScript understands. This translationyou may be familiar with the process is called transparency flattening.term flattening, which com-bines all layers in a document. The process of flattening is simple, and Illustrator follows two cardinal rulesAlthough similar in concept, when performing flattening on a file:transparency flattening isdifferent. 1. All transparency in the file must be removed. 2. In the process of performing rule #1, the appearance of the file cannot change. Both of these rules are followed during the flattening process, with no exception. Obviously, all transparency has to be removed because PostScript doesn’t know what transparency is. Additionally, if removing the transpar- ency would result in your file changing in appearance, that would mean you could design something in Illustrator that couldn’t be printed, which doesn’t make sense either. If you think about it, if you’re removing transparency from the file and you’re also keeping the visual appearance of the object, something has to give, and that something is the editability of your file. Let’s take a look at an example of this. Flattening Artwork Let’s try an example of flattening: 1. Draw two different-colored circles, one overlapping the other. 2. Set the top circle to Multiply (Figure 15.10). LEARNING THE TRUTH ABOUT TRANSPARENCY 515 The nice feature of transparency is that you can move the top circle around or change its color, and any overlapping areas will simply mul- tiply. The problem is that PostScript doesn’t know what transparency is and doesn’t know how to print that overlapping area, so transparency flattening is required. Figure 15.10 By setting the top circle to the Multiply blending mode, you can see through it to the circle below, even with Opacity set to 100%.3. Select both circles, choose Object > Flatten Transparency, and click OK (don’t worry about the dialog box, which we’ll get to later). The file is now flattened. Does it look any different? It can’t, because of rule #2, but the file now no longer contains any transparency and can be printed on a PostScript device. The difference is that the file is no longer editable as it was before it was flattened. Upon selecting the cir- cles, you’ll find that the two transparent circles have now been broken up into three individual opaque shapes (Figure 15.11). Figure 15.11 Once the objects are flattened, the artwork is split up into individual opaque pieces, called atomic regions.This flattening process happens every time you print something with trans-parency. However, the flattening happens in the print stream, not to youractual Illustrator file. When you choose to print a file, Illustrator flattens acopy of your file and sends the flattened file to the printer, while leavingyour document intact. It wouldn’t be good if simply printing a file renderedit uneditable. In our example, we specifically flattened the file using the516 CHAPTER 15: PREPRESS AND PRINTING flatten transparency function to see the result ...