by Sandee Cohen and David Blatner
This article was originally published in InDesign Magazine issue 57 (December 2014–January 2014). Subscribe now!
Some designers who grew up in the days before InDesign were taught to only use EPS or TIFF files. Others, who grew up in the days of the web and smartphone cameras, can’t imagine anything except JPEG or PNG. Is there a best file format to use for everything? Unfortunately, no. Instead, the “right choice” depends on the image, how you’re using it, and a host of other concerns.
Fortunately, choosing a file format to use is not rocket science, and we’re going to lay out the pros and cons of each format for you here.
While there are over a dozen file formats in which you can save your images and graphics, there are some we like to call BFF formats—the ones that work the best with InDesign. You get the most opportunity for control when working with these types of files.
Native Photoshop (PSD) files are the most useful for working with bitmapped images in InDesign. InDesign honors the transparency in the PSD file. It also lets you turn the layers on and off from right within InDesign. You can use Photoshop’s layer comps to turn layers as well as adjustment layers on and off from within InDesign. You can create spot color or bump plates for special print effects. You can even save duotones, tritones, or quadtone images in the PSD file format.
There are only a couple of significant limitations when working with PSD files. First, while you can create a duotone with transparency in Photoshop, you can’t actually save it in any format that InDesign will recognize (it is always flattened with an opaque background). Second, and more importantly: You can create vector text and “shapes” in Photoshop, but if you save your file in the PSD file format, that information will be rasterized (turned into pixels) when you print or export as PDF from InDesign. Instead, if you have a Photoshop document that has vector information (such as type layers), you need to use a Photoshop PDF to maintain that information.
By the way, you may have seen Large Document Format (PSB, or Photoshop Big) files. PSB is a special format that supports files as large as 300,000 x 300,000 pixels. (At print resolution, that’s about 34 meters, or 111 feet, wide.) However, InDesign can’t handle PSB files. In order to place one in InDesign, you need to resample the image to no more than 30,000 x 30,000 pixels and save it as PSD.
Native Illustrator (AI) is the best vector-drawing format for InDesign. Like its Photoshop PSD cousin, the AI file format offers a lot of flexibility. For example, InDesign lets you quickly hide or show the layers of an Illustrator file. When you save as an Illustrator file, make sure you select the Create PDF Compatible File option. (It’s on by default, fortunately.) This adds the information that InDesign uses to display and print the file. Without that setting, you won’t be able to see the file on your InDesign page!
The PDF file format is almost ubiquitous now—you can save it from most programs and you can import it almost anywhere. InDesign is no exception, of course. That makes PDF very flexible and tempting as a file format when working in InDesign. However, make sure you understand the following tidbits when working with PDF.
Photoshop PDF files: It’s rare to save a PDF from Photoshop, but as we mentioned earlier, PDF has an important use, especially for us InDesign users: PDF files maintain the vector information in text and shape layers, where PSD does not. So does this mean you have to save both the original Photoshop PSD file and the Photoshop PDF? No, as long as you’ve enabled Preserve Photoshop Editing Capabilities in the Save Adobe PDF dialog box, you can open the PDF back up in Photoshop as you would the original Photoshop document.
Illustrator PDF files: If you’re only importing your artwork into InDesign, then saving an Illustrator document as a PDF has no real advantage. You might as well just save it as an AI file. That said, there are two reasons you might want to save Illustrator files as PDF. First, if you may need to place the graphic in other programs (Word, etc.), then PDF gives you more options. If you do this, be sure to enable the Preserve Illustrator Editing Capabilities checkbox when saving the PDF; that way you can reopen the PDF in Illustrator without losing any information (you’ve got the complete Illustrator file inside the PDF). A second reason is that you can make the PDF much smaller than an AI file, by turning off that Preserve Illustrator Editing Capabilities checkbox. However, if you do that, you can still place the PDF in InDesign just fine, but you can’t really edit it properly back in Illustrator again later—you lose all your swatches, brushes, groups, live effects, and other goodies inside the original Illustrator file. It’s the closest thing you have to “flattening” an Illustrator file.
Other PDF files: As we said earlier, almost any program can save a PDF, and that means this file format is typically the best way to place information from primitive or out-of-date software. For instance, you may want to use the charts and graphs from Excel in your InDesign layout. Saving those files as PDF is the best way to get the artwork into InDesign. Warning: there may be color shifts, as Excel works in RGB.
Note: If you’re going to be making PDF files from other programs such as Excel, we recommend you not use the Save as PDF command at the bottom of the Mac OS Print dialog box. Instead, install Acrobat Pro and use the Save as Adobe PDF command. This creates a higher-quality PDF, suitable for professional printing.
InDesign makes it easy to repurpose pages from one InDesign document into another: You can simply place one InDesign (INDD) file into another as though it were a graphic! For instance, many companies use the same reply card for all their ads and brochures. Instead of copying and pasting the frames from one document to another, you can just make one reply card file, and then place that file into your other InDesign documents.
While we generally recommend the BFF formats, there are several other formats that are also reasonable to use in professional workflows.
What makes JPEG special is file size: This format isphenomenal when it comes to compressing bitmapped images to th
eir smallest possible size. For example, a 30.2 MB PSD file saved as a low quality/small file JPEG might be only 178 K. However, the key phrase is “low quality”—JPEG is able to achieve these sizes because it’s a “lossy” format. That is, the more you compress your file, the more image degradation you see. When you save a JPEG you can choose a balance between quality and compression. At lower quality settings, you have to be careful of artifacts, such as halos around the edges of objects in your images. At higher-quality settings, you get very few noticeable artifacts, but you can still save a lot of space.
JPEG is also the format that most digital cameras use. You have the choice as to the size and compression of those images. Watch out: The default settings for those cameras can apply more compression than you expect.
We know plenty of people who say you should never use JPEG files for print. Ignore them. There’s nothing wrong with using JPEG files saved at Excellent/Maximum quality for print—you save a huge amount of space on disk (and transmission time across the internet), and it’s extremely unlikely that you’re going to see any image degradation. You can even save CMYK images in the JPEG format. However, JPEG isn’t so good if you’re going to be editing and saving the file repeatedly in Photoshop. It’s really a final-version file format. Also, JPEG doesn’t support Photoshop layers, transparency, spot colors, or vectors; it’s a pixel-only
format designed for photographs.
By the way, there is a cooler version of JPEG, called JPEG 2000, that handles compression even better than JPEG files. That means better quality at even smaller sizes. Unfortunately, InDesign doesn’t support it yet, so it hasn’t really caught on.
While JPEG offers terrific compression for photographic images, PNG is usually a better format for synthetic images, such a screen captures or images that have large areas of solid color (like type on a white background). And, unlike JPEG, PNG files support transparency! We save all our screen shots for InDesign Magazine as PNG files.
For the longest time, PNG was seen as an on-screen-only format, used almost exclusively for websites, interactive PDFs, tablet apps, and so on. However, there is nothing wrong with using PNG for print. Yes, PNG is a pixel-only format, and only supports RGB (no CMYK); but you can save and place high-resolution PNG files into InDesign and they’ll print just as well as PSD or TIFF. So, if file size and transparency are important, consider PNG.