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Saving Files from Illustrator CS5 (part 3) - The Portable Document Format

10/21/2011 6:24:04 PM

The Portable Document Format (.pdf)

Walk up to just about anyone on the street these days and ask them about Adobe. Most will reply, “Oh, sure, I have Adobe on my computer.” What they are probably referring to is the free Adobe Reader file viewer, which enables just about anyone to view and print PDF files. Now that Reader has surpassed a billion downloads worldwide, PDF files are ubiquitous. PDF has become a standard format used not only by designers and printers but also by governments and enterprise corporations.

Over the past few years, PDF has become the format of choice for both printers and designers, replacing EPS and other formats. There are several reasons for this, including the following:

  • Smaller file sizes. PDF supports a variety of image compression techniques, resulting in smaller file sizes. In addition, users can easily create low-resolution files to send to clients for review and can create high-resolution files to send to printers for high-quality output.

    Tip

    You can instruct clients or users to download the free Reader at http://get.adobe.com/reader/. Reader is available for Mac, Windows, Unix, and a variety of mobile platforms.


  • A free universal viewer. Reader is free and available for nearly every computer platform, including handheld devices. This means a designer can deliver a PDF file and be assured that anyone can view the file correctly.

  • Ability to embed fonts. A PDF file is a single, self-contained file that includes all necessary images and fonts. This makes it easier to distribute and reduces the chance of error.

  • Easy to create. Designers can easily create PDF files from any Adobe application. Additionally, Adobe supplies a utility called PDFMaker, which comes with Acrobat, that enables users to instantly create PDF files from Microsoft Office documents or AutoCAD files. (Note that PDFMaker was dropped for the Mac in Acrobat 9.) A PDF virtual printer also enables a user to create a PDF file simply by printing a file from any application.

  • Security. PDF files can contain multiple levels of security that can restrict functionality such as printing or editing. This ensures the integrity of a file and gives designers the ability to protect their work.

By default, a PDF saved from Illustrator is also a dual-path file, containing both PDF data and native Illustrator data (Figure 7). In fact, if you think about it, saving a native Illustrator file and an Adobe PDF file is quite similar. When you save a PDF file from Illustrator, though, you can control a variety of settings in the resulting PDF data of the file.

Figure 7. If you’ve ever heard that Illustrator creates large PDF files, it’s probably because by default Illustrator embeds a native version of the file along with the PDF data, resulting in a PDF file that appears twice as large.


To save your file as a PDF file, choose File > Save, and select Adobe PDF from the pop-up menu. When you click Save, you are presented with the Save Adobe PDF dialog box where you can specify settings for how your file should be saved.

Different Uses of PDF Files

Before we discuss all the different options available when saving a PDF file, it’s important to realize that PDF files have many uses. For example, you might create a PDF file to send to a client so that they can approve a design, or you might create a PDF file to send to a printer for final output. Alternatively, you might even create a PDF file to upload to a website so that anyone can view the content. Each of these PDF files serves a different purpose, and therefore each can have very different settings. Just because you create a PDF file doesn’t mean you can use it for any and all purposes.

Note

PDF presets are similar to Distiller Job Options, which are simply a captured set of PDF settings.


Instead of having to manually specify PDF settings each time you want to create a file for a specific purpose, Illustrator offers to let you create Adobe PDF presets, which capture all the settings a PDF can have. At the top of the Save Adobe PDF dialog box, a pop-up menu lets you choose from some presets that ship with Illustrator (Figure 8), or you can define your own by clicking the Save Preset button at the bottom left of the dialog box.

Figure 8. Illustrator ships with several predefined PDF presets. If you’re using other Adobe Creative Suite components, any PDF preset you save in Illustrator also becomes available in all the other applications.

Acrobat Version Compatibility

When PDF was first introduced, it had limited support (spot colors weren’t supported until version 1.2), but as each new version of Acrobat has been introduced, Adobe has updated the PDF language specification (called PDFL for short) to include more advanced functions and to feature new capabilities.

Adobe released PDFL version 1.3 when it introduced Acrobat 4.0, which was the first mainstream version of Acrobat and the free Reader. With each new version of Acrobat, Adobe has also revised the PDFL version (Acrobat 5 = PDF 1.4, Acrobat 6 = PDF 1.5, and so on), although trying to remember all of these different numbers can prove quite confusing. An easy way to figure it out is to remember that if you add up the numbers in the PDFL version, it equals the corresponding version of Acrobat (1 + 4 = 5).

In any case, when you save a PDF file from Illustrator, you can specify which version of Acrobat you want your file to be compatible with in the Save Adobe PDF dialog box (Figure 9). Although saving a file using a newer version compatibility setting offers more options when saving, anyone who wants to view that PDF file needs to use a newer version of Acrobat or Reader to see and print the file correctly.

Figure 9. The Save Adobe PDF dialog box offers a plethora of settings for creating PDF files for a wide variety of purposes. The Compatibility setting determines the version of Acrobat that the resulting PDF file needs to display and print correctly.

The most important point to remember is that from a print perspective, there’s a line in the sand between PDF 1.3, which doesn’t support transparency, and all later PDF versions, which do support live transparency (Table 1).

Table 1. Acrobat Version Compatibility
Version of AcrobatPDFL VersionTransparency SupportMain Features Introduced
Acrobat 4PDF 1.3NoSmooth shading, digital signatures
Acrobat 5PDF 1.4YesTransparency, XML tagging, and metadata
Acrobat 6PDF 1.5YesLayers, JPEG2000 compression
Acrobat 7PDF 1.6YesObject-level metadata, AES encryption
Acrobat 8PDF 1.7YesEnhanced 3D support, PDF packages

The PDF/X Standard

Imagine the following scenario: A designer submits a PDF file to a printer for final printing. When the job is complete, the designer is horrified to find that the wrong fonts printed and that the colors weren’t anywhere near close to those that appeared on the screen when the designer designed the job. How did this happen? After all, didn’t the printer say they accept PDF files? For designers, and especially for printers, this is a scenario that unfortunately happens too often.

This happens because PDF is a “garbage in, garbage out” file format. Whatever you put into it, that’s what you can expect to get out of it. If you don’t embed your fonts when you create a PDF file, a printer can’t print your file unless they also have your fonts. If you embed RGB images when a printer needs CMYK, you will see color shifts in your output (some devices may not print RGB images at all).

With so many other possible things that could go wrong with a PDF file, printers and publishers realized that they needed a way to ensure that a PDF file meets certain requirements before it is submitted for final printing or publication.

One way to do that was by providing designers with a detailed list of the settings they needed to use whenever they created a PDF file. Although this was a nice idea in concept, printers and publishers soon realized that designers use a variety of different programs, and each has different ways of creating PDF files. They also realized this meant that each time a new version of software was introduced, a designer would need to learn new settings.

Instead, an International Organization for Standardization (ISO) standard was created, called PDF/X. A PDF/X file is not a new kind of file format but rather a regular PDF file that simply meets a list of predefined criteria. Now, when a designer submits a PDF/X file for final printing, a printer can assume that the file meets the minimum requirements to reproduce it correctly.

By choosing a standard from the Standard pop-up menu in the Save Adobe PDF dialog box, you are embedding an identifier in the PDF file that says, “I am a PDF/X-compliant file.” Certain scripts and preflight utilities can read these identifiers and validate PDF/X-compliant files in a prepress or publishing workflow. See the sidebar “Understanding Supported PDF Standards in Illustrator” for an explanation of the different kinds of PDF/X versions.

General PDF Settings

The General panel of the Save Adobe PDF dialog box contains several important settings that determine how your PDF file is saved:

  • Preserve Illustrator Editing Capabilities. The Preserve Illustrator Editing Capabilities option embeds a full native Illustrator file in your PDF file. This allows Illustrator to reopen and edit the file with no loss in editability. This option is turned on in the default preset, but turning this option off effectively cuts your file size in half and also reduces how long it takes to save a PDF file (Figure 10). If you want to send a file to a client for approval, for example, you can take this approach to create a smaller PDF file (which is also not as editable should they try to open it in Illustrator). If you do deselect this option, make sure to always save a copy of your file, because you won’t be able to reopen the smaller PDF and edit it as a fully editable file.

    Figure 10. By turning off the Preserve Illustrator Editing Capabilities option, you can create a PDF file that is smaller and suitable for posting to the web or sending via email.

  • Embed Page Thumbnails. With the Embed Page Thumbnails option selected, Illustrator creates thumbnails for each page. You can display these in Acrobat by choosing to view the Pages tab. Be aware that the thumbnails increase the file size somewhat, however.

  • Optimize for Fast Web View. Selecting the Optimize for Fast Web View option enables streaming, allowing those who view the file online to view parts of the document while other parts are still loading.

  • View PDF after Saving. It’s always a good idea to take a look at a PDF on your screen to make sure it’s okay before you release it to a printer or to a client. Selecting the View PDF after Saving option launches Acrobat and opens the file after the PDF file is created.

  • Create Acrobat Layers from Top-Level Layers. If you choose to save your file with Acrobat 6 (PDF 1.5), Acrobat 7 (PDF 1.6), or Acrobat 8 (PDF 1.7) compatibility, you can have Illustrator convert all top-level layers to PDF layers. You can view a document with PDF layers in either Acrobat or the free Reader, versions 6.0 and newer (Figure 11). In addition, Acrobat layers can be turned on and off when the PDF is placed in an InDesign document.

    Figure 11. When a file is opened in Acrobat or Reader, the viewing of layers can be toggled on and off.
PDF Compression Settings

The Compression panel of the Save Adobe PDF dialog box offers a variety of settings for compressing the images and art that appear in your file (Figure 12). One of the benefits of using PDF is that you can specify a variety of image settings for each need. For example, when you send a file to a client for review, you want to create a small file that transmits quickly via email and you might set all images to resample at 72 ppi. However, that same file, when transmitted to the printer for final output, needs to contain high-resolution images, which you might set to at least 300 ppi.

Figure 12. The Compression panel of the Save Adobe PDF dialog box lets you determine which image types will be resampled, as well as choose the compression method in which to do so.

When you create a PDF, Illustrator has the ability to resample an image. Resampling is a method used to change the resolution of a raster image. Although upsamplingdownsampling removes pixels from a file, resulting in a lower resolution and a smaller file size. Obviously, downsampling an image results in loss of image detail and is therefore inappropriate for final output to a printer. adds new pixels to a file,

  • Resampling settings. Illustrator can apply different settings to raster images that appear in your file, according to image type and resolution. You can specify these settings for color, grayscale, and monochrome bitmap images. More importantly, you can define a threshold for when images will be resampled. The Do Not Downsample option leaves images at their native resolutions. Alternatively, you can choose from three different types of downsampling (Average, Bicubic, and Subsampling), which reduce the resolution of any raster images in your file according to the threshold settings. The first value is for the resolution to which you want images to be downsampled. The second value determines which images in your file get downsampled. For example, if you set the first value to 72 ppi and the second value to 150 ppi, then any image in your file that exceeds 150 ppi is downsampled to 72 ppi. However, if your file contains an image that’s set to 100 ppi, that image is not downsampled and remains at 100 ppi because it falls below the threshold.

  • Compression and Image Quality. In addition to resampling raster images, PDF also uses compression techniques to further reduce the size of a file. Different methods are used for compression, or you can choose None to disable compression completely (see the sidebar below).

  • Compress Text and Line Art. To achieve smaller file sizes, select the option to compress text and line art. This uses a lossless method of compression and doesn’t sacrifice quality in your file.

PDF Marks and Bleeds Settings

Note

The Bleed settings you specify in the Marks and Bleeds panel define the bleed box values in the resulting PDF.


The Marks and Bleeds panel of the Save Adobe PDF dialog box (Figure 13) is strikingly similar to the Marks and Bleeds panel you’ll find in the Print dialog box. Here you can specify whether your PDF should have printer’s marks and whether the document will have bleed space added. If you already set a bleed setting when you created your document or in the Document Setup dialog box, you can set Use Document Bleed Settings to use those values.

Figure 13. The Marks and Bleeds panel of the Save Adobe PDF dialog box lets you create PDF files with crop marks automatically. Additionally, the Bleeds settings make it easy to turn bleed on or off depending on to whom you are sending the PDF file.

PDF Output Settings

The Output panel of the Save Adobe PDF dialog box (Figure 14, on the next page) gives you control over what color space your PDF is saved in and whether you want to include image color management profiles in your PDF. Additionally, you can specify color management settings for files that will be saved using one of the PDF/X standards.

  • Color. When you create a PDF file, you can specify a color conversion for the file. In the Color Conversion pop-up, you can choose No Conversion, in which case the color values and color space will remain untouched, or you can choose Convert to Destination and choose from the Destination pop-up options to convert the color values or color space using a color profile of your choice. You can also specify when Illustrator will include color profiles in the PDF file.

  • PDF/X. When you create a PDF/X file, you must specify a color profile intent; with PDF/X-1a, this is usually set to SWOP. You can also choose to mark the file as being already trapped, which is useful in workflows where trapping may occur in the RIP. If you trapped a file in Illustrator (either manually or via a plug-in such as Esko-Graphics’ DeskPack), identifying the file as already trapped prevents the file from being trapped again in the RIP.

Figure 14. The Output panel of the Save Adobe PDF dialog box gives you the ability to convert all objects to a specific color space. For example, when saving a PDF/X-1a file, any linked RGB images are converted to CMYK automatically.

PDF Advanced Settings

The Advanced panel of the Save Adobe PDF dialog box (Figure 15) allows you to specify how fonts are embedded in your PDF file and how transparency is flattened, if necessary.

  • Fonts. By default, Illustrator embeds subsets of fonts when saving a PDF file. A subset simply means that Illustrator includes only the parts of a font that are required to view and print the text you have in your document. If a font is protected, however, Illustrator does not embed the font. See the sidebar “Font Embedding and Permissions” for more information.

  • Overprint and Transparency Flattener Options. If your document contains overprint settings, you can choose to preserve or discard them. Additionally, if your file contains transparency, you can choose a transparency flattener preset to control how the transparency is flattened. For more information on both overprinting and transparency. It’s important to note that these two settings are applicable only when you’re saving a PDF file with Acrobat 4 (PDF 1.3) compatibility because all other versions support transparency and don’t require flattening.

    Figure 15. The Advanced panel of the Save Adobe PDF dialog box allows you to specify a transparency flattener preset when saving to PDF 1.3 (all other versions support live transparency).

PDF Security Settings

In today’s world, security has become a priority—not only in airports but with regard to electronic communications and documentation as well. One of the benefits of using PDF files is the ability to password-protect them so that you can control who can view or edit your file.

The Security panel of the Save Adobe PDF dialog box (Figure 16) allows you to specify two kinds of passwords to protect the content of your PDF file:

  • Document Open Password. A document open password, also referred to as a master password, controls who can open your PDF file. If a user attempts to view the PDF, they are prompted for a password. Upon entering the password, the user is able to view the file. The file will not open if the password is incorrect.

  • Permissions Password. A permissions password controls what a user can do with a PDF file once it is open on their screen. For example, a user who has the Professional version of Acrobat or a variety of Acrobat plug-ins, such as Enfocus PitStop, has the ability to edit a PDF file. Even if a file has a master password, once a user opens the file, they are free to do with the file as they please. By specifying a permissions password, you can restrict what a user can do with a file, even once they’ve opened the file in Acrobat Professional. For a detailed explanation of the different permissions settings, see the sidebar “Did You Ask for Permission?

Figure 16. The Security panel of the Save Adobe PDF dialog box allows you to choose a password that will restrict how your PDF file can be edited.

Did You Ask for Permission?

The permissions settings in Illustrator give you control over the actions a user can take with your PDF file once they’ve opened it. You can find these options in the lower portion of the Security panel in the Save Adobe PDF dialog box:

  • Printing. Choosing None disallows the printing of your file. Users are able to view the file in its entirety on their computer screens, but their Print command is dimmed (Figure 17). Choosing High Resolution enables full printing of the file. When using a compatibility setting of Acrobat 6 or newer, you can also choose the Low Resolution setting, which forces all pages to print only as raster images at 150 dpi.

    Figure 17. If you use a permissions password to restrict printing, a user without the password is able to view the document but is not able to print the PDF file.

  • Changing/editing. Choosing None disallows all editing of your file. Users are able to view the file in its entirety on their computer screens, but all of Acrobat’s editing tools are disabled. Four additional settings restrict specific types of edits. For example, by choosing the Filling in Form Fields and Signing setting, you allow users to fill out PDF form fields and to digitally sign the file, but this setting disables all other editing features.

  • Copying. If you want to prevent users from copying content from your PDF file and pasting that data into other applications, deselect the “Enable copying of text, images, and other content” option. However, by doing so, you may affect the accessibility of your document, especially for users who rely on screen readers to speak the content of files. These screen readers copy the text and paste the data into an application that reads the words to the user. When you select the option to enable text access to screen readers, Acrobat allows the copying of text if it senses that the application that’s copying the data is a screen reader. You can also enable a user to copy the metadata from a file.

 
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