Transparency for Print Output in Adobe Creative Suite 3

Designers Guide to Transparency

Saving and exporting files with transparency

Which file format to choose when saving or exporting files depends on how you plan to use the file. If you plan to place graphic files in documents created with other CS3 software, whenever possible, save in file formats that preserve live transparency—including native formats for Photoshop CS3, Illustrator CS3 and InDesign CS3 documents, or Adobe PDF 1.4 and especially the new PDF/X-4 standard. It’s important that you consider which file format your print service provider prefers delivered.

Adobe recommends that you use InDesign CS3 to create page layouts when placing transparency artwork created in Illustrator CS3 or Photoshop CS3. Using InDesign CS3 has the advantage of letting you save artwork in a format that supports live transparency.

Depending on how you plan to use a file, your save and export format options include:

If you’re creating a standalone Illustrator CS3 or InDesign CS3 layout with transparent objects that won’t be used in other layouts or applications, save the document in its native format using the Save command.
If you’re using InDesign CS3 to create page layouts, you can save files in any of these formats that support live transparency: native Illustrator (AI), native Photoshop (PSD), Adobe PDF 1.4, PDF 1.5, PDF 1.6, and PDF 1.7 files. InDesign CS3 supports transparency—importing, displaying, and printing—in these native and PDF files, and has built-in transparency features for use in laying out pages and building documents.
If you plan to use an Illustrator CS3 or InDesign CS3 layout in another layout or application, you must decide whether to save it in a different file format. For example, you should save a flattened version for placing in some applications, such as Microsoft® Word and QuarkXPress® 6.x and earlier, that do not support live transparency.
You can save or export an Illustrator CS3, Photoshop CS3, Illustrator CS3, or InDesign CS3 document in a non-native format, such as EPS. This flattens the artwork and renders it uneditable with the exception of Illustrator CS3 EPS files. You can reopen the latter, make the changes, export and flatten the file again, and then relink the placed graphic in InDesign CS3.

Note: You may be able to continue editing transparency in EPS or PDF files created in Illustrator 9 or later if they were saved with the Preserve Illustrator Editing Capabilities option (in the EPS or Adobe PDF Format Options dialog box). In the case of EPS and PDF 1.3, the file will contain flattened transparency; however, you can access the native Illustrator data by opening the file in an appropriate version of Illustrator. Then you can edit the live transparency and resave it with the appropriate flattener settings.

Advantages of saving native CS3 files

Saving files in native Photoshop CS3, Illustrator CS3, and InDesign CS3 formats has several advantages over using other file format options in the design process and prepress production:

File overhead is reduced. Saving a single, native version of a graphic instead of multiple, exported TIFF or EPS files, reduce the number of files to track, and the disk space required to store your graphics.
Editing is easier. InDesign CS3 allows direct linking to native Photoshop and Illustrator files, and Adobe PDF files, which lets you preserve live transparency throughout the page layout workflow.

In the production workflow, using native Photoshop CS3, Illustrator CS3, and InDesign CS3 files has these advantages:

There’s greater control at print time. Native file formats let you or the print service provider control the flattener and resolution settings up to the time you print, save, or export a job in a non-native file format (such as PostScript). Flattening at the latest possible stage produces the best results.
When it’s time to print the finished InDesign CS3 document, the printer can flatten all transparency at once directly from within InDesign using the flattener controls in InDesign CS3.
Your print service provider can change the output resolution and other print-related settings.
Preflighting can be done more effectively on live transparency than on flattened transparency.
Spot colors can be fixed—for example, if a document contains too many spot colors—if the transparency is live. Once flattened, spot colors involved in transparency cannot be altered.

Exporting EPS files

Saving or exporting a file as EPS always flattens transparency.

EPS file icon

Figure 19. EPS file icon

Illustrator CS3 can save files in its own EPS format and export files in EPS formats compatible with earlier versions of Illustrator. (Be sure to select the Preserve Illustrator Editing Capabilities option in the EPS Format Options dialog box to be able to continue editing Illustrator transparency.) Illustrator CS3 EPS files are well suited for a high-end print workflow because of the management of spot colors and transparency.

An Illustrator CS3 EPS file retains transparency information (unless resaved in another application), so live transparency is restored if the file is reopened in Illustrator CS3. Only Illustrator CS3 can read the transparent part of an Illustrator EPS file; Photoshop CS3, InDesign CS3, Distiller, and non-Adobe software use only the flattened part of the file.

You can export two kinds of EPS files using InDesign CS3:

By default, InDesign CS3 exports EPS files in which overprinting instructions are preserved wherever possible; these files are suitable for output on printing presses. In some limited cases, the flattening process preprocesses instructions for overprinting, and incorporates them with the transparency information.
InDesign CS3 can optionally export EPS files in which all overprinting instructions are preprocessed and the appearance of overprint is simulated for output on composite devices, suitable for desktop printing and proofing. This option is available when you select Simulate Overprint in the Export dialog box. As a rule, don’t use the Simulate Overprint option for high-end printing workflows.

Exporting Adobe PDF files

Adobe PDF 1.4 and later files can accurately display live transparency created by any Adobe transparency-savvy authoring and layout application.

PDF file icon

Figure 20. PDF file icon

Creating PDF documents using any CS3 component (except Acrobat Distiller) produces a PDF file with live transparency by default. Illustrator CS3, InDesign CS3, and Photoshop CS3 can import and export live transparency as Adobe PDF 1.4 and later files. Among other benefits, this format preserves spot colors and overprinting without flattening. The default Compatibility setting for exported PDF documents is Acrobat 5 (PDF 1.4).

(Adobe PDF 1.4 is also known as Acrobat 5 PDF; PDF 1.5 is Acrobat 6 PDF; PDF 1.6 is Acrobat 7 PDF; and PDF 1.7 is Acrobat 8 Professional.)

The Acrobat 5 (PDF 1.4) and later versions setting, produces PDF files with live transparency. PDF/X-4 files are based on PDF 1.4 or later and allow live transparency.

Acrobat 4 (PDF 1.3) and PDF/X-1a and PDF/X-3 options produce PDF files with flattened transparency. (You can continue to edit the native Illustrator data and transparency if you export the file with the Preserve Illustrator editing capabilities option in the Adobe PDF Format Options dialog box.)

It is often best to let your printer/prepress provider flatten transparency because final output is based on the provider’s settings. If you need to perform flattening, consider using PDF/X-1a.

(For more information, see Adobe PDF in a Print Production Workflow.)

Note: Adobe PDF 1.4 and later files created using Distiller do not contain live transparency because Distiller generates PostScript, which can only contain flattened transparency.

Exporting Illustrator CS3 files with transparency

If you intend to use an Illustrator CS3 graphic in another Illustrator CS3 document or Adobe graphics application, such as InDesign CS3 or Photoshop CS3, you have the option to save the Illustrator CS3 graphic as a native Illustrator (.AI), EPS, or Adobe PDF file, or you can export a native Photoshop (PSD) or TIFF file. Exporting Illustrator graphics in PSD format preserves live text, layers, masks, compound vector shapes, and more when you export Illustrator graphics in PSD format. For more information, see online Illustrator CS3 Help.

Native Illustrator file icon

Figure 21. Native Illustrator file icon

Table 2 shows Illustrator CS3 save/export file format options and how each format saves transparency. Choose File > Save or File > Save As to save an Illustrator CS3 document in a native Illustrator format or as a PDF or EPS file. Choose File > Export to save a native Photoshop (PSD) or TIFF file. If you use QuarkXPress for page layout, you must save Illustrator graphics as EPS or Adobe PDF 1.3 files. Native Illustrator files or graphics with live transparency cannot be placed into QuarkXPress 6.5 or earlier layouts. If you have been placing EPS files created with previous Illustrator versions into QuarkXPress documents solely to print the artwork, you should either directly print from Illustrator CS3 or place EPS files into InDesign CS3 for the most compatible printing experience.

Illustrator CS3 export file formats	Transparency embedded as
Native Illustrator CS3 (.AI)		Live or flattened
PostScript (for RIP or Distiller)		Flattened
Adobe PDF 1.3 (Acrobat 4), including PDF/X -1a and X-3 standards		Flattened
Adobe PDF 1.4 (Acrobat 5), PDF 1.5 (Acrobat 6), PDF 1.6 (Acrobat 7), PDF 1.7 (Acrobat 8), and PDF/X-4		Live; flattened if created using Distiller
EPS		Flattened*
Other formats (non-Illustrator EPS and TIFF)		Flattened**

Exporting Illustrator CS3 graphics to programs that can’t handle transparency

To use Illustrator CS3 transparent graphics in page layout programs that can’t handle transparency—especially if spot colors are involved and you intend to print separations—on exporting the Illustrator artwork, specify flattening settings and save in the Illustrator CS3 EPS format.

Currently, InDesign CS3 is the only page layout program that can interpret unflattened, live transparency in native Illustrator files and Adobe PDF 1.4 or later files. Illustrator EPS and Adobe PDF (1.3 and later) preserve spot colors.

Exporting InDesign CS3 files with transparency

To use an InDesign CS3 page containing transparency in another InDesign CS3 layout or another program, such as Illustrator CS3 or Photoshop CS3, export Adobe PDF or EPS files (choose File > Print). You can also use the Print dialog box to create PostScript files that can be converted to Adobe PDF with Acrobat (choose File > Print); because PostScript doesn’t support live transparency, transparency in these files will be flattened.

Table 3 shows InDesign CS3 save and export file format options, and how each format saves transparency.

Note: Choose File > Export to save Adobe PDF or EPS files. Choose File > Print to create a PostScript file.

Table 3. How InDesign CS3 exports transparency.

InDesign CS3 export file formats		Transparency embedded as
Native InDesign CS3 (INDD)		Live
PostScript (for RIP or Distiller)		Flattened
Adobe PDF 1.3 (Acrobat 4), including PDF/X-1a and X-3 standards		Flattened
Adobe PDF 1.4 (Acrobat 5), PDF 1.5 (Acrobat 6), PDF 1.6 (Acrobat 7), PDF 1.7 (Acrobat 8), and PDF/X-4		Live; flattened if created using Distiller
EPS		Flattened