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![]() Color Management Basics, Part 3
By Ray Weiss, Digital Imaging Specialist, SGIA
Remember the red sports car from Part 1? There is a lot more happening underneath that red paint.
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If you want to go fast around the track, you better have good tires, a well-tuned suspension and a dialed-in motor. If not, you may not even make it around the track at all, or you may crash into the wall. Not unlike your car, not having a good process for your color management can leave you tweaking colors or reprinting jobs. Having a process to follow is critical for consistent and repeatable color, and using the color management pyramid as the basis is easily introduced into your production environment. An important point to note is the importance of documenting what you are doing. Don't try to remember what the humidity level was four months ago, or what rendering intent you use for a particular customer and their jobs. Have a notebook or spreadsheet for each device with notes on the settings and environmental conditions so that you are able to track each step of the pyramid. That said, let's jump right into the first level of the pyramid.
Ambient or Environmental Conditions
![]() Lastly, all printers should be on some sort of surge protection. Use an amp meter to test your electricity source and make sure that it falls within the manufacturer's range. Many manufacturers will have recommendations if you are trying to incorporate a battery backup for your printer, so make sure you know the electrical draw the printer requires and purchase enough battery to allow for a controlled shutdown in the event of a power outage. Some impacts of a poor environmental condition will be noticed in ink absorption and droplet placement. Too high humidity and the ink may not dry as quickly, and too low humidity can contribute to nozzle clogging. High static electricity can actually cause ink droplets to veer off course and not fall where expected, which is an obvious problem for quality and color. And don't neglect proper storage and care of your media when considering environmental conditions. Roll materials should never be stored flat on a shelf as a flat spot will be created which will definitely impact print quality.
Printer and Media Calibration
RIP and Print Settings Most RIP manufacturers will have default settings based on what they have decided works best with their software, printer and media configuration. That doesn't mean you shouldn't experiment with the different settings to see what works best for your application. This is a good point to reiterate the importance of note taking. As you experiment with the different settings, it will be crucial to have good notes so that you can recall what settings worked best for which application. I would highly recommend that you put together a "sample" or "test" print (if you don't want to create your own, many of the RIP manufacturers will have some quality test print that you could use). Ideally this control print will have a variety of images both vector and raster, and should reflect the type of work that you typically do in your shop. Have a series of spot colors (I would obviously focus on those that you run the most or that give you a challenge) and a gray ramp (neutral grays from 0 to 95 percent). You also should find a target patch set such as the IDEAlliance 12647-7 Control Wedge 2013, or make your own that you will measure to establish a standard. The goal with the patch set or wedge is to have something that you can use as a tool to verify that your printer is giving you consistent and repeatable color. If you want to see a suggestion, SGIA offers a control print that is used during color management workshops. Find it at https://www.sgia.org/resource/other/sgia-control-image. Most of the other settings at this stage are pretty self-explanatory: resolution (is it printing 600x600, 720x1440, etc.), pass count (how many times does the print head go over an area - this is a good way to hide when a nozzle is missing), and overprint (basically used for backlit applications). Light Ink Transitions refers to where the light inks will end or taper off and the primary colors take over (light cyan and cyan, for example). I also like to set the rendering intent at this stage. This is something that can be changed later and not affect the profile itself. I set the rendering intent to see how it affects my color output throughout the later stages of the pyramid. A rendering intent is a way for the software to take colors that are out of the printer gamut and bring them into gamut. Typically relative colorimetric using black point compensation is the rendering intent most commonly used for printing in North America and Europe. Some of the impacts that are noticed are overall gamut, print speed (number of passes) and ink consumption. Watch out for fuzzy or a grainy appearance, poor dot pattern, banding and trouble hitting/matching colors.
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Primary Ink Restrictions Before moving on to the next step in the pyramid, let's take a short detour for those that do not have the resources (yet) to take the plunge into the world of spectrophotometers and creating their own profiles. For those shops, it would be helpful to use the first three steps of the pyramid as the process that you will follow to make sure that your printer is printing as consistently as possible. After you have done that, print out a color chart, such as a Pantone® Coated chart from your design software. Now you have a reference - a manual chart that you can use to select colors when working on customer's files. Because you have printed the chart (and you should have one for banner and vinyl - and if you laminate, one with and one without lamination), you now have a physical representation that will let you know how your printer reproduces the color that you can see printed on the chart. This is not a perfect solution, but it is one that I have seen a number of shops use with success to help them with their color reproduction. The downside of this system is you will have to print these charts a few times a year to account for your printer's color shift that will occur over time, and particularly over different seasons; remember the summer high humidity and the winter low humidity. And this system is only good for those colors that you have printed with your chart. This isn't a perfect solution, but it can be a stop gap measure that you would use until you can acquire a spectrophotometer.
Linearization Linearization impacts gradient smoothness. If you have an uneven distribution of ink (pre-linearization) you will definitely see an improvement with a good linearization curve. Also affected are tonal detail, gray balance/neutrality and loss of shadow or highlight detail.
Total Ink Limit Total Ink Limits impact color gamut (though not as much as the Primary Ink Restriction step), gradient detail and quality, tonal detail and ink consumption. Some of the symptoms that will alert you to this are over-inking artifacts, loss of shadow or detail in highlights and inconsistent color. The same adage applies here as it did in Primary Ink Restriction - more ink does not equal better quality. This would be a good time to print your sample or test image to look for any of these issues before moving on to the next step.
ICC Profile The actual profile you will build at this point is created by printing a range of various color patches. In this case, more patches do equal better quality. Most RIP software will give you options for number of patches. Though it takes a little more time, more patches will give you more even color and thus will give you better quality. Once you've printed the patches, it is time to take a spectral measurement. I like to imagine the profile as a three-dimensional space of a fixed size with color/data information. The more patches you read, the more data points and the less extrapolation that needs to be done from this three-dimensional space to match a particular targeted color. The last step in creating the profile is GCR (Gray Component Replacement) or UCR (Under Color Removal). Suffice it to say that the goal is to tell the RIP where to start black replacement in component color areas (CMY+K). If you have a printer that prints very small, fine dots, then you can start the black ink earlier - and therefore use less CMY which will save you in ink consumption. This is another great use for your sample image. Try starting the black ink earlier and earlier until you begin to see peppering, particularly in the highlights such as skin tones. Once you see that, you will know to back the black ink off a little, and you should have a good setting. Most RIP software will have a recommendation, but don't be afraid to experiment. The ICC profile (along with GCR) impacts color accuracy, gray balance/neutrality and ink consumption. Some of the symptoms that will alert you to a problem are heavy ink consumption, particularly dependent upon the GCR setting, and metamerism, a color shift caused by different lighting conditions. Using more black in the neutral colors will help to minimize the effect of metamerism. Now you have it - the complete Color Management Pyramid. Remember that without a solid foundation, you can't build a good profile. Following these steps will send you down the road to more consistent and repeatable color. Stay tuned for Part 4 of this series where we'll explore RGB versus CMYK workflows, setting up your Adobe software and monitor profiling and soft proofing. Ray Weiss, Digital Imaging Specialist for SGIA, joined the Association in 2014. He provides solutions and technical information on digital printing as well as digital equipment, materials, and vendor referrals. He oversees several workshops at SGIA along with the association's digital equipment evaluation program. His 25+ year career in the graphics industry began with a typesetting and prepress business in Washington, DC, which grew into an offset print operation in Maryland. He then moved into wide format sales, training, support, and service. Ray has extensive experience in color management and worked closely with the Smithsonian Institution to implement a color managed workflow in their Exhibits department. This article appeared in the SGIA Journal, July / August 2016 Issue and is reprinted with permission. Copyright 2017 Specialty Graphic Imaging Association (www.sgia.org). All Rights Reserved.
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