The New Rules for Printing

You don’t get your messages from a beeper, or carry your files on floppies, so stop preparing your print files like you did in the 1990s!

At the advent of desktop publishing, way back in the last century, powerful tools were placed in the hands of people who had no experience whatsoever with the actual process of printing. To say that chaos reigned would be an understatement. Suddenly, printers were being given files built by designers who had no concept of spot colors, bleed, resolution, or even cyan. Printers scrambled to educate neophyte production artists, dictating stringent rules for file submission: No RGB! No JPEGs! No TrueType fonts! Thou shalt submit only TIFFs and EPSs! Thou darest not use Microsoft Word! But now… Welcome to the 21st century! Times are different, and while many people are still following 20-year-old guidelines, the truth is that many of the old rules have changed (well, not that Word thing). Let’s take a look at some modern approaches that might convince you to change some old habits.

Trim and Registration Marks

When we used to output a separate piece of film for each printing ink color, we needed to be able to align those pieces of film on punched clear carrier sheets in order to register the colors for platemaking. To facilitate that process, when we set up jobs for output, we made sure to include registration marks, which are little target-like crosshairs imaged on each piece of film. In addition, we had to include trim marks, indicating the corners of the file’s trim area so that the films could be positioned correctly for platemaking and subsequent bindery work. Boy, have things changed. I can’t tell you the last time I saw film; the industry quickly moved to direct-to-plate imaging over 20 years ago.

When files are submitted for platemaking, they’re imported into an imposition program, which controls the position of each file along with other files for most efficient printing. Imposition software doesn’t rely on trim marks to determine the edges and dimensions of a file; that information comes from internal references in a PDF file or PostScript file. Thus, as long as you build your work to the correct trim size, the PDF itself will inform the imposition software. Including trim marks doesn’t usually present a problem, so long as the additional area generated around the document edges is uniform, allowing the PDF to be correctly centered in its slot on the imposition. But trim marks are rarely required anymore. Unless you’re generating art for silkscreening, there’s no reason to include registration marks; ask your silkscreen printer if they’re necessary. When work is imposed for offset platemaking, the final conglomerate image includes auto-generated color bars and registration marks that provide feedback for computerized print monitoring on press; they’re not used by humans to position film output.

RGB vs. CMYK

The Great Color Acronym Wars of the 1990s have passed. In the olden days, the RIPs (Raster Image Processors) which ran imaging devices did a truly lousy job of converting RGB to CMYK. Consequently, submitting RGB content could merit your output provider giving you a strong talking-to (and billing for the conversion). In the 21st century, modern RIPs perform perfectly good conversions to CMYK, so it’s no longer an issue. However, your printer may still insist that you send CMYK images; if so, you’ll have to perform the conversion yourself. Tip: If you’re asked to provide PDFs, just keep using your RGB images, and then choose a CMYK destination target in the PDF Export options dialog box (Figure 1).

RGB for digital output: Speaking of RGB vs. CMYK, if your job is printing on a digital press such as the HP Indigo, Kodak Nexpress, or Xerox iGen, or a large format output device such as a Vutek or Mutoh inkjet printer, you should ask the print provider if they’ll accept RGB content. Here’s why: the colorants used in digital devices may be called cyan, magenta, yellow, and black, but those colorants use different pigment formulations, which have a wider color gamut than offset inks. Wide-format inkjet devices often add light cyan, light pink, orange, green, and purple inks, too (Figure 2). Consequently, digital devices are capable of printing more of the wider gamut contained in RGB images; when you convert your images to CMYK prematurely, you sacrifice the colors that fall outside the smaller CMYK gamut (Figure 3). Don’t kill those innocent hues! There are other advantages to keeping your images as RGB—they’re 75% of the file size of an equivalent CMYK image, and all of Photoshop’s filters work on RGB images. As with everything, though, ask your printer before you blithely submit RGB content. Some still reject RGB (and in some cases, it’s only out of old habit, not device limitations). NOTE: For more on using RGB images in InDesign before converting to CMYK for output, check out this InDesignSecrets article.

Trapping

If a printer asks you to submit a trapped file, check a calendar. Does it say “March, 1984”? Do you hear the Carpenters’ “Close To You” playing in the background? You may be caught in a tachyon bubble in the space-time continuum. Or you’ve encountered a printer who’s using antique coal-powered equipment and has Always Done It That Way. What should you do? Push the printer to explain why they haven’t been out of the cave in the last two decades. Tell them that disco is dead, too. Run. Find another printer. Software for trapping has been around for over 20 years, so there’s no reason you should have to do anything special in InDesign or Illustrator to compensate for registration issues. In-RIP trapping is the norm now, and has been for many years. It’s a process that rarely needs any human intervention to tweak some settings, and then only in exceptional cases involving metallic inks or complex gradients interacting with multiple underlying colored objects. In fact, printers with digital presses don’t even worry about trapping anymore. We live in wonderful times!

Offset versus Digital

Early digital presses were little more than glorified laser printers, and the quality was no competition for traditional offset printing. In the 20-plus years since the appearance of digital solutions, that gap has disappeared. While the speed and versatility of offset is still a driving force in printing, the quality of output on digital presses such as the HP Indigo rivals that of offset, and the flexibility of short runs can make digital printing a preferred choice. The rise of large-format inkjet output further extends the reach of digital printing. Most printing companies are no longer solely devoted to offset work; to better serve a wider range of customers, many have incorporated digital solutions in their offerings. What does this mean to you? Paper Choices: Because digital presses such as the Xerox iGen and HP Indigo have smaller footprints than giant offset presses, they also have smaller paper size capabilities. The Indigo 5600 and 7800 digital presses can take 13″ × 19″ paper, but the Indigo 10000 has a 29″ × 20″ maximum sheet size. The Xerox iGen 150 can take 14.33″ × 26″ paper. Wide ranges of stock are available for digital presses but, because of texture and humidity requirements, you may find that the 200-lb glitter stock you have your heart set on is not appropriate for digital presses. Spot colors on digital output devices: Most digital presses and large-format inkjet devices don’t have spot inks. The HP Indigo and Xerox iGen have some limited spot toner offerings, including opaque white, commonly used PANTONE colors, and some metallics, but you’ll find that not all print providers have chosen to invest in those add-ons. However, there’s good news: because of the extended gamut of the pigments used on digital devices, there’s a good chance that spot colors will be more faithfully rendered. Lookup tables (LUTs) in the RIPs for PANTONE colors generate optimized values for imaging spot colors. They may not be bang-on, but rendering is likely to be far closer than is possible with the gamut of offset printing inks. If you’re incorporating spot colors in your work, leave them defined as PANTONE colors rather than converting them to CMYK (or even to RGB), and let the device handle the rendering. (There’s one exception to this: see the later section on transparency and digital presses.)

File formats

In the early days of desktop publishing, the limitations printers placed on image formats were based on the sensitive digestive tracts of the RIPs (Raster Image Processor; the computer that converts incoming print information to a language that an imaging device understands). Even something as innocuous as an LZW-compressed TIFF could bring a RIP to a halt, and an overly complex vector piece could prompt the dreaded LimitCheck error (translation: You expect me to process 31,567 points? No way!). We live in enlightened times, and current RIPs have much more capable craws. Native formats: If you’re an InDesign user, you’ve probably long since elected to use PSDs and AI files as artwork. But if you’re still scarred by printer lectures from long ago (“always use TIFF and EPS,” they liked to say), just know that it’s really okay to use the native formats. You can even place a native InDesign file as a graphic in another InDesign file! InDesign knows how to absorb them and squirt out healthy print files. Besides—if you’re submitting PDFs for print, it’s all melted together anyway, with no memory of origin; it’s just all pixels, text, and vectors at that point. Speaking of native files, there’s no need to flatten! (Well, if you have a gigahuge Photoshop file, maybe squish it a little bit.) Both InDesign and Illustrator are fine with live layered Photoshop files. Don’t deprive yourself of the flexibility afforded by layered files. If you’re fearful that a client or printer might mess up your files (or discover your secret recipe for retouching), at least keep a live, unflattened working version in addition to the flattened version. The same goes for Illustrator files; they won’t become any more petite, file size-wise, if you flatten them to a single layer. You’ll still have the same number of objects, and the same number of anchor points. Leave ‘em floating, for cryin’ out loud. JPEGs are not (necessarily) evil: Put down the pitchfork! A JPEG which has been saved only once, using a high-quality (low compression) setting, is just fine (in addition to being petite). If you were to open a healthy JPEG, view it without any editing, and then resave it with a maximum quality setting, it would still be fine. And remember, once it’s baked into a PDF for submission to the printer, it won’t matter how it began life. However, fear of JPEGs is not entirely unfounded: a JPEG that is repeatedly edited and aggressively squished will soon show signs of wear (Figure 4).

My advice? If you receive a JPEG and it’s okay to use as is, then just use it. If you need to edit it in Photoshop, then plan on resaving it as a TIFF or PSD. Then its wonderfulness will be frozen, and it will be happy for the rest of its life. DCS 2.0 (Desktop Color Separations): I recently received a request for a DCS file for an image that included spot color channels. Whoa—what a flashback! Where are my platform shoes? This was for a job that’s running on a digital press that actually has some spot units. I strongly suggest not using DCS if you can avoid it; instead, just place a .PSD containing spot channels into InDesign, and then export to PDF—the correct spot color information is carried through, regardless of the nature of the original image. Font formats: Fear of TrueType fonts dates back to the Dark Ages when RIPs would puke them out; modern imaging devices are font-agnostic. Don’t be afraid to mix PostScript, TrueType, and OpenType fonts; they coexist quite happily. That said, it’s still possible to encounter evil fonts—don’t be tempted to buy the Skid-o’-Fonts from FlyByNightFonts.com. You often get what you pay for. And beware of fonts that don’t allow embedding in PDFs; they’re rare, but they’re out there.

Image Resolution and Transparency

The Holy Grail of Resolution has long been 300 ppi at final size. In other words, don’t take a 3″ × 2″ image that’s 300 ppi and blow it up to 400% in InDesign; its effective resolution is then reduced to 75 ppi (because you made the pixels four times as wide and tall). But there is more leeway than we’ve traditionally insisted, especially when it comes to digital printing. If your hero shot is just 250 ppi at final size, you’re probably OK. In fact, if the image in question is just an accent shot (such as a ghosted-back picture of clouds), you can get by with going as low as 150 ppi or so. This brings up another fun party topic (at least at the parties I attend): Should you scale in InDesign, or Photoshop? Given that you’re bound to encounter small images that must be “embiggened,” you’re going to be forced to grit your teeth and scale them up. My rule of thumb: If you’re scaling up to 125%, you can do it in InDesign. If you have to exceed that value, then do it in Photoshop so you can take advantage of the Smart Scaling features. What about scaling downward? I’d suggest that it’s OK to downsize in InDesign if you’re not going below 75% of the original image size. If you’re going below 75%, do the scaling in Photoshop so you can use the Bicubic Sharper option to introduce a bit of edge sharpening to compensate for the loss of pixels. Clipping paths: Because InDesign (and even PowerPoint!) will accept native PSDs with transparency, there’s rarely any reason to carve out old-fashioned clipping paths. However, I have a few clients whose catalog work involves digital asset management systems, and those DAM systems require that images are stored as EPSs. (EPS files cannot support transparency.) Because many of their products are silhouetted, they’ve found it more cost-effective to outsource that process, and the files come back to them as EPSs with clipping paths. (I envision workers chained to the keyboard, their hands permanently attached to the mouse, clicking their days away. Shudder.) By the way, when it comes to clipping paths, some people wonder: what is flatness? Well, RIPs actually approximate curves with a series of short straight segments, too small to be seen by even the most discerning eye. In Figure 5, you can see flatness exaggerated to illustrate the concept—don’t worry, you’d never actually never see the tiny segments. But because some in the past have overreacted to the notion of flattening, it’s given birth to a persistent old wives’ tale.

People seem compelled to put absurd values in the Flatness field—they have rules like use 0.02 device pixels! That will make my path even prettier! No, it won’t. It will just force the RIP to work harder than necessary to render curved shapes. So, what is the correct value? Nada. If you’re using clipping paths, then just leave the Flatness field blank, and allow the RIP to use its own optimized flatness value (Figure 6). Expanding live Illustrator effects: Another old wives’ tale leads people to believe they should “expand” live effects in Illustrator files. Apparently, they think that simplifies files, or makes them easier for RIPs to digest. Nope. If you expand your effects, you’re only hurting yourself by eliminating the flexibility and changeability afforded by live effects. Expanding will not make a file smaller or better-behaved; in fact, it will often result in a larger file size. The truth is, when you hit File > Print, or create a PDF, the live content is expanded on the way out the door, so the net effect is the same. So stay live. Flattening transparency: When transparent effects were first introduced in Illustrator 9.0 in 2000, printers promptly brought out the pitchforks and torches and proclaimed it to be forbidden dark magic. It turned out that most of the RIPs of the time actually supported transparency, so long as printers changed a few settings, so the mass freakouts were unnecessary. Most current offset print workflows support live transparency, so don’t be afraid to have fun with shadows, glows, and other effects. Some printers or publications may still be using older workflows (or older mindsets), and could insist on flattened PDFs for job submission. In those instances, choose PDF/X-1a; it smashes everything flat, and converts non-spot content to CMYK. However, if your printer lets you send them PDF/X-4, then use that; it lets them flatten the transparency with their systems, which will always result in better output. However, there is sometimes an issue when transparency effects are processed by the RIPs attached to digital output devices (Figure 7). On InDesignSecrets.com, we named it YDB—Yucky Discolored Box syndrome. What causes Yucky Discolored Box syndrome? Digital RIPs color-manage raster content (bitmapped images) differently from vector content (no, I don’t know why). You’ll see this anomaly when transparent effects (e.g., drop shadows, or Photoshop files silhouetted with a layer mask) interact with spot color content. The easiest answer? Convert spot color content to CMYK. You may sacrifice some color vibrancy (especially in bright orange, neon green, and festive purple areas), but that’s far preferable to YDB Syndrome.

Proofing

For many years, printers created contract proofs—color representations of the final printed piece, accomplished by using output film to expose photosensitive color overlays on a carrier sheet (3M ColorKey), or pigments bound to a photosensitive base (Dupont Cromalin and Kodak Approval systems). Now, contract proofs are commonly generated on high-end Epson or HP inkjet printers, displaying color that matches the final print job, including halftones. Many printers these days just provide PDFs to clients for signoff. While this facilitates quick (and cheap) delivery, it’s at the expense of color fidelity—there’s no way to guarantee that a client’s monitor is profiled and calibrated to correctly display color. And PDFs provide no reliable representation of halftones on press, so it’s impossible to predict whether image subjects such as clothing might exhibit moiré when printed. There are digital alternatives: Kodak’s INSITE solution, for example, is considered a reliable representation of press outcome when used on such displays as the Apple Cinema 30-inch monitor or Eizo ColorEdge—reliable color isn’t cheap. But neither is reprinting a job because of disappointing results. If you fear that onscreen proofing isn’t reliable for a particular high- profile job, ask if your printer can provide a physical contract proof.

Advice that hasn’t changed

While equipment and workflows may have become more sophisticated, there is one time-honored rule that still holds true: Talk to your printer! Every printer uses slightly different solutions, and thus may have slightly different requirements for submitted files. Some just want PDFs (and they should tell you what kind of PDF); some want original application files, too. Some support RGB, some don’t. Some welcome live transparency; some don’t. There’s no such thing as too much communication! Open the conversation with your printer early in the life of a print project, and keep up the dialog until the job is out of the bindery. Then you’ll both be happy with the results! …