Custom References and Why They Are Necessary

In our last post, we discussed how you can use our SpotOn! Verify software to compare a measurement of a printing device to a reference such as GRACoL 2013. While there is nothing necessarily wrong with this approach, there is another way to use this information that might give you results that are more useful.

The Problem With Using RPCs

Reference print conditions (RPCs) such as GRACoL 2013 can be helpful as an aim or target to achieve because they are based on a composite of different devices. Therefore they are achievable targets. Because of this, they are generally accepted throughout the printing industry.

The problem is that there isn’t a reference print condition for every printing process. Often you are trying to aim your printing devices to a reference that isn’t for your industry. An example would be printing signage on vinyl using GRACoL 2013, which is an offset on coated stock reference and not inkjet on vinyl.

In Tolerance, But Not Consistent Color

Another issue is that being in spec to an industry standard doesn’t mean that your printing device is producing consistent color. At no time can you actually hit the bullseye of the target to which you are aiming. It’s just not possible. The results will always be a bit off.

What happens if you are off to the left one day by an acceptable amount (within tolerance) and the next day you are off to the right by an acceptable amount (again, within tolerance)? Both prints are within tolerance to the target, but they are off to each other by more. This becomes a color shift that you and your customers can see.

As an illustration of this, we often refer to our Bonnie and Clyde scenario. In this instance, Bonnie and Clyde were two separate printers of the same model using the same inks and substrates and printing the same jobs.

The client was frustrated because when each machine was measured and compared to GRACoL, they both were within tolerance to GRACoL based on industry standards. However, the two printers were visibly not printing the same. How could two printers that were both within accepted industry tolerance of GRACoL be producing such obvious color differences?

Image of Bonnie and Clyde bullseye 1

The answer can be determined by these bullseye charts. As you can see, the two printers are both within a reasonable range of the GRACoL standard. But just because they are both within that range of GRACoL doesn’t mean they are in a reasonable range of each other.

Take a look at this second bullseye chart below in which we compare Bonnie and Clyde to each other instead of GRACoL.

Image of Bonnie and Clyde bullseye 2

In our client’s situation in which they desired their two printing devices to produce consistent color, it would make more sense to measure and compare the two machines to each other than to an industry reference.

Monitoring A Single Printing Device

This same methodology works in a situation where someone wants to monitor a single printing device over time.

Once you have that device where you want it (usually targeting some industry reference like GRACoL), take a measurement and make that your baseline for comparison in SpotOn! Verify. Continue taking measurements comparing each measurement to the new baseline you created. The resulting charts SpotOn! generates will show you exactly how much your printing device drifts away from that baseline you created.

The next step is to establish tolerances for the amount of drift. When the device drifts outside those tolerances, take corrective action (usually maintenance or recalibration of some sort depending on the device) to get it back in tolerance.

Color Management Is A Process

Managing color is a process that needs to be verified on a regular basis. The goal should be to keep color consistent.

To do this, it is necessary to create a realistic baseline or target. This realistic target should be based on how your device prints on a given substrate in your shop.

Monitoring the device to itself in this fashion will result in graphs in SpotOn! that show the variation of this device to itself over time. If you define a reasonably tight tolerance, you can keep your device printing visually consistent over a very long period of time.

Of course, you can make this process more robust by monitoring multiple printing devices to a single reference like the Bonnie and Clyde example. You can also use this method to determine how much of a difference there is when switching to a different substrate. Sometimes you can find that several substrates print similarly, yet others can print very differently.

By making these comparisons using your custom reference, you can determine which substrates will require their own calibration and profile. Plus, you will learn how much substrate contributes to color differences.

Ready For A Demonstration?

If you would like to learn more about how SpotOn! Verify can help you produce consistent color with your printing devices, we would be happy to give you a free online demonstration. Contact us to schedule a date and time!

Image of Trend Graph SpotOn! Verify

How Working With Trends In Verification Software Can Help Control Printing Devices

In our last blog post, we talked about how process control should never stop in your color management strategy. We explained that it’s just as important to maintain your printer’s profile as it is to maintain the printer itself.

To create and maintain a profile, you must incorporate two things into your process: a measuring instrument and some kind of verification software like our SpotOn! Verify to validate the profile.

But how does that work?

Following The Trend

 After you create a profile for your printing device, SpotOn! Verify allows you to measure and validate a control strip printed from your device using the new profile. That measurement is compared to a specified target such as GRACoL® 2013. By comparing the profile to a target, we can verify the accuracy of the calibration and ICC profile.

Another thing that verification software can do is save these measurements so users can track the performance of their devices over time. If you notice that your color is starting to drift, you don’t necessarily have to re-profile your printing device. Instead, you can print the chart, measure it and again compare it against your target. If it’s drifted too far away from that target, then you might consider re-profiling the printer.

Image of Trend Graph SpotOn! Verify

The Answer Is In Consistent Reporting

SpotOn! can also show you how your most recent measurement compares to previous measurements through trend reports. Showing the trend of the printer’s performance over time can help in the overall maintenance of the printing device and help you decide when it’s time to re-calibrate and/or re-profile.

Measuring printer consistency should be developed into a daily routine. The more frequently you measure, the easier it is to understand the behavior of your printing devices and track their consistency over time.

In this way, you are actually taking control and managing your devices rather than being surprised that what you printed last month doesn’t look the same today.  You can’t manage anything if you aren’t taking measurements and evaluating the results.

Image of hands of car driver on steering wheel, road trip, driving on hig

I like to use driving your car as an easy to understand analogy. Keeping your car in its lane is like keeping your printing devices printing consistently.

When customers ask how frequently they should measure their printing device’s consistency, I ask them how long they can close their eyes while driving down the road. I know that’s a bit extreme; but the concept is still the same.

If you want to stay on the road, you have to pay attention to where the car is at all times. If you want your printing devices to print consistently, you have to pay attention (take measurements and analyze the results) on a regular basis. Maybe you don’t have to do this as frequently as you do driving a car, but at least daily should be a bare minimum.

You have to decide how long you want to go without knowing if your devices are printing consistently. Define the frequency and make it a shop policy.

Image of Process Control

Process Control Never Stops In Color Management

Or More Appropriately, Process Control SHOULD Never Stop in Color Management

I had an instructor in a class I was taking say, “You can’t have color management without process control.” I thought about that for a bit and decided he was right.

One of the biggest constants in color management for printing is maintenance. The physical condition of the printer needs to be maintained. The environmental conditions of the printer need to be monitored. And of course, the profile of your printer needs constant process control if you want to achieve consistent and predictable color.

Image of Process Control

You Need A Strategy And Software Is Key

To create a profile and maintain a profile, you need two things: a measuring instrument and some kind of verification software to validate the profile. This is a huge part of process control.

SpotOn! Verify is a flexible powerful tool that helps you clearly define performance and control your print process. The Visual Match Scorecard shows you how visually consistent devices are, and the software provides tracking and trending data to help you print consistently over time.

Image of Bonnie Visual Match

So, Wait. What’s A Profile?

If you’re going to have a good color management strategy with process control, you need to understand what you’re trying to maintain.

A profile is a characterization of how a printing device prints at that moment in time when the profiling chart was printed. It takes into account all the variables that could affect printing such as environment, media, ink, substrate, print speed and resolution – again, at that moment in time.

Changing one of these variables can negatively affect the quality of printing. Therefore, the profile has to be maintained so that it can accurately do its job.

Process Control Through Verification

Let’s say you’ve created a profile for your printer that is giving you great quality print jobs. A couple of months later, you start to see that quality shift in the wrong direction.

Maybe you had to replace the ink or a printhead. Maybe you’re using a different brand of substrate than you were previously. Maybe the temperature or humidity changed in your printing environment.

What can you do?

Before you decide to re-profile the machine, it would probably be worth your time to print out a control strip, measure it against a specified target and use a verification software system to view the results. Many applications allow you to record the status of your printer over time.

By measuring charts and keeping a trend report, you are better able to see the results of how your printer is performing. You may find that the change you’re so worried about isn’t significant enough to warrant re-profiling the printer or you may find that it’s time to re-calibrate the machine.

If you do regular checkups on the profile of your printer and its performance through verification, you are using process control to maintain the condition of that printer.

In our next post, we will talk about how you can use those trending reports in verification software to control printing devices.

If you are interested in a demonstration of SpotOn! Verify, please contact us to schedule a time.


Image of SCCA

How Substrate-Corrected Colorimetric Aims (SCCA) Work in SpotOn!

Recently, we have been trying to highlight various features within the SpotOn! Analyze and Verify software that both users and non-users may not know exist.

One of those features was Visual Match Scorecard. Another is SCCA or Substrate-Corrected Colorimetric Aims and that’s what we would like to discuss today.

What Is SCCA?

Substrate-corrected colorimetric aims refers to a mathematical formula that approximates the L*a*b* values on a different substrate.

According to the Idealliance site when describing SCCA:

“The value of SCCA in the G7 Master process is that it allows a print or proof made on a non-standard substrate to be judged for its “relative accuracy,” i.e. how it would appear to an observer in the absence of a comparison proof.”

That is why SCCA is referred to as substrate relative.

The SCCA Calculator

A while ago, we helped develop an SCCA calculator for Idealliance. It’s free and anyone can access it. You can view the calculator here.

If you take a look at the image below, you can see that in this example of the calculator we are referencing GRACoL 2013 (CRPC 6). The L*a*b* values of the substrate (first column and row under the Analysis chart) are 95, 1, -4.

On the left, we can choose a test chart, like the TC1617, and measurement condition, like M1. In the fourth option down on that left-hand column, we can alter L*a*b* values for our desired substrate. In this example, we changed the b* value to -6 instead of -4.

Back under the Analysis chart in the second column, you can see how the SCCA calculator adjusted the values for CMYK, RGB, and neutral colors based on the desired substrate’s b* value change.

In the third column labeled “Deltas,” you can see the effect of the substrate change on the CMYK, RGB, and neutral patches.

Image of SCCA

SCCA in SpotOn!

From the SpotOn! startup splash screen, you can choose Settings (the wrench and gear icon in the image below).

Image of SpotOn! startup screen

Choose to change the settings of Analyze/Verify in the top menu and choose Tolerance Sets (highlighted in blue below). The ability to turn on substrate relative or SCCA is one of the options in a tolerance set. We suggest picking an italicized tolerance set (system default tolerance sets) that doesn’t have SCCA turned on (G7 Targeted has it turned on) in the list at left and making a copy of it (duplicate). Then you can turn on the SCCA option by checking the Substrate Relative checkbox and Saving that tolerance set with a new name. I usually add SCCA to the end of the tolerance set name so I know that SCCA is turned on for that tolerance set vs. the original where it is off.

Image of Settings Screen

When Should You Turn On SCCA?

When you verify your print and your problem areas are in the whites or lighter colors, it’s often due to the difference between the substrate being printed on and the reference set substrate. Try using the new tolerance set you just made that has the SCCA or substrate relative option turned on.

Image of Substrate Patches

It’s important to note that substrate correction isn’t always the answer, but it can be a powerful tool in SpotOn! just like the SCCA Calculator.

Visual Match Scorecard: A Pictorial Explanation

SpotOn! users are probably pretty used to gauging their print consistency by just the basic pass/fail metric. Perhaps they don’t even venture from this Verify screen (as seen below) where the control strip is measured. Maybe this screen has enough information for them. But maybe not.

We’d like to explain how the Visual Match Scorecard in SpotOn! works at a higher level than just a pass/fail.

Image of SpotOn! Verify Control Strip

This was a verification of a press run, which is why it’s a single row control strip. The pass/fail metric is popular because it can show the press operator problems with CMYK or gray. But it doesn’t show you what the color is going to look like and that’s what makes Visual Match so much more effective. With Visual Match, you are getting an assessment based on the visual appearance between the print and the reference or proof.

For this particular press run, measurements were verified and compared to GRACoL® 2006 over time. Here’s a report of that press run over time using the pass/fail G7® Targeted metrics.

Image of Visual Match Scorecard Blog Pass-Fail Device Graphs GRACoL


Pretty confusing as to how that press run went, right?

Now let’s take a look at a report of that very same press run using the Visual Match Scorcard.

Image of visual match report new


The Visual Match Scorecard allows you to see the results of each measurement in a single metric, making it much easier to compare those measurements. In the report above, the measurement in yellow was the closest to GRACoL 2006.

Since that measurement was the closest to GRACoL 2006, we made that measurement the reference target. As you can see by the chart below, the last two measurements now stand out among the rest as having no visual difference from one another. (See the green bar color in the chart below.)

Image of Visual Match Scorecard Reference 2

So, by using the Visual Match Scorecard feature, we’ve gone beyond just the industry standard pass/fail metric. We’ve included the actual visual appearance into the verification process. The goal is to not rely on a bunch of pass/fail metric values that are great production control metrics (like solid ink density) but don’t inform us about the consistency or quality of the color. While press operators might like this approach for running an offset press, it isn’t helpful from the client perspective of needing their color to match what was printed last time.

Suppose you as a printer were tasked with printing another company’s business card with a brand color. Then three months later, they hire a new employee and need business cards for that person. You print the new cards and the brand color doesn’t match. Obviously, the client is not happy.

Sure, you can run the print with a control strip, measure it and compare it to a target to get a pass/fail. But the customer doesn’t care if the print passes when compared to GRACoL 2006. They care that the two business cards with the company brand color don’t match and are very visually different.

We recently published a blog post where we used a bull’s eye target to display the differences between two printers. A client had two printers of the same make and model. They used both printers to print the same job. Over time, the prints began to look visually different. When compared to GRACoL 2006, both printers passed. But when compared to each other by making one printer the reference point, they were far apart. That’s because the printers drifted in different directions.

Image of SpotOn! Bulls Eyes

On the left is the comparison of each printer to GRACoL. On the right is the comparison between the two printers. The colors represent the colors used in the Visual Match Scorecard.

The point here is that while the individual printers may result in a pass status, they may still be unable to print consistent color compared to one another. If you are only relying on the pass/fail metric to GRACoL, you wouldn’t be able to identify the true visual difference between the two printers. Visual Match Scorecard provides a true visual assessment that helps you better “see” your color consistency. When the Visual Match score indicates a change in color accuracy, you can actually see that difference.

If you would like a personal online demonstration of how Visual Match Scorecard works, please contact us and we will get it on the calendar!

A SpotOn! User Learns New Features For Workflow

Last month, we published an interview with one of our clients who we referred to as “Jane.” She shared how she used SpotOn! in her color management workflow and what she considered essential features. You can read that blog post by clicking here.

We discovered during our interview that while Jane is a frequent SpotOn! user, we had the opportunity to help her with her workflow. There were some features in SpotOn! that she either wasn’t aware of or wasn’t using to her benefit.

For example, we realized Jane was exporting her results into an Excel spreadsheet so that she could share the data with multiple facilities in her company.

Image of Excel Chart Data

We were able to show her through a Zoom meeting (Zoom really is popular right now, isn’t it?) that SpotOn! has a reporting module where you can view a Verify Device Report. It’s easier to read visually and using this feature would save Jane some steps in her color management workflow.

Image of Verify Device Report Multiple Devices-1


In addition, we told Jane the store of Bonnie and Clyde, two identical inkjet printers that were originally calibrated to match the GRACoL® specification. Over time, both printers drifted away from the GRACoL target and then later the two printers were no longer printing the same as each other. The same file printed on both printers turned out very differently and it was quite noticeable.

However both printers were still technically passing the GRACoL specification so how could they be printing so differently?

We showed Jane our bullseye visual. The printers did drift, and they drifted in different directions. So while they both were within tolerance of the GRACol specification, they were far apart from each other visually.

Image of GRACoL Bull's Eye

 Above: Both printers compared to GRACoL.

Image of GRACoL Bull's Eye

Above: Printer 2 compared to Printer 1.

SpotOn! has many features in both Analyze and Verify. And as we have seen, even our most robust users aren’t necessarily aware of all of those features or how they can be of use in your color management strategy.

If you are a SpotOn! user who would like to learn more about the program’s features or if you are considering incorporating SpotOn! into your workflow, contact me to schedule a demonstration.

A SpotOn! User Shares the Benefits of Visual Match Scorecard

It’s easy for the developers and dealers of color management software to talk about the advantages and disadvantages of that software. We can use online demonstrations to explain how it works. We can talk to you about it at trade shows or during onsite training. We are always looking for better ways to explain our features; such as Visual Match Scorecard.

What we can’t do is tell you about the software as it is experienced by someone who decided to invest in it and use it as part of their daily color management strategy. So, we found someone who could.

Jane* is a regular user of our SpotOn! Analyze and Verify software. She also incorporates our Visual Match Scorecard feature into her everyday profiling.

We wanted to tell Jane’s story about her color management process and how SpotOn! is now a part of her strategy to maintain consistent color.

During a recent conversation with her, we realized that no one could tell her personal story but Jane herself. So, in a traditional question-and-answer style, we interviewed her. We invite you to read on and find out more about her path.

The Interview About SpotOn! Visual Match

Q: What kind of processes, substrates, printers, etc. do you use?

Jane: My company prints grand format dye sublimation prints on textiles. We use both the transfer and direct method of printing. We also use UV and latex printers. We have the capability to print on any rigid substrate as well as soft signage.

Q: What are your color management pain points or what issues do you run into most often?

Jane: One word: gray. To be more specific, neutral gray.

People have multiple opinions about gray and throw out the term without actually realizing what they are asking. Gray, by definition, is neutral. This means that there are no colors in it. Many people think that a color that does not have much chroma is gray, when in reality, it is a color.

One of the other problems I have run into is people are stuck in the dark ages of printing where relying on eyes and memory was the way to color manage. We have tools, like spectrophotometers, and software, like SpotOn!, that are driven by data as a means of measuring and analyzing colors, profiles and consistency.

Q: You’re a regular SpotOn! user. How do you use it most?

Jane: Regular might be an understatement. Not only do I use it every time I profile, but also when verifying profile validity. SpotOn! has been a game changer for me as a color manager. I use it to see how close our profiles are within different tolerance sets as well as how the profiles measure over time.

Editors Note: The image above is an actual report from one of Jane’s verifications. Step one is to get as close to an industry specification as possible, using Verify to compare to published specifications like G7 Targeted.

Q: How does the Visual Match Scorecard fit into your color management strategy?

Jane: The Visual Match Scorecard is critical for my position. I measure the profile once I complete it to see how we compare to the tolerances set by Idealliance. Then I make that my reference with the plant, machine, substrate, resolution and a date stamp.

I use this reference to compare the machine/profile/resolution combination to itself and to different machines across the company’s different locations. I have set up a profile verification program for each facility in our company to send me a control wedge along with other control prints and a nozzle check every two weeks. The visual match score is recorded in a simple spreadsheet to track the degradation of each printer/substrate/resolution combination. It helps us visualize possible issues.

Editors Note: The Visual Match Scorecard excels when it’s time to compare today with weeks or months ago when the baseline print was created. In the world of grand format dye sublimation there can be significant drift but maintaining a good visual match score has proven to be sufficient for the work Jane’s company produces.

Q: What’s the biggest color management challenge you have solved using SpotOn!?

Jane: Before I was hired, the most color “management” was having one profile that was created during RIP training many years ago. Our team members used their eyes and many workarounds to create an acceptable output. By managing the color and proving by numbers/science that we are now within industry standards, which they did not know about, was one of my initial challenges.

One of the biggest challenges has been using the data and visual match of our profiles over time to see if we have shifted and are within tolerances. We have been using the data I am able to pull from SpotOn! to prove when I need to re-profile, anticipate potential issues and confirm shifts we are seeing visually through data. I wouldn’t be successful in my position without SpotOn!

Q: What are the biggest advantages in using SpotOn! and Visual Match?

Jane: The biggest advantage of Visual Match is being able to see the consistency of a printer/substrate/profile combination. By tracking the performance of the printers, we are able to understand what variables are causing problems with data rather than relying on our eyes. Managing color across three facilities across the United States is not an easy task. This feature has allowed me to visually see how far the printers have drifted and when to get them back into tolerance.

Image of Jane's trending spreadsheet

Editor’s Note: During our interview, we discovered that Jane was exporting her data into an Excel spreadsheet to share with her different facilities. Since SpotOn! has powerful reporting tools that Jane either wasn’t aware of or just wasn’t using, we realized we had an opportunity to help a client with their workflow. The results of that opportunity will be published in our next blog post.

Q: In your opinion, what is the best feature of SpotOn!?

Jane: Visual Match Scorecard, without a question. It allows color management to go beyond tolerances and actually analyze profiles across multiple platforms. Two printers can hit the same tolerance but not visually match between the two. The human vision is limited and is different for each individual, but the data does not change and is not subjective.

Q: Tell us about your color management journey.

Jane: During my junior year, my school offered a class for printing and photography. I learned L*a*b* and printing techniques. Then in graduate school, I worked at two sister print facilities. Not long after graduation, I had the opportunity to work at a fast-paced fine art printing company to run their print department. Three years later, I took an SGIA Color Management Boot Camp with ColorCasters and decided to pursue color management. Now I am the color manager for three grand format printing facilities in the U.S.

*Editor’s note: Jane is a real person working with SpotOn! in a real-world printing environment. While she does prefer to remain anonymous for this post, we conducted the interview via email by asking questions which she replied with her answers. While her answers were lightly edited for grammar, spelling and punctuation, the answers given here are genuine.

Tricks to Matching Multiple Printers

Calibration of a single printing device is not always the easiest task, and matching multiple printers to one another is an even bigger challenge. One question that has come up frequently, especially with the rise of digital printing, 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 before putting ink on the sheet:

1) Printer gamuts have to be pretty close between devices. This of course has a lot to do with substrate texture and ink texture (rough textured media and/or UV inks both exhibit more light scattering properties due to their roughness vs. solvent on glossy substrates).

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, as you are comparing all patches in the strip to themselves and ranking them on visual closeness.

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.

Tight calibration of the device and the ability to truly recalibrate back to the same known state the device was in when profiled is key. From my experience, the automated “recalibration” process does not always work well in the field. Some RIPs are better than others, but the bottom line is for true recalibration to work successfully it has to be a two-part process. First, you have to achieve the same solid ink value that was in the original calibration, and 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. This is important, because if you can’t fully recalibrate the printer, the original profile is eventually going to be too far off the mark to be useful.


Also consider: very rarely do two of the exact same devices that are exactly the same age print the same color right 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 and achieve 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 to the source reference space. When finished you can compare how close each device is to one another by printing a test chart and comparing the measured results. Now that being said, RIPs that have iterative optimization have a much better chance of achieving a tight calibration between multiple devices than RIPs that can only rely on ink limits, linearization, and icc profiles alone.

You certainly can and should run comparison tests between all your devices (ideally on a single substate 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!

Which Wedge Is Best?

Recently, a color process control manager at a large print production facility 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?”

Great question!

There is a tradeoff between patch count and how effective a chart is at gathering QC information. There is also something to be said for both 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 (like using a 1 pixel eyedropper setting in photoshop to determine the dot percentage in a noisy image). Too few patches and you are not sampling enough colors to accurately model how the device is printing.

I just 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.

The 3-row 2013 12647-7 chart (the replacement for the 2009 2-row chart) was built as 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% GCR values excluding the 3rd color and replacing it with K. This was done because 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.

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, specifically offset printing, 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. This means most metrics are tied to effective control of those ink thicknesses, which is 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.

Bottom line, 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 this should be based on a cumulative relative frequency model (CRF) that evaluates all colors in a chart. In a CRF model, each and every one of the patches is relevant to visual consistency and is being 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 and have continued to get feedback from users who say using CRF and 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! Verify. The trial is free, and our team will help you get started.

Analyze Is Here!


Exciting news! Today, we’re announcing the launch of Analyze, the ultimate weapon for print industry professionals who are serious about printing great color. 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 to help 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, and Analyze also helps users streamline the G7 qualification process and maximize the results over time. We are thrilled to announce this significant step forward for the color industry, and we are ready to help you integrate it into your workflow.

Buy it now, or check out the full press release!