Preparing Graphics Files | Adobe InDesign CS3 Bible

InDesign offers support for many major formats of graphics files. Some formats are more appropriate than others for certain kinds of tasks . The basic rules for creating your graphics files are as follows :

Save line art in a format such as EPS, PDF, Adobe Illustrator, Windows Metafile (WMF), Enhanced Metafile (EMF), or PICT. (These object-oriented formats are called vector formats. Vector files are composed of instructions on how to draw various shapes .) InDesign works best with EPS, PDF, and Illustrator files.

Save bitmaps (photos and scans ) in a format such as TIFF, Adobe Photoshop, PNG, JPEG, PCX, Windows Bitmap (BMP), GIF, Scitex Continuous Tone (SCT), or PICT. (These pixel-oriented formats are called raster formats. Raster files are composed of a series of dots, or pixels, that make up the image.) InDesign works best with TIFF and Photoshop files.

Note ‚

PICT files can be in vector or bitmap format depending on the original image and the program in which it was created or exported from. If you enlarge a PICT image and it begins to look blocky, it's a bitmap. Similarly, EPS and PDF files can contain bitmap images as well as vector ones.

Tip ‚

If you output to high-end PostScript systems, make EPS and TIFF formats your standards, since these have become the standard graphics formats in publishing. If you're working almost exclusively with Adobe software, you can add the PDF, Illustrator, and Photoshop formats to this mix. (The Illustrator and PDF formats are variants of EPS.)

Graphics embedded in text files

Modern word processors typically support in-line graphics, letting you import a picture into your word-processor document and embed it in text. Word, for example, lets you import graphics, and InDesign, in turn , can import the graphics with your text. But graphics embedded in your word-processor document via Mac OS 8 and 9's Publish and Subscribe or via Windows's OLE will not import into InDesign.

In-line graphics will import as their preview images, not as the original formats. This means that in most cases, you'll get a much lower resolution version in your InDesign layout.

Tip ‚

Despite their limitations, the use of in-line graphics in your word processor can be helpful when putting together an InDesign document: Use the in-line graphics whose previews are imported into InDesign as placeholders so that the layout artist knows you have embedded graphics. The artist can then replace the previews with the better-quality originals . If you find yourself using several graphics as characters (such as a company icon used as a bullet), use a font-creation program like Pyrus's FontLab or Macromedia's Fontographer to create a symbol typeface with those graphics. Then both your word processor and layout documents can use the same high-quality versions.

InDesign imports many file formats. If your graphics program's format is not one of the ones listed here, chances are it can save as or export to one. In the following list, the code in italics is the filename extension common for these files on PCs.

The file formats InDesign imports include

BMP: The native Windows bitmap format. .BMP, .DIB
EPS: The Encapsulated PostScript vector format favored by professional publishers. A variant is called DCS, a color -separated variant whose full name is Document Color Separation. .EPS, .DCS
GIF: The Graphics Interchange Format common in Web documents. .GIF
JPEG: The Joint Photographers Expert Group compressed bitmap format often used on the Web. .JPG
Illustrator: The native format in Adobe Illustrator 5.5 through 10.0, is similar to EPS. .AI
PCX: The PC Paintbrush format that was very popular in DOS programs and early version of Windows; it has now been largely supplanted by other formats. .PCX, .RLE
PDF: The Portable Document Format that is a variant of EPS and is used for Web-, network-, and CD-based documents. .PDF
Photoshop: The native format in Adobe Photoshop 5.0 through 7.0. .PSD

New Feature ‚
Spot colors (called spot inks in Photoshop) are now imported into InDesign CS when you place Photoshop images into InDesign. They'll appear in the Swatches pane.
PICT: Short for Picture, the Mac's native graphics format until Mac OS X (it can be bitmap or vector) that is little used in professional documents and is becoming less common even for inexpensive clip art. .PCT
PNG: The Portable Network Graphics format that Adobe introduced several years ago as a more capable alternative to GIF. .PNG
QuickTime movie: For use in interactive documents, InDesign supports this Apple-created, cross-platform format. .MOV
Scitex CT: The continuous-tone bitmap format used on Scitex prepress systems. .CT
TIFF: The Tagged Image File Format that is the bitmap standard for professional image editors and publishers. .TIF

Windows Metafile: The format native to Windows but little used in professional documents. Since Office 2000, Microsoft applications create a new version called Enhanced Metafile. .WMF, .EMF

Tip ‚

When importing any image, make sure Import Options is checked in the Place dialog box (File ‚ Place, or z +D or Ctrl+D). Even if you're happy with the default import options, it's good to see what the import options are so when a nondefault option does make sense, you're aware you have access to it.

Note ‚

InDesign does not support a few somewhat popular formats: AutoCAD Document Exchange Format (DXF), Computer Graphics Metafile (CGM), CorelDraw, and Eastman Kodak's Photo CD. DXF and CGM are vector formats used mainly in engineering and architecture, while CorelDraw is the native format of the leading consumer-oriented Windows illustration program, and Photo CD is a bitmap format meant for electronically distributed photographs.

Issues with vector files

Vector images are complex, since they can combine multiple elements ‚ curves, lines, colors, fonts, bitmap images, and even other imported vector images. This means that you can unknowingly create a file that will cause problems when you try to output an InDesign layout file using it. Thus, when dealing with vector formats, there are several issues to keep in mind.

Embedded fonts

When you use fonts in text included in your graphics files, you usually have the option to convert the text to curves (graphics). This option ensures that your text will print on any printer.

Note ‚

If you don't use this conversion, make sure that your printer or service bureau has the fonts used in the graphic. Otherwise, the text does not print in the correct font (you will likely get Courier or Helvetica instead).

If your graphic has a lot of text, don't convert the text to curves ‚ the image could get very complex and slow down printing. In this case, make sure that the output device has the same fonts as in the graphic.

PostScript files: EPS, DCS, Illustrator, and PDF

PostScript-based files come in several varieties ‚ EPS, DCS, Illustrator, and PDF ‚ and because the format is a complex one, there are more issues to be aware of up front.

EPS

The usual hang-up with EPS (Encapsulated PostScript) files is the preview header. The preview is a displayable copy of the EPS file. Because EPS files are actually made up of a series of commands that tell the printer how to draw the image, what you see on screen is not the actual graphic. Most programs create a preview image for EPS files, but many programs have trouble reading them, especially if the EPS file was generated on a different platform. In those cases, they display an X or a gray box in place of the image (the EPS file will print properly in such cases to a PostScript printer). That's why InDesign creates its own preview image when you import EPS files, lessening the chances of your seeing just an X or a gray box in place of the EPS preview.

When importing EPS files, InDesign lets you control some settings if you check Import Options in the Place dialog box. You can apply Photoshop clipping paths in the file, choose the preview format, convert the PostScript vector information into a bitmap (a process called rasterization ), or embed links to OPI high-resolution source images (see Chapter 31 for details on OPI). Figure 22-1 shows the EPS Import Options dialog box.

Figure 22-1: The EPS Import Options dialog box.

Tip ‚

In CorelDraw 6.0 and later, and in Adobe Illustrator 6.0 and later, be sure to set the EPS creation options to have no preview header ‚ this keeps your files smaller. (In CorelDraw, export to EPS. In Illustrator 6.0 and later, save as Illustrator EPS. Note that Illustrator 5.x's native format is EPS, so don't look for an export or save-as option.)

DCS

The Document Color Separation (DCS) variant of EPS is a set of five files: an EPS preview file that links together four separation files (one each for cyan, magenta , yellow, and black). Use of this format ensures correct color separation when you output negatives for use in commercial printing. These files are often preferred over standard EPS files by service bureaus that do color correction. One variation of the DCS file format, DCS 2.0, also supports spot color plates in addition to the standard plates for cyan, magenta, yellow, and black.

Note ‚

You should not use DCS files if you intend to create composite proof files or in-RIP separations from InDesign ‚ InDesign will ignore the DCS separation files and just use the preview file for output. Only use DCS files if you're outputting separations (but not in-RIP separations). Chapter 31 covers this in detail.

Illustrator

Adobe Illustrator files are very similar to EPS, except they don't have a preview header. There are no special concerns to Illustrator files; just be sure to note the font and color issues noted previously in this section.

PDF

InDesign imports PDF files similar to how it imports EPS and other graphics files (File ‚ Place, or z +D or Ctrl+D). To select a specific page for import, select the Import Options check box in the Place dialog box; you'll then get a new dialog box called Place PDF that lets you select which page to import, as Figure 22-2 shows. It also lets you determine how the file is cropped and whether InDesign places it on a transparent background (as opposed to the paper color).

Figure 22-2: The Place PDF dialog box.

When you import a PDF file, InDesign treats it as a graphic, placing just one user -selected page of the PDF file (if it has more than one page) into your document as an uneditable graphic. You can crop, resize, and do other such manipulations common to any graphic, but you can't work with the text or other imported PDF file's components .

Note ‚

Special PDF features, like sounds, movies, hyperlinks , control buttons , and annotations, are ignored in the imported file.

Other vector formats

If you're outputting to negatives for professional printing, you should avoid non-PostScript vector formats. But they're fine for printing to inkjet and laser printers.

PICT

The standard Macintosh format for drawings, PICT (which stands for Picture ) also supports bitmaps and is the standard format for Mac OS 8 and 9 screen-capture utilities. InDesign imports PICT files with no difficulty, but it cannot color-separate them for output to negatives. Because fonts in vector PICT graphics are automatically translated to curves, you need not worry about whether fonts used in your graphics are resident in your printer or available at your service bureau.

Windows Metafile

The standard Windows format for drawing, Windows Metafile is similar to PICT in that it can contain bitmap images as well as vector drawings. But InDesign will ignore any bitmap information in Windows Metafiles, stripping it out during import. Microsoft Office 2000 introduced a new version of this format, called Enhanced Metafile, which InDesign also supports.

Issues with bitmap formats

Bitmap (also called raster ) formats are simpler than vector formats because they're made up of rows of dots (pixels), not instructions on how to draw various shapes. But that doesn't mean that all bitmaps are alike.

Professional-level bitmap formats

Although InDesign supports a wide variety of bitmap formats, there is usually just one to worry about if you're producing professional documents for output on a printing press: TIFF. (You may also use the Scitex CT format if you're using Scitex output equipment to produce your negatives.) I suggest you convert other formats to TIFF, using your image editor (Corel Photo-Paint and Adobe Photoshop, the two top image editors, import and export most formats, as do other modern image editing programs) or a conversion program like the Mac shareware program GraphicConverter, Equilibrium's Debabelizer for Macintosh, or DataViz's Conversions Plus (for Windows) and MacLinkPlus (for Macintosh).

Cross-Reference ‚

For links to graphics conversion tools, go to this book's companion Web site, www.INDDcentral.com .

Photoshop

InDesign can import version 4.0 and later of this popular image editor's file format. When you place Photoshop files in InDesign, you can control how the alpha channel is imported ‚ be sure to select Import Options in the Place dialog box to get this control. You also can apply any embedded clipping paths and import ‚ or exclude ‚ any embedded color profile.

Scitex CT

The continuous-tone Scitex CT format is used with Scitex output high-resolution devices, and is usually produced by Scitex scanners . If you're using this format, you should be outputting to a Scitex system. Otherwise, you're not going to get the advantage of its high resolution.

TIFF

The most popular bitmap format for publishers is TIFF, the Tagged Image File Format developed by Aldus (later bought by Adobe Systems) and Microsoft. TIFF supports color up to 24 bits (16.7 million colors) in both RGB and CMYK models, and every major photo-editing program supports TIFF on both the Macintosh and in Windows. TIFF also supports gray-scale and black-and-white files.

The biggest advantage to using TIFF files rather than other formats that also support color, such as PICT, is that InDesign is designed to take advantage of TIFF. For example, in an image editor, you can set clipping paths in a TIFF file, which act as a mask for the image. InDesign sees that path and uses it as the image boundary, making the area outside of it invisible. That in turn lets you have nonrectangular bitmap images in your layout ‚ the clipping path becomes the visible boundary for your TIFF image. InDesign also supports embedded alpha channels and color profiles in TIFF files. Figure 22-3 shows the two Image Import Options panes ‚ Image and Color ‚ that apply to TIFF images, as well as to Photoshop and other formats.

Figure 22-3: The two panes for TIFF, Photoshop, and most other bitmap images in the Image Import Options dialog box.

Note ‚

While InDesign offers similar support for Adobe's own Photoshop program, the dominant professional image editor, I recommend sticking with a truly universal format such as TIFF.

The TIFF format has several variations, which InDesign supports. But because other programs aren't as forgiving , follow these guidelines to ensure smooth interaction with others:

You should have no difficulty if you use the uncompressed and LZW-compressed TIFF formats supported by most Mac programs (and increasingly by most Windows programs). InDesign even supports the less-used Zip compression method for TIFF files. You should be safe using LZW-compressed TIFF files with any mainstream program, but if you do have difficulty, I recommend that you use uncompressed TIFF files.
Use the byte order for the platform that the TIFF file is destined for. Macs and PCs use the opposite byte order ‚ basically, the Mac reads the eight characters that comprise a byte in one direction and the PC reads it in another. Although InDesign reads both byte orders, other programs may not, so why invite confusion? Of course, if only InDesign and Photoshop users will work on your TIFF files, the byte order doesn't matter.

Web-oriented bitmap formats

In recent years, several formats have been developed for use on the Web, in the Hypertext Markup Language (HTML) documents found there. These formats ‚ GIF, JPEG, and PNG ‚ achieve small size (for faster downloading and display on your browser) by limiting image and color detail and richness.

Although you can use any supported graphics format for documents you expect to export to the Web's HTML format (InDesign will convert all images to GIF or JPEG when you export to HTML), if you know your document is bound for the Web, you might as well use a Web graphics format from the start.

Note ‚

Because InDesign CS has dropped support for HTML export, there's little reason to use Web-oriented graphics in your InDesign files. If you're using InDesign to create PDF files for access via the Web, or if you're using InDesign to create XML files that will be presented on the Web, you might want to use these Web-oriented formats since they are more compact. Otherwise, stick with the print-oriented ones to get their better image quality.

GIF

The Graphics Interchange Format (GIF) is the oldest Web format. To help keep file size down, it is limited to 256 colors, reducing file size but also making it unsuitable for photographs and graphics with color blends. But its compression approach doesn't lose any image detail, so it works well for sketches , cartoons, and other simple images with sharp details.

JPEG

The Joint Photographers Expert Group (JPEG) compressed color-image format is used for very large images and the individual images comprising an animation or movie. Images compressed in this format may lose detail, which is why TIFF is preferred by publishers. But JPEG can be used effectively even on documents output to a printing press, since you can set the level of loss to none during export.

Still, JPEG is more useful on the Web, where the limited resolution of a computer monitor makes most of JPEG's detail loss hard to spot ‚ giving you an acceptable trade-off of slightly blurry quality in return for a much smaller file size. It's particularly well-suited for photographs, since the lost detail is usually not noticeable because of all the other detail surrounding it.

If you do use JPEG for print work, note that you can provide a clipping path for it in programs like Photoshop. The clipping path lets the image have an irregular boundary (rendering the rest of its background transparent) so you can use InDesign effects such as text wrap.

PNG

A relatively new format, the Portable Network Graphics (PNG) format is meant to provide GIF's no-loss compression but support 24-bit color so it can be used for photography and subtly colored illustrations on the Web.

When importing PNG files, you can choose whether to retain the background color defined in the file or to substitute white ‚ just be sure that Show Import Options is checked in the Place dialog box so that choice is presented. Similarly, you can also adjust the gamma value during import ‚ the gamma is a setting that describes the color range of a device, and to ensure most accurate reproduction, you'd want the gamma setting for the PNG file to be the same as that of your output device (a printer or monitor). Figure 22-4 shows the PNG Settings pane in the Image Import Options dialog box.

Figure 22-4: The PNG Settings pane of the Image Import Options dialog box.

Working with files across platforms

It's increasingly common for people in publishing to work in a cross-platform (Mac and Windows) environment. Even if you do all your InDesign work on one platform, chances are good that you'll receive files created on the other platform. (Most text editing is done on PCs, while most graphics and publishing work is done on the Mac, for example.)

Even with the improved compatibility between Mac and PC (mostly thanks to additions to the Mac OS, which makes it easier to share files with PCs), there are still some trip-ups that you may encounter dealing with something as simple as filenames when sharing files across platforms.

Both Windows and the Mac use icons to show you (and tell programs) what format a file is in. Before Mac OS X, how those icons are created differ between the two platforms, and when you moved files from one platform to another, you could easily lose those icons. But Mac OS X, like Windows and Unix, relies on filename extensions ‚ three or four letters after a period at the end of the filename ‚ to identify the file type and thus display the correct icon. The default on both Windows and Mac OS X is to hide those filename extensions from display.

To see filename extensions in Windows, open any folder, choose Tools ‚ Folder Options, and then select the View tab to get the pane shown in the following figure. (You have to have a disk or folder open to have the View menu.) Uncheck the Hide Extensions for Known File Types option, then click OK. In Mac OS X, there's a similar control accessed from the Finder. Choose Finder ‚ Preferences, then check the Always Show File Extensions check box and close the dialog box.

Note that even though most OS X ‚ native programs such as InDesign automatically add filename extensions when you save, older programs ‚ especially those running in Classic Mode ‚ usually do not automatically add a filename extension. Be sure to add these extensions manually or configure the program to do so for you automatically if it has that option (Microsoft Office 2001 applications do, for example, in their Save dialog boxes).

Other bitmap formats

The other supported formats are ones that you should avoid, unless you're printing to inkjet or laser printers. If you have images in one of these formats and want to use it for professionally output documents, convert them to TIFF before using them in InDesign.

BMP

Like TIFF, the BMP Windows bitmap format supports color, gray-scale, and black-and-white images.

PCX

Like TIFF, PCX supports color, gray-scale, and black-and-white images.

PICT

PICT, the old standard Macintosh format for drawings, also supports bitmaps and is the standard format for Macintosh screen-capture utilities. InDesign imports PICT files with no difficulty.