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Tricks to Matching Multiple Printers

June 20, 2017 by bruceb 2 Comments

Calibration of a single printing device is not always the easiest task, and matching multiple printers to one another is an even bigger challenge.

Three Key Things To Matching Multiple Printers

One question that has come up frequently is “what is the best way to profile multiple devices of the same model?” If you are trying to achieve a close visual match between printing devices, there are three key things to consider:

1) Printer gamuts have to be pretty close between devices. This has a lot to do with substrate texture and ink texture.

2) It is necessary to evaluate more than just the worst ∆E value. You need to know how all the patches in a control strip compare in ∆E, not just the worst or the average. When choosing a control strip,the more patches, the better, as long as the chart doesn’t become too large for practical daily use. The more patches under 1 ∆E, the more likely the printing is visually close.

3) You can’t compare to an industry reference, like GRACoL, when visually comparing devices. You have to compare one device as the reference to the other because that’s what you’re looking at in the viewing area. You can’t see GRACoL, as there is no perfect GRACoL proof. But you certainly can see the difference between printer A and printer B. So make printer A the reference when comparing those two devices. Hopefully with grouping tests you can compare multiple devices to one device.

Calibrating The Device

Tight calibration of the device and the ability to truly recalibrate back to the same known state is key.

From my experience, the automated “recalibration” process does not always work well in the field. Some RIPs are better than others. The bottom line is for true recalibration to work it has to be a two-part process.

First, you have to achieve the same solid ink value that was in the original calibration

Second, you have to then create the same curve along the values between 0% and 100%.

Most RIPs do the latter, but few actually do the former during the automated recalibration process. If you can’t fully recalibrate the printer, the original profile is eventually going to be too far off the mark.

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A Single Profile Doesn’t Always Work For Multiple Devices

Also consider that very rarely do two of the same devices that are the same age print the same color out of the box.

I’ve proven this many times when evaluating color output data during calibration sessions. There is no way to successfully use a single profile for multiple devices that aren’t even close to a tight visual match.

My advice is to target the same source reference space (GRACoL as an example) for each device. Then calibrate and profile each device as carefully as possible to achieve as tight a match as the RIP can provide.

When finished, you can compare how close each device is to one another by printing a test chart and comparing the measured results. RIPs that have iterative optimization have a much better chance of achieving a tight calibration between multiple devices.

Run Comparison Tests For Matching Multiple Printers

You certainly can and should run comparison tests between all your devices (ideally on a single substrate all devices can print on) to identify which devices are the closest to one another and group them accordingly.

The point here is to get to know each and every device (it’s gamut, how consistently it prints, etc.). Maybe you get lucky and find several devices that actually are close enough to calibrate using a single profile. Only after going through the process of calibration and evaluating the results can you truly know the color capability of each device.

I have installed many pairs of Epson aqueous printers and have never found two that calibrate the same or profile the same, however, following the process described above will get them to the closest possible visual match.

SpotOn Verify is the ideal tool for comparing the calibration results of each printing device. SpotOn Analyze is the ideal tool for setting ink limits and examining the color differences between each printing device. Try them for yourself!

Filed Under: Color, Color Management, Process Control, SpotOn Verify, Tips & Tricks

Which Chart Is Best For Color Process Control?

January 14, 2017 by bruceb Leave a Comment

Recently, a color process control manager wanted to know if there is a more comprehensive chart available for daily digital color evaluations than an 12647-7 proofing wedge.

He pointed out the IT8.7-4 has too many patches and the P2P51 has too many gray finder patches. Reiterating a thought we’ve all had many times, he asked: “Am I overthinking the value of additional patches?”

Patch Count On Color Process Control Charts

There is a tradeoff between patch count and how effective a chart is at gathering quality control information.

There are two extremes: too many patches and too few patches.

Too many patches on a noisy (grainy, low screen ruling, etc.) printing device can cause unwanted noise in the measurement data. If you have too few patches, you are not sampling enough colors to accurately model how the device is printing.

I dissected the TC3.5 patch set and found it to be lacking in the 3 color grays. There are not many patches and none are G7 compliant gray patches. In my opinion, this eliminates the TC3.5 for any G7 evaluation.

In fact, most of the currently available charts are not very good in the gray areas, especially if you are trying to evaluate G7 compliance. IDEAlliance built the TC1617 to address this lack of G7 gray patches in the IT8.7-4. But even this chart has too many patches for day-to-day evaluations.

A Chart That Is A Good Compromise

Building the 3-row 2013 12647-7 chart was a very good compromise between patch count and patch value.

It has a decent number of patches to effectively evaluate print consistency, which includes G7 compliant gray patches, the typical array of CMYKRGB tone ramps, pastel patches, saturated patches and a good assortment of dirty patches.

These dirty patches were purposely built with CMY values and then with 100% gray component replacement (GCR) values excluding the 3rd color and replacing it with K. Many separations, especially those done with ink reduction products, are made with GCR these days.

It’s hard to beat what’s in that 3-row, 84-patch control strip.

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The 3 Row Control Strip with key patches highlighted.

While considering charts and patch values, it’s almost more important to note the metrics and tolerances we place on these patches for conformance to specifications.

If you look at the metrics we currently use for pass/fail, they are very CMYK printing press-centric.

Commercial print has been the forefront of most industry standard and best practice development. Therefore, much of the data gathering and evaluation is based on printing devices where C, M, Y, and K ink thicknesses are controllable by the operator.

Most metrics tied to effective control of those ink thicknesses are largely irrelevant to the digital world.

We should be asking: “What are we passing and failing?”

For the G7 Colorspace metrics (currently the most stringent), we are evaluating:

  • Substrate – Paper color is good to evaluate
  • Solid CMYK – Very useful to press operators, but not much of a typical image or job is just solid C, M, Y, or K. This makes these patches poor for evaluating digital print consistency, especially visual consistency.
  • Solid RGB overprints – In my opinion, this is more important than Solid CMYK, as overprinted colors are what we see when we look at printed material. Still, these are only the solids, no tints.
  • CMY gray balance and tone – This is very important in controlling and evaluating print consistency, although it’s more important in print processes that lay down individual CMYK inks like offset.
  • All the other patches (pastels, saturated, dirty colors, skintones, CMYKRGB tints) are all lumped into a single metric called ‘All’ and then given a whopping average ∆E of 1.5 or 2.0 and a worst patch ∆E of 5.0 (95th percentile). That’s huge! A virtual barn door to let almost anything outside of grays and CMYKRGB solids pass.

These are not very visually oriented metrics and tolerances. So the big question to ask is what are you evaluating with your chart, or more importantly, what metrics and tolerances are you using to evaluate your chart?

For G7 you could just use a P2P and eliminate the gray finder patches (columns 6-12) because the metrics are really only focused on CMYKRGB solids and the gray patches.

The Bottom Line Of Color Process Control

If we are looking for print consistency, we need to look at establishing new metrics that truly help us determine how visually consistent a print is.

After a great deal of research, I believe a cumulative relative frequency model (CRF) that evaluates all colors in a chart works best. In a CRF model, each patch is relevant to visual consistency and counted within the evaluation.

I have found the 3-row control strip does an excellent job of evaluating visual print consistency when using CRF. I’ve also performed the experiment in live production many times. I have continued to get feedback from users who say using CRF. The 3-row control strip is the best method they’ve found to evaluate visual consistency.

If you would like to see the true power of CRF and real world metrics, try SpotOn Color Verify. The trial is free, and our team will help you start.

Filed Under: Color, Color Management, Process Control, Software, SpotOn Verify

Analyze Is Here!

August 23, 2016 by bruceb Leave a Comment

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Exciting news!

Today, we’re announcing the launch of Analyze. It is the ultimate weapon for print industry professionals who are serious about printing great color.

Simply eyeballing color doesn’t cut it anymore. In fact, it’s a recipe for disaster. It causes lost time, lost customers, and lost profits. Pros know you can’t manage what you don’t measure. Therefore, they collect data and use it to maximize color control.

As a result, G7 experts and in-house color gurus use Analyze to map device behavior, aid G7 calibration, and outperform the competition every day.

Analyze is a powerful addition to print management software that further increases the efficiency of the printing process. It presents detailed color data in a simple visual interface.

In addition, Analyze helps printers improve consistency and increase the accuracy of color calibration for all types of printing devices. It puts process control in users’ hands, helping deliver quicker turn times, reduced ink and paper waste, and improved profits.

In today’s competitive print industry, efficiency and accuracy are the keys to success. Subsequently, Analyze helps users streamline the G7® certification process and maximize the results over time. We are thrilled to announce this significant step forward for the color industry. Meanwhile, we are ready to help you integrate it into your workflow.

Data drives profitable production in any industry; and printers can use it to take control of color and the bottom line.

Most importantly, Analyze is a powerful tool that allows you to streamline G7® calibrations, capture detailed performance data, and anticipate issues before they start. The software enables you to implement process control, make continual performance improvements, and maximize profits. Analyze stops the guessing game by bringing color into the digital age.

Take the wheel. Get SpotOn Color Analyze.

Filed Under: Color, Color Management, News, News and Press, Process Control, Product Updates, Software

Color Management: Get in the Driver’s Seat

August 26, 2015 by bruceb Leave a Comment

Anyone who has been in the printing industry knows how difficult it is to achieve and maintain great color. You need a good color management strategy to do that.

Today, customers constantly demand higher quality and more consistency from their print suppliers. That makes color management a critical piece of any successful print business.

What’s Involved in Color Management?

Color management processes, tools, and workflows vary from company to company. But they are all designed to bring out the best in each graphic, substrate, and printing device.

We need to calibrate printers, presses, and monitors to achieve an expected result. It’s important to streamline repress workflows. Pass / fail metrics are put in place to verify jobs before they go to press.

These steps optimize performance and accuracy when implemented, but they don’t control the effects of time. Running jobs, performing maintenance, and even the weather will impact printed color. But accuracy is a consistent customer expectation.

Process Control Is Part Of The Strategy

Industry leaders control their processes and produce the same high-quality color with consistency over time. They take both color management and profitability to a whole new level.

Not only do they calibrate their equipment and streamline their workflows, they collect performance data over time to decode printer behavior. This enables them to address issues quickly and effectively and achieve superior performance day after day. These pros can anticipate issues before they start and cut crippling color surprises off at the pass.

Accuracy and efficiency are critical to thriving in this industry because high performance is a customer expectation. While color management practices vary between companies, you can maintain peak performance when you apply a process control to any color management system. It’s what separates the best from the rest.

Being right once is good. Printing the right color the first time every time is how 21st century pros blow the competition away. They get in the driver’s seat, turn on process control, and leave the past in the dust. Where are you sitting?

Contact us for a demonstration of our SpotOn Color verification software!

Filed Under: Color, Color Management, Process Control, Software, SpotOn Flexo, SpotOn Verify

Optical Brightening Agents: New Lights for Viewing Booths (Part 2)

July 22, 2015 by bruceb Leave a Comment

In our last blog we discussed optical brightening agents, or OBAs. If you recall, these are the additives that make whites whiter.

Click here to read the previous post.

Optical Brightening Agents Have Issues

OBAs caused issues when they were first introduced to printing substrates. Viewing booth lamps were not designed to activate them.

In addition, spectrophotometer lamps didn’t align with the viewing booth lamps. So they ‘saw’ the paper color with OBA content differently than we ‘saw’ the paper color. The industry began correcting this misalignment in 2009 by updating D50.

The D50 Lighting Condition

D50 has been the long-time standard lighting condition for the print industry. Until 2009, the standard (ISO3664) defined D50 to contain little to no UV radiation, meaning it didn’t quite simulate natural daylight.

This also means prints enhanced with OBAs looked different when being approved in a viewing booth than they did outdoors. Obviously that’s an issue for prints meant to see the light of day.

In 2009, D50 received an overhaul to more closely simulate natural daylight.

UV radiation was added to viewing booth lamps so OBAs would fluoresce, or appear whiter and brighter, during visual approvals. As a result, OBA-rich paper stock looked similar outdoors and in the viewing booth under the new 2009 standard.

A Little History

Change always takes time; so it was a few years before the last of the lamps rated to the pre-2009 D50 standard were purchased and installed. Unfortunately, many people only replace their lamps after they burn out. So although manufacturers no longer sell the old product, many booths still have the pre-2009 lamps. Some even have both the old and new D50 lamps in the same booth at the same time.

The point of having a viewing booth is to standardize lighting conditions and avoid color surprises. Having conflicting lighting conditions in the same viewing booth does exactly the opposite. Speaking of bad ideas, daylight or grow light lamps are not the same as D50 standard lamps. Grow lights (5000K lamps) are not D50 lamps and should never be used in a viewing booth.

Sunshine

New Standard Lamps

The new D50 standard lamps added UV light to viewing booths so visual approvals done inside looked similar to prints viewed outside. This was an important advancement for accurate print approvals on production paper stocks.

Unfortunately, proofing stocks were slower to catch the OBA craze. This caused problems as shops began to replace their old lamps. Press sheets with OBAs and proofing papers without them no longer matched under the new D50 lamps.

As complaints rolled in, viewing booth manufacturers offered a quick fix. A UV filter was placed in front of the lamps to block UV light, and, in effect, converted the new lamps back to the old standard. This allowed proof stocks and press stocks to look the same again because the OBAs didn’t activate with the UV radiation blocked.

This was a Band-Aid approach. The real issue was the proofing stock needed to incorporate OBAs to match the press stock. We are still in flux about how much OBA content proofing stock should have, but today you can purchase proofing and press stock with similar OBA content.

As time goes on, viewing booths and proofing papers will align with the industry’s use of OBAs. Visual approvals will contain fewer surprises, and the lamp challenges experienced after 2009’s D50 upgrade will become a thing of the past. We will all breathe a sigh of relief, turn to our spectros, and begin the journey once more.

Stay tuned for our upcoming blog on spectrophotometers, OBAs, and how D50 and M1 fit into the mix.

Filed Under: Color, Color Management Tagged With: D50, Lighting, OBA, UV

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