The PDF format has been around for quite awhile, but its usage online and in print has exploded in recent years. As more companies expand their Web presence, they’ve found PDF to be an exemplary way to distribute information to their clients, as you can see from the examples in figure 1. Even Uncle Sam is in on the act. The IRS makes every tax form available as a PDF because they know PDFs are reliable and easy to use, which makes it all that much easier for them to collect your hard-earned money every year.
If you haven’t been using PDF, it’s probable that you may need to in the near future. Knowledge of using and exporting PDF files has become critical for many jobs. Since it’s one of the most diverse formats around, we’ll give you an overview of its uses and how it works with other Adobe products as well as a detailed review of how to save out PDF files from Illustrator.
Figure 1: PDF files can be used to distribute complex illustrations or simple forms.
PDF isn’t just for forms. It’s robust and can handle just about any design elements you want to throw at it. In this article, we’ll give you an in-depth look into Illustrator’s PDF export capabilities including options for Web and print, as well as different compression algorithms. We also give you a few tips on getting better results from Acrobat Reader and how to get the best image quality.
All of Adobe’s software supports some amount of PDF functionality, but Adobe’s main software for creating PDF files is Acrobat, currently at version 5. It’s a dedicated PDF application that’s vastly more robust than Illustrator’s handling of PDF. Many people prefer to use it, rather than Illustrator, to make PDF files.
Because Acrobat Reader — a separate utility for viewing and printing PDF files — is freely distributed, you never have to worry about people not being able to read your files. Acrobat Reader 5 supports transparency and other bitmap effects, which means all of Illustrator’s creative potential is at your disposal. Despite all this, there’s one thing about Acrobat Reader 5 that makes your illustrations look lousy, but it’s easy to remedy.
Acrobat Reader 5 doesn’t smooth line drawings by default. If you were sending an illustration to a client to view on her computer, it would be a good idea to tell her to change her Reader preferences. To change the smoothing preference in Reader, choose Edit > Preferences > General. In the resulting dialog box, select the Smooth Line Art check box. Smooth Type and Smooth Images are selected by default. It’s also really important to have the Smooth Line Art option selected if any of the text in your document contains an outline.
You can’t disable printing of a PDF when you’re exporting it from Illustrator, but you can do it from Adobe Photoshop. Photoshop saves out Photoshop PDF files, which unlike with Illustrator PDF files, you can disable for printing from Acrobat. The document can be printed from other applications but not from Acrobat. If you don’t want to give a client a printable version of a graphic or image, you can protect it somewhat by saving out a PDF from Photoshop rather than Illustrator. Or you can open your Illustrator PDF in Photoshop and just resave.
Illustrator and PDF
On the surface, working with Illustrator and PDF seems very clear-cut. Illustrator runs on a PDF core and it saves out PDF files as a native format.
Even though you can save PDF files out of Illustrator for both Web and print use, you can’t take full advantage of all of PDF’s possibilities with just Illustrator. This is mostly because Illustrator doesn’t support multi-page documents without the help of a plug-in and also because you can’t include hyperlinks or bookmarks from inside Illustrator.
However, if you’re designing a poster or other artwork for a client, it’s a great way to communicate and comment on proofs. You can email your clients a proof, which they can view on their computer and even print out if they want. We’ll take you through the options for Web and print preparation, so you can see the best options for each situation.
Saving a PDF
To save your document as a PDF, choose File > Save. In the resulting Save As dialog box, choose Adobe PDF (PDF) from the Format pop-up menu. Click Save and you’ll get the dialog box shown in figure 2. If you’ve never saved a PDF before, then the Default options are set, which are geared for print. The other choices under the Options Set pop-up menu are Screen Optimized for Web production and Custom, which is any variation from the two standards. The available options don’t change for either setting; some are simply enabled or disabled, but you can always change that.
Figure 2: This is control central for PDF export from Illustrator.
Illustrator breaks the PDF settings into two categories: General and Compression. We’ll step you through the General options you should use for preparing your files for the Web or print. The Default settings are geared toward PDF files for print. The options in the File Compatibility section are pretty much self-explanatory. Select the Acrobat setting you want, but keep in mind that Acrobat Reader 5 supports more options, such as transparency and spot colors. If you’re preparing a file for print, this is the best option to choose and it’s enabled for the Default settings. Some people planning PDFs for the Web select Acrobat 4 for online distribution because of higher compatibility, but for the most part 5 is the way to go.
The next option is Preserve Illustrator Editing Capabilities, which is enabled under the Default settings. By keeping it enabled, you give yourself and your print provider the ability to make any changes to the file that may become necessary during a RIP. However, there are also times when you don’t want it selected, such as when preparing files for Web use. This setting adds unnecessary bulk to the file, which is why it’s disabled under the Screen Optimized choice. And, more likely than not, you don’t want anyone editing your PDF files anyway.
The settings in the Options section require a little more thought, but only a little. The first setting is Embed All Fonts, which is enabled for both the Default and Screen Optimized settings. Even though this makes your file sizes larger, you want to leave this option enabled if the appearance of your document is critical. If you don’t choose to embed fonts, the PDF document will look just the same as it did in Illustrator because you have all the fonts on your computer. However, on other people’s computers, the text will reflow if they don’t have your fonts.
You can control how many fonts are embedded by setting the Subset Fonts When Less Than x Of The Characters Are Used option and specifying a percentage of a font set that must be used for the font to be worth embedding. For example, if you only use a few characters of a font to write a few headlines, it may not be worth embedding the entire font. Illustrator defaults to 100%, so you’ll need to choose a lower setting depending on the nature of your project.
If you’re working with documents for print, then you’re probably already working in a color-managed environment. If you’re sending your document to print on a press, then you’ll definitely want to select the Embed ICC Profile option. This tags your document with all of the Color Settings information that you were using in Illustrator, and it results in a print that more cl
osely matches your screen environment if you have a calibrated monitor. If you’re sending a proof, take care not to select Screen Optimized.
The Generate Thumbnails option just generates thumbnails for easy viewing when looking to place a PDF in Illustrator. It’s disabled for the Screen Optimized setting to conserve on file size.
Now, let’s look at the Compression settings. To do so, choose Compression from the General pop-up menu. The settings in the Color Bitmap Images and Grayscale Bitmap Images sections are the same, so we’ll cover them together. If you’re preparing files for dissemination online, you’ll want to select the Average Downsampling At option and specify a resolution. For Web display, these settings would default to 72 dpi. For print, you wouldn’t want to enable the Average Downsampling At option at all.
Also, when you’re saving for Web use, you don’t necessarily need to downsample. Images that you resize to 72 ppi and place in Illustrator will actually look a little better in the final PDF, though letting Illustrator do it results in a slightly smaller file.
Automatic, ZIP, and JPEG. You can choose whether to compress your images by enabling or disabling the Compression check box. For Web distribution, you’d definitely want to compress. Your options are Automatic, ZIP, and JPEG. The Automatic setting lets Illustrator pick what’s working best from the ZIP and JPEG choices. JPEG is lossy compression that does degrade image quality somewhat depending on your Quality settings. ZIP is lossless, like GIF, and you can specify a bit depth of 4-bit or 8-bit. Also, like GIF, is works better on images with a lot of solid color.
Image quality. There’s been more than a little confusion caused by the image Quality settings when compressing images. If you have Automatic or JPEG compression selected, then from the Quality pop-up menu, you can choose settings from Maximum to Minimum. You might think that the Maximum setting would give you maximum image quality, but it really gives you maximum compression and the lowest quality, while the Minimum setting gives you the least compression with the best image quality.
Monochrome compression. The Monochrome Bitmap Images section may be a little confusing to some people, because of the Grayscale setting above. In this case, Monochrome refers to bitmap images or images with only black and white and no gray tones at all. For these types of images, the compression options are also a little different. If you look at the Compression pop-up menu, you’ll see four choices: CCITT Group 3, CCITT Group 4, ZIP, and Run Length. Since we’ve already given you the ins and outs of ZIP compression above, we’ll look at the three new settings more closely:
- CCITT Group 3 compression is like the compression fax machines use to send transmissions.
- CCITT Group 4 is a superior version of the same type of algorithm. It basically compresses more efficiently than Group 3. Both are lossless compression formats, meaning they won’t affect the quality of your images.
- Run Length is a simple lossless form of compression. It can’t generate huge compression ratios. It can work on either 4-bit or 8-bit images like ZIP compression.
Wave of the Future
We’ve given you an overview of the PDF format and how things work with Acrobat. You also have a detailed knowledge of Illustrator’s specific export capabilities and should be ready for any situation that you might need to use it in the future.
This story is taken from “Inside Illustrator” (Element K Journals).
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