What's the difference between saving a vector as .AI and saving as .EPS

Question

Is there any benefit to saving as AI? I know that EPS can be opened in many programs, but AI, I think, would only be opened in Illustrator. Should I bother saving in AI?

Answer 1

.ai

Contains:

• Native Illustrator content (unflattened) - used when file is reopened in Illustrator
• PDF 1.4 content (unflattened) - used when file is opened or placed anywhere else*

*In the Illustrator Options dialog that appears when you save a native .ai file, a checkbox called Create PDF Compatible File, marked on by default, determines whether the PDF portion of the file is included when the file is saved. With the option turned on, your file size grows, but the file can be read by apps like InDesign and Photoshop. Turning it off will chop the file size in half (and speed up save time), but the file will only be able to be reopened in Illustrator.

.eps

Contains:

• EPS content (flattened) - used when file is opened or placed anywhere else
• Native Illustrator content (unflattened) - used when file is reopened in Illustrator*

*Remember that Illustrator saves its native content for the version that you specify. So if you save your file out as an EPS file compatible with Illustrator 8, then the native Illustrator data that is saved along with the file is Illustrator 8 data — a format that didn't support transparency. Also, saving back to previous CS versions mean you're going back to the pre-new text engine versions, and text won't be editable, even if the file is reopened in Illustrator CS2.

source

The upshot is, when saving from Adobe Illustrator, both .ai and .eps formats include the fully editable native Illustrator data.

There are two advantages of saving to .ai:

1. Decreased file size, especially if you don't select the "Create PDF Compatible File" option.
2. .eps is a more generic encapsulated format — many different applications can save .eps files. So by saving to the .ai format you know that the file was created in and saved from Illustrator and will be fully editable. If your .eps file loses its metadata you won't know if it has native Illustrator content or if it simply contains vector/bitmap data created in another application.

Of course, the advantage of saving to .eps is that it is a more portable format. It can be embedded in a wider variety of non-Adobe documents and applications.

Answer 2

There's a great deal of opinion and frankly false information circulating on this topic.

It's pretty safe to say that EPS, being Postscript based, is an obsolescent format just as Postscript is obsolescent. It served the community well back in the day, but it's long been overtaken by PDF and AI. EPS has almost no place in a modern graphics workflow and is best avoided except in very specialized cases. Bar code generators commonly output EPS, and it's an excellent format for that kind of thing, but that's not something you'd typically do in Illustrator, even if you're in the packaging industry.

Craig Kirkwood on Pixel Therapy posted a good summary of the situation here. See also Mordy Golding's comments on this thread in the Adobe forums.

EPS is Postscript based. Illustrator after AI8 is not. Versions since AI9 replaced Postscript with a superset of PDF 1.5, which supports transparency (Postscript does not), and other capabilities such as 3D and color blends that Postscript knows nothing about.

Illustrator long ago became so dominant in the market that it was in the best interests of other graphics program makers to support the format, and most of them do. Corel Draw, often used by small T-shirt and engraving shops, is a horrible exception, since it has its own ideas even about EPS and frequently messes up both import and export of that format.

An AI file is readable across the Adobe Creative Suite applications, and can be placed directly in Flash, InDesign, After Effects, Premiere Pro and Photoshop. Layers are retained, and for example can be turned on and off from inside InDesign using the "Object Layer Options" function. Quark Xpress now supports direct placement of AI files and PSDs, something they had no option but to offer in an effort to stay competitive in the marketplace.

So there are many benefits to saving in AI native format as opposed to EPS. The graphics world has been moving beyond the restrictions of Postscript for years, and that trend shows no signs of slowing down.

Many print shops have already moved from Postscript RIPs to direct PDF RIPs using the Adobe PDF Print Engine, which retains transparency and generates no intermediate Postscript code. The advantages in speed and simplicity for the print provider are large, and all of the major RIP providers (Agfa, Heidelberg, EFI and so on) now offer it. The APPE/JDF (Job Definition File) workflow will be pretty ubiquitous within the next five years.

Answer 3

And EPS stands for Encapsulated Post Script and isn't a file format as much as it is a file container. An EPS can all sorts of data. It's been a while since I've done much AI work, but I believe you can save it as a more generic EPS, which any other decent DTP application with PS support should be able to open, or you can save it specifically as an AI EPS, which I believe will also contain the AI-centric information as well. The con of the latter is that it's likely a larger file size.

In general, I think it's a good idea to treat EPS files like JPG files when you're working with raster images. Always keep the original source format file you are using, and then, as needed, export/make a copy of it as an EPS for distribution or sending out for prepress. But always keep your original .AI as well.

Answer 4

An answer from a different perspective:

In our design shop, when we create a logo with text, the original is saved as an AI with live fonts.

When the logo is approved by the client, the letters are turned to outlines (so the logo can't be screwed up in another application by having a font missing) and we save that as the EPS version.

We always know to use the EPS as the "final" version of the logo, while the AI is the "original," in case the company name changes or amends or we need to update a phrasemark or deck or something.