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Color Management: The Guru List

More than 20 tips and tricks on wide-format color management from seasoned experts

Big Picture

Getting your production floor in color synch is no easy task. Generally, most print providers will tell you, it’s a lot like herding cats: You’ll get one variable set and then another, but getting every component aligned—hardware, software, media, and so on—is often a daunting, if not seemingly impossible, task.

To aid you in your color-management efforts, we turn to 11 premier independent color consultants—“color gurus,” if you will, all members of The Color Management Group (see next page)—and ask them for some of their top color-management tips and tricks of the trade. In all, they’ve come up with more than 20 invaluable nuggets of advice that should help you rein in at least some of your shop’s color variables.

1. Prepare Printer Before Calibration
Often, color management is started on a device that has not been properly prepared. Before any type of meaningful color measurements can be taken, be sure that the printing device is in good condition. Check that the ink nozzles are not clogged and that all ink-head alignments have been done. It’s tempting to take shortcuts and get started right away—I see that very often. If you discover that the printer is not in optimal condition, your color readings are automatically suspect.
Son Do, Rods and Cones

2. Choose the Right Media
Arguably more than anything else, your media choice has the biggest impact on color fidelity. Choose a quality substrate tested and verified for your printer/ink combination. Substrates not verified or tested for your printer/ink combo can present unique and expensive challenges for color calibration.
Also worth noting: Storing media in the same room as the printer acclimates the media to the temperature and relative humidity of the room. Lots of weird things happen when media is stored in a different temperature and humidity from the printer.
Dan Reid, RPimaging

3. Save Time and Rip Off the Settings
If you’re using a new media that you’re unfamiliar with, open the linearization file and copy the settings. Very often, taking a look at the specially tuned factory settings for a similar media can help save you time when trying to build your own custom calibration.
Ron Ellis, Ron Ellis Consulting

4. Sample Viewing Size and Color
When it comes to large-/grand-format output, it’s not uncommon for small-scale prints to be used as a proof of larger output. Color-management calculations take into consideration the size of the image on the retina of the eye because it can make a considerable difference in the color you see. If one view of a color is a small part of a larger image (as on a proof) and another view is dominated by only a section of a larger image (like a vehicle wrap), then any comparisons drawn will be unwise. For a proof-to-final-output comparison to be valid, they should be placed in such a manner so that the elements on the proof appear the same size to the eye as the elements on the final job.
Steve Upton, Chromix

5. Opening Files in Photoshop
You may have seen the following screens when opening an image in Adobe Photoshop:
• Opening an image with an embedded profile that is different than the workspace (embedded profile mismatch);
• Opening an image with no embedded profile (missing profile).
Note that there is only one common choice in both cases: “Don’t Color Manage.” Many people select this option for fear of doing something wrong (“don’t do anything” seems like a safe bet, given such options). Unfortunately, this is typically a bad choice. At the very least, this option is misleading. There is no such thing as “Don’t color manage.” Even when you select this option, Photoshop still uses your workspace profile to display the color you see. At the very worst, this option implies that you don’t need to think about your color space. The fact is, you do. Avoiding the issue usually results in a mismatch of color and expectations. The best choice in the case of a profile mismatch is, “Use the embedded profile.” This will ensure that your copy of Photoshop will pick up the same color table that was used to display the image when it was created.

In the case of a missing profile, if you don’t know what the color space should be, the best choice is, “Assign working space.” If you do know the color space, however, and that color space is different than your Photoshop defaults, the best choice is “assign profile.” For example, if you see message number two when opening a CMYK image in Photoshop, and you want to see what that image would look like on a Gracol-calibrated press, assign the Gracol ICC profile and then click “OK.”
Marc Levine, The Color Management Group

6. Maintaining Systems Over Time
The challenge is maintaining a system consistently over time. Because media, inks, and even printers change over time, a good system must compensate for this variation. Daily, real-time re-calibration provides a solution. Test charts and a test page with images provide the data and visual references for evaluation. Just load the media and print the test form. Compare this print to the standard. Visual comparisons are often a sufficient test if conditions have not changed dramatically.

If small corrections are required, the printer can be re-calibrated, while larger changes and weekly numeric performance evaluations would require use of the test chart and measurement with a spectrophotometer. This can be done while the current job is running, producing an updated profile by the time the next job is output.
David Meyers, Meyers Prep

7. Use the Best Quality Monitor You Can Get
Monitors are your window to the digital world. LCDs are great now that the technology has matured enough for serious color use, just be sure to buy a good make. Your “working area” should be measured in pixels, not inches. I found that my first 17-inch LCD was as usable as my old 22-inch CRT. Now that larger screens are readily available, I certainly do appreciate the extra space.

And, of note: Although a thing of the past, older, high-end CRTs can be good as long as they’re not worn out. Keep in mind that a CRT produces its image by bombarding phosphors so the imaging area does eventually fade and luminance falls; so, eventually, a decent black is impossible to achieve.
Neil Barstow, colourmanagement.net

8. Use L*a*b* for Controlling Brand Colors
Use L*a*b* to achieve best possible color matches for spot/brand colors. First, make sure to build your files correctly—if you have a spot or brand color, define it as such in the art file. If you’re printing the file from a desktop application, make sure to send process and spot data—don’t convert to process. Most RIPs come with Pantone libraries and these will generally yield pretty good results for PMS colors. But if these matches aren’t close enough, use a spectrophotometer and measure the desired color. Override the spot-color recipe in the RIP with the measured value and fine tune from there, if need be.

Also, be careful what you are comparing to—I see lots of people comparing output to old and outdated Pantone Guides. Make sure your guides are current; if they are not current, replace them or print your own spot-color guides!
Dan Gillespie, ColorGeek

9. RGB ‘Driver-Based’ Profiles
If you’re profiling your inkjet printer via the manufacturer’s driver and using a third-party media, don’t assume that the media vendor’s recommendation for media/paper setting is the best choice. Print the profile chart through all the relevant media types (with color management disabled), create the profiles, and analyze all of them. Print a test image that detects over-inking and “smoothness,” and use a profile-analysis tool such as Chromix ColorThink Pro, X-Rite Monaco Gamut Works, Alwan Color Pursuit, etc., to check for the largest gamut volume and the most linear behavior. Often, the media vendor’s recommendation isn’t necessarily the best one.
Terry Wyse, WyseConsul

10. Matching to Sheetfed
Matching wide-format prints to sheetfed prints can be tricky, even after ink limiting and profiling. Sometimes the issue is that the color of the inkjet ink is too different from conventional printing inks to make it easy to match a corporate/brand CMYK spot color without doing a color transformation on each file. Other times, the adjustment to get the brand color kills the other details in the job.

Not all RIPs allow this, but if you can manage individual channels of ink (c, m, y, k) during ink limiting, you can select the closest match to CMYK L*a*b* colors specified in Gracol/SWOP guidelines (same as the ISO Standard). Print a CMYK step wedge and measure the hue angle of the heaviest patch, adjust the density/Total Ink Limit of this patch to get the closest hue angle to that required. For instance, the required hue angle for cyan is 233 degrees. Once the ink density/hue-angle adjustment has been made, this will be an excellent base to G7-calibrate your printer, and you will have a much better chance of getting a “shared visual match” between wide-format and sheetfed corporate/brand colors. This will be an excellent base on which to build a profile.
Dan Wilson, Prepress I.T. Limited

11. Temperatures for Solvent Media
Heat has advantages and disadvantages when printing on solvent media. Advantages include: more ink load (larger gamut), faster drying times, and better adhesion. Disadvantages include: head strikes, wear on the print heads, and nozzle clogging.|

Here is how I find the maximum amount of heat that a media can handle (doing so will help protect you from head strikes): Load the media and set the heaters to the highest temperature. Sit level with the height of the media laying on the platen. Watch for when the media starts to rise and ripple. When it does, check the current temp on the heaters.
—Stephan Marsico, Digital Color Concepts

12. Watch That Paper Color
Be aware that brightened, super-white media can fool the instruments you use (and make your results have a yellow cast). Make sure to turn your UV filter on if the material is bright bluish-white.
—Ron Ellis, Ron Ellis Consulting

13. Hide Network Printers
When working with one or multiple inkjet printers on a network, it’s a good idea to “hide” the printers that are driven by a color-managed RIP. Most printers broadcast their presence via Bonjour and Windows Plug and Play. Often, users will unwittingly add printers to their workstations. By turning off these printer broadcasts (usually there is a simple Web interface for this purpose), e-mails and other inappropriate files will not then mysteriously print on wide-format inkjets, onto very expensive media.
—Son Do, Rods and Cones

14. Calibrating Challenging Media
Uncoated papers, canvas, mesh, and fabrics are the most challenging to use. These substrates require careful calibration to ensure the best looking output. If you find that you have to reduce the total area coverage (TAC) to less than 200 percent (from 400 percent), consider dropping the printer resolution to reduce the quantity of ink laid down. Consider using a densitometric method for linearization (or calibration) to achieve perceptually dark-to-light gradients of each printer colorant for low-color-gamut materials.
—Dan Reid, RPimaging

15. Average, Average, Average!
When profiling a wide-format inkjet printer, it’s not a bad idea to print several profiling charts across the width of the device, measure all of them, and then average the results before creating the profile. Taking it a step further, compare the averaged results to the individual results to get an idea of how consistent your inkjet device is across the width of the printer (you may be in for a surprise, and not a good one!).
 

To eliminate your measurement instrument as a possible variable, measure the same chart several times and compare the results. If you find, for example, your measurements vary more than about 1 delta e, the instrument, or your technique if it’s a handheld device, might be suspect as well. Start with a minimum of three profile charts and possibly up to nine (three wide x three deep) for a good average.
—Terry Wyse, WyseConsul

16. Monitor/Display Screen Setup
Accurately set up your screen to internationally accepted standards:
• White Point should be targeted to visually match your print viewing environment by iteration. Note that, even with D50 viewing, we normally find that targeting D65 matches better than D50, as a starting point.
• Black level: If you have this option, start at Minimum, Neutral.
• Tonal Gradation: L*(star), or, if that’s not available, Gamma 2.2 (yes, even on a Mac).
• Avoid cheap calibration solutions and visual processes.
• Verification: Note that comparison of your screen image to a printed “Verification Image” (e.g.—a certified proof of a good test image) can be a very useful aid to deciding on your final targets for calibration, i.e.—white point (color temperature) and white luminance. It is a great confidence boost to know for sure that your screen can match the accurate proof print. “Verification Image” is our name for a quality print known to be a true rendition of the file’s content.
—Neil Barstow, colourmanagement.net

17 Calculate Your Own Delta e
It is actually easy to create a spreadsheet to calculate delta e CIE L*a*b*: Measure two colors. Write down your L, A, and B values. You now have L1, L2, A1, A2, B1, and B2. The formula is as follows: √ [(L1-L2)2 + (A1-A2)2 + (B1-B2)2]. In Excel, square root is denoted by SQRT, and squared is ^2.
—Stephan Marsico, Digital Color Concepts

18. Use Bigger Patch Charts
If you have achieved exemplary color calibration (linearization) and ideal ink limiting, then consider creating a new ICC profile with 3000+ color patches instead of the standard IT8/7.4 or IT8/7.3. An ICC profile from 3000+ color samples provides improved color accuracy from the increased data sampling. 3000+ patch ICC profiles do not work well with output that has improper ink limits and/or a visible color bias.
—Dan Reid, RPimaging

19. Photoshop for Image Assessment
Learn how to use Adobe Photoshop tools such as “Levels” to judge a file’s quality and ensure that scans and capture files are being made correctly and when moved, re-saved or edited, that the data stays intact. We recommend users retain full range of tone and color as long as possible in the process to respect the original art—if that’s the desired look. Since we all know that printing is improving by leaps and bounds, it’s inadvisable to discard image data (for example, by reducing saturation or converting to a small colorspace) just because an image is destined for a low-quality publication or print process. Make a copy first, save the original.
—Neil Barstow, colourmanagement.net

20. Inkjet Gamut Limitations
Gamut limitations in inkjet output can sometimes surprise people. Many assume that the inkjet gamut is always larger than a typical printing press (such as shown with a Gracol profile). While many inkjets print more saturated mid-tone colors, when it comes to shadow colors they may not be able to precisely reproduce the darker browns and greens found in many images. This can result in unexpected color shifts and sharp transitions. To take advantage of inkjet’s capabilities, ask for files in RGB spaces like Adobe RGB, and to maximize dark color gamut, choose your media carefully and convert color to your custom profiles judiciously.
—Steve Upton, Chromix

21. Hire Some Help
A consultant can train and quickly get you up to speed. Just make sure you outline your expectations and what you need to accomplish. Very often they can get you there quickly—and teach you things that would take weeks or months to learn on your own.
—Ron Ellis, Ron Ellis Consulting

22. Archiving the Master Image
Where space permits, archive your raw files or high-bit (16-bit) originals—and also your full-size 16- or 8-bit layered .psd image files. At output time, working on a flattened duplicate, optimize your output files to suit the print destination and—importantly—work on your compatibility with the others in the image chain—be they photographers, designers, agencies, or print houses.
—Neil Barstow, colourmanagement.net

More on Color?
Please let us know if you’ve found these tips helpful, or if there are specific color topics you’d like more information on. Of course, your own color tips are welcome as well. Send any color-management notes to: bigpicletters@stmediagroup.com (subject line: color mgmt).

Get Your Guru Here
The following 11 color-management experts chipped in tips and tricks for this article, and were willing to share their expertise with readers of The Big Picture. We’ve provided names, companies, websites, and locales for each:
• Neil Barstow, principal, colourmanagement.net, Hove, England;
• Son Do, co-founder and technical officer, Rods and Cones
(rodsandcones.com), Santa Cruz, CA;
• Ron Ellis, principal, Ron Ellis Consulting (ronellisconsulting.com), Stratham, NH;
• Dan Gillespie, president, ColorGeek (colorgeek.com), Lancaster, PA;
• Marc Levine, director of business development, The Color Management Group (colormanagement.com), Stoneham, MA;
• Stephan Marsico, owner, Digital Color Concepts
(digitalcolorconcepts.com), Charlotte, NC;
• David Meyers, owner, Meyers Prep (meyersprep.com),
Strongsville, OH;
• Dan Reid, president, RPimaging (rpimaging.com), Tucson, AZ;
• Steve Upton, president, Chromix (chromix.com), Seattle, WA;
• Dan Wilson, principal, Prepress I.T. Limited (prepress-it.com),
Dublin, Ireland; and
• Terry Wyse, principal, WyseConsul (wyseconsul.com), Charlotte, NC.

In addition, we’d be negligent if we did not acknowledge the help of The Color Management Group (colormanagement.com) in helping put this information together. Founded in 2003, The Color Management Group, based in San Jose, California, is a worldwide consortium of premier, independent, consultant-based resellers and their Silicon Valley distributor who share technical information and work together to conduct marketing activities. Members provide pre-sales assistance, product sales, integration, training, and technical support of color-management solutions and G7-related technologies. All 11 consultants referenced here are members of The Color Management Group.


 

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