Constructing a Bullet-Proof Digital File with Illustrator

17 Jul

Making your art work varies from platform to platform.  Although there are commonalities (we’ll review them in a little bit), workflow practices vary depending on the application. In order to keep the size of this entry small enough to keep us out of trouble with our blog-meister, let’s limit this discussion to Adobe Illustrator.  Illustrator is the vehicle of choice for most large format service providers in the creation of print files.

Let’s take a minute to review some of the tips from previous blog posts for successful color management:

  1. Complete all your image work first.
  2. Make sure all of your images are in the appropriate color family for your end product (RGB for web and photo or CMYK for offset printing and large format work reproduction).
  3. All images should be in the same profile.  Examples are: sRGB IEC1966-2.1 for web; Adobe RGB 1998 for photo and Durst/Lambda or LightJet; US Web Coated (SWOP) v2 or Coated Gracol 2006 for most North American offset printing.
  4. Conserve your assets! Make sure you still have unaltered client originals and your multi-layer Photoshop files.

Now, let’s create our working file in Illustrator. The first thing is to check your document color space (File > Document Color Mode > CMYK). Why is CMYK recommended if you’re working in RGB? As we talked about in a previous blog-posting, conversion of postscript values in vector art from CMYK to RGB is a reliable method for maintaining a similar appearance across the spectrum of web and print. It is not reliable in the other direction. (screenshots below in this order: first, CMYK_Black; second, Change2_RGB_Black; and finally, ChangeBack2CMYK).

We will now assign the ICC profile. What we’re going to do is set up Illustrator in such a way as to prevent unintended color transformations (as demonstrated in the previous screenshots). Go to the top menu bar and select Edit > Assign Profile. This will open the Assign Profile dialog box. Check the top radial button, “Don’t Color Manage This Document.” This will prevent Illustrator from changing the color values of any files you link to (“Place” in the File Drop Down Menu) or paste into your document. If you leave Illustrator color management in its default profile (for CMYK that’s generally in US SWOPv2 in North America), each time you paste art from other files into your working file you may, depending on your version of Illustrator, experience unwanted color transformations when you paste or place and embed art into your working file.

Finally, let’s set the value for the Tranperancy Preset. The Transperancy Preset (sometimes referred to as the “flattener preset”) controls the pixel values for any raster objects Illustrator creates from effects like drop shadows, outer glows, and blurs. You want to go to the “Preset:” drop down menu inside the Transparency section of the Document Setup dialog box (File > Document Setup or Alt/Opt+Com/Ctrl+P). You have four options: High Resolution, Medium Resolution, Low Resolution, and Custom. High Resolution assigns pixel values of 300 and is considered the standard for offset printing. Medium Resolution assigns pixel values of 150 and is considered the standard for large format reproduction. Low Resolution creates raster objects with a value of 72 pixels per inch. Low Resolution is considered acceptable for screen printing or web graphics. Remember, these values do not affect images you link to or embed in your art. You can resample your images when you save as a PDF. We’ll delve into that in a later blog posting.

Before you construct your art, you should consider a couple of warnings. First, objects with transperancy effects interact with each other. Be sure you’re fully aware of the capabilities of your service provider before you stack drop shadows, blends, or other effects on top of each other. (Of course, if you’re using BPI, you don’t have to worry about that.) Second, when designing for offset printing, avoid overlaying transparent effects or objects on top of spot colors. Technically, a spot color is supposed to print separate from the normal 4 colors. When RIPS attempt to create a flattened file for color separation, they create image-blocks (sometimes called slices) of raster objects (hopefully you remember the difference between raster and vector) which may vary in appearance from the objects that have a solid spot color value.

Next Time: Let’s talk about InDesign.

PS: Perhaps some of this seems a bit confusing. If you’ve never visited this blog before, perhaps you should visit some of our other postings: “Why What you See Is Not Always What You Get!”; “Basketballs, Meatloafs and Frisbees, Oh My!”; and, “Those Pesky Profiles”.

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