Troubleshooting Color: Output Color Profiles

More than once I have been asked: "OK, so the color is wrong, how do I make it right?"

Troubleshooting CMYK color can be a pain, because there are often many places the problem could be lurking, and changes made in one, may inadvertently alter the output based on info from another. So in this five part series, we will look at five important steps to troubleshooting a color managed system, or colorimetric tuning.

As you all know, a color management system is usually broken into five parts:

1. Source color space
2. Media parameter setup
3. Source color space designation
4. Output color profile
5. Output calibration set

Let's take a look at number four on our list - Output Profiles

One of the first things to be aware of is your own expectations. People often assume that printer profiles should make everything match but a printer profile is just a measurement of what a combination of printer, ink and paper can reproduce.

Different types of printers and ink sets will produce different color gamuts. Different papers and surface textures will influence both color gamut and appearance. Matte papers always look flatter than gloss papers for example. Also the color of the paper white has a big influence. A warmer paper color will give warmer grays and skin tones than a cooler more blue-ish white paper.

Media with Optical Brightening Agents (OBAs) often require custom profiles to account for the fluorescing factor.

The combination of the ICC output profile and the calibration set allow the RIP to adjust for the white point, imaging characteristics and d‐max capability of the output media. For standard color, the output profile may have less effect on color than does the calibration set and other factors described previously. Bypassing conversion always ignores output profiles.

In most cases, the standard Fiery output profiles for Plain, Coated Matte & Coated Gloss may be suitable for most customers on most media. These are based on GRACoL standard, therefore are neutral grey by default.

After machine setup and linearization, the machine should be calibrated on the target media and test prints made using the applicable standard Fiery profile. Only if results appear unacceptable or sub-optimal should the time be spent to create custom output profiles.

If a custom output profile is necessary, the standard 928 patch target seems to provide suitable results on most printer/copiers. I advocate the use of an iSisXL spectrophotometer to reduce the time and effort to read the test patch pages. Otherwise, an ES‐1000 or ES‐2000 can be used within a Fiery RIP, or an XRite spectrophotometer for external software, but of course, using a hand-held device takes more time.

In some cases, the profiles being used in Photoshop may not be the same as the profiles on the RIP controller. One example of this is if the USWebCoatedSWOP profile is being used in Fiery Creative Suite with a newer RIP controller that has the SWOP2006_Coated3 profile installed from the factory. In these cases, you may import the profile you are using for the working space definition in Creative Suite onto the RIP's controller so it is available in Color Setup.

Another example is if you are using a custom press profile for a conventional press and need to match the RIPs color output to that press.

If your inkjet is driven by RIP software then part of the calibration and profiling process is setting the printer options, ink limiting and linearization and it is with these that the root of most problems can be found. Getting the printer options right for any media can take a while, factors such as the number of passes, resolution, head height and drying times all can have a big influence on the print. Again the media manufacturer should be able to guide you.

Specific settings that may help:

Optimized: Creates custom calibration d‐max calibration targets as read from the profile test patch page(s). 
This setting should generally be left ON, which is the default for most printer/copiers. Only the d‐max endpoint is read from the target. The intermediate curve is calculated using a general formula and does not follow any unique density variations in the printer/copier.

Black Generation: Specifies toner limit and GCR parameters. 
Specifying a black toner maximum of 95% instead of the default 100% will provide a smoother tone and gloss generation in the deep shadows. If designated at 95%, TAC reaches a 180‐260% value in the shadows, while designating at 100% usually causes a TAC drop to about 130%. Using the 95% black specification prevents a gloss roll‐off in the shadows on some media, while using the 100% black specification may reduce total toner usage. 

95% is usually recommended for best image quality. A TAC (Toner Limit) value of 260% should be used. Default values for Ricoh printer/copiers in CPS Ver 3 and Ver 4 may default to either 400% or 270% dependent upon the revision. 

Very aggressive GCR settings may reduce banding and total toner usage dependent upon the colors found in the source job. Changes to other parameters may be used for specialized purposes.

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Do you have a color management question, horror story or event to share?

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Don "Hutch" Hutcheson Interview

With more than 41 years of experience in photography, design, prepress, printing, and color science, Don Hutcheson has pioneered many techniques we now take for granted, like RGB workflows, soft proofing, extended-gamut printing, and digital proofing.
In 1995 he started the world’s first color management consultancy, HutchColor, LLC, to bring the concept of ICC color management to professional graphic users. Today he continues to train the world’s top printers, publishers, agencies, photographers, and designers through private consulting and public conferences.
In 2006 as chair of the IDEAlliance GRACoL Committee, Hutcheson used his own proof-to-press calibration method (now known as “G7®”) to produce the current GRACoL and SWOP data sets. Since then G7 has made standardized printing and proofing easier and more accessible to thousands of printers and print buyers world-wide.

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CR:     Let’s start with a bit of history. How did you first come to be interested in digital color, and what kind of training prepared you for the career you now have?

DH:     Digital color is the child of desktop publishing, which evolved from electronic color scanning, which in turn evolved from graphic arts photography or “color separation” – one of the key enabling technologies in the development of color printing. Like all printing, digital color is therefore simply a form of photography, which has been my passion since I was 13, so its natural that I should be interested in it.

From 18 thru 22, I served a five-year apprenticeship as a graphic arts camera operator at a company called Photo Engravers, Ltd. In Auckland, New Zealand. When they bought one of NZ’s first electronic drum scanners – a Hell C-296, the union wanted it to fail and put me on it with nothing but a badly-translated German manual.

I twiddled every knob and made every mistake you can imagine, including one day removing all the unwanted inks and replacing them with black. When that job hit our 1-color proofing press a few days later, it was like nothing anyone had ever seen before and I was nearly skinned alive, until they added the black plate, when suddenly everything looked wonderful. Today we call that GCR.

Though designed for CMYK work, I saw the scanner’s photographic potential and found I could make just three RGB negatives and print them onto photo paper through RGB filters. With a little experimentation I was able to make prints that matched not only the color of an original transparency, but also the subtle highlight and shadow details with a level of perfection hitherto unobtainable by analog means.

Although the C-296 was not a digital scanner, it was my first experience of what we now call digital imaging and I’ve been hooked ever since.

CR:     Your career has spanned several decades – what are some of the technologies that have come and gone during that time?

DH:     Continuous-tone camera separations, direct-screening camera separations, tray development, nitrogen burst development, glass screens, contact screens, silver masking, tri-pack masking, double-overlay masking, wet etching (with potassium cyanide!), dry etching, film stripping, ruby masking, analog proofing (AgfaProof, DuPont Cromalin, DuPont WaterProof, 3M Color Key, Transfer Key, and MatchPrint, Remak, etc.), drum scanning – you name it.

CR:     Is there any technology or ideology that has faded from use that you might hope we re-discover? Or what might be the next bleeding edge tech in the world of color management?

DH:     I’ve always loved the early continuous-tone printing methods like Collotype, partly because there are no dots to interfere with fine image detail, but also for their purity of color. Halftone printing imposes some color space limitations that don’t exist in true continuous-tone printing, where ink film thickness is varied rather than dot size. If someone invents a practical way to print truly continuous-tone CMYK with offset or digital efficiency, it will have a dramatic impact on fine-art reproductions and expanded-gamut applications.

As for the bleeding edge of color management, today’s biggest challenge is the huge difference between the official D-50 illumination standard and the actual light sources in viewing and measuring equipment. Color management is based on the assumption that we can measure color as it is seen by the human eye, but we are far from achieving that to a high level of accuracy.

The problem lies in the D-50 standard itself, which defines the quality of “standard white light” as a graph of emitted energy vs. spectral wavelength. Unfortunately, the D-50 spectrum is based on hypothetical “daylight”, rather than any commercially-available light source, so D-50 can only be crudely approximated by today’s viewing and measuring equipment. This means certain inks, dyes, papers, etc. can measure quite differently than they appear in a so-called D-50 viewing booth, and often an excellent “measured match” (with effectively zero delta E) can look unacceptable visually, and vice-versa. This disconnect between the D-50 standard and real-world light sources becomes even more of a problem as the demand grows for ever-higher standards of measurable color accuracy.

The obvious solution is to replace the D-50 standard with the spectral curves of a commercially-available light source, such as the fluorescent tubes used in today’s viewing booths, or some new LED equivalent, but agreeing on a new light source is fraught with political, economic and patent issues. Meanwhile, there are work-arounds that can reduce or eliminate the problem, but because they deviate from the D-50 standard, they are difficult to implement en masse. The new M1 measuring standard solves part of the problem but is far from a complete solution, and has in many cases exacerbated, rather than reduced, the related problem of OBA-enhanced papers, which fluoresce under UV light.

CR:     Let us now discuss the G7 protocols and their evolution – can you walk us through some of the early days of G7?

DH:     Around 1980 I developed a simple way to calibrate a color scanner to match the tonality of one printing or proofing system on another. At the time, “Dot Gain” (now called “TVI”) was the accepted basis for press calibration, but I found that consistent dot gain failed to give consistent visual appearance with different press conditions or technologies, like offset and pre-press proofing.

To solve the problem, I developed a simple neutral density-based technique that achieved a perfect visual match on neutral grays, regardless of inks or technology. But if the dynamic ranges of two devices didn’t match, I had to tweak the graphs to meet at the shadow point, while keeping highlight regions identical. That “shadow compression-expansion” principle remains one of the key features of G7, and the technique I used back in 1980 is still alive today in the free G7 Graph Paper Method.

Fast-forward to the 1990s when CtP removed film from the plate making process and the question became “what do we calibrate?” Previously we linearized the scanner or film setter, but now you couldn’t do that. So I put my 1980’s method into an Excel spreadsheet that allowed any press to match the tonality and gray balance of any printing or proofing system, and called the process “P2P” for proof-to-press or press-to-proof.

In 2004 the GRACoL committee used the P2P process to help develop the new GRACoL 2006 color space. We followed all the ISO 12647-2 rules except the obsolete TVI curves, which we replaced with NPDC (Neutral Print Density Curves) averaged from a number of ISO-standard press runs made with un-calibrated plates. The same shadow-weighted algorithm from 1980 was used to adjust the NPDC curves in shadow areas to fit any printer’s dynamic range, while preserving crucial highlight tonality.

To standardize gray balance, we followed the logic of the ICC’s relative colorimetric rendering intent, defining CMY gray balance as a function of paper color, reduced in proportion to dot percentage. This also mimics the human visual system’s “chromatic adaptation” phenomenon, and a camera’s auto white balance function.

GRACoL2006 and its sister SWOP2006 color spaces were wildly successful but to our surprise, many people were more interested in the P2P calibration method, so I donated it to Idealliance who re-named it “G7”, and the rest is history.

CR:     You encountered a lot of resistance initially. Can you give us some insight as to what that was like?

DH:     A fundamental rule of science is that any new discovery should be challenged rigorously. And a fundamental law of human nature is to resist change for change’s sake. So it’s not surprising that some industry experts and associations with a vested interest in the old TVI calibration method did their best to kill G7.

The main opponents to G7 were FOGRA, ECI and BVDM – three German associations roughly equivalent to Idealliance, that do great work in promoting standardized printing in Europe.

In 2005 I offered the P2P system freely to FOGRA and ECI, and suggested they partner with Idealliance in its development. But the request went unanswered until January 2006, when they announced their PSO certification system, which had been developed in secret while G7 was an open, public project.

PSO is based rigidly on the ISO 12647-2 standard, with emphasis on TVI curves, while G7 exposes the weaknesses of TVI and provides a more effective alternative. G7 was obviously seen as a threat to the revenue potential of PSO, but the PSO program could easily have replaced TVI with G7, or offered the option of TVI or G7. Instead those organizations refused to acknowledge G7’s many benefits, and took instead an aggressive public stance against G7, Idealliance and myself personally.

The good news is that ten years later, G7 has been far more successful than PSO, largely because it works more effectively, is far less expensive and can be used on any printing system, not just offset. There are now hundreds of G7 Master sites and thousands more unregistered users world-wide. In fact many German and European printers and print buyers have secretly adopted G7 – they just don’t advertise it.

CR:     When did you know that G7 was going to become the de facto standard?

DH:     As soon as we released GRACoL2006, it became obvious that much of its appeal was in the G7 calibration process. In 2006, Idealliance provided the G7 How-To and GRACoL and SWOP profiles freely, with thousands of downloads in the first few weeks. Printers all over the world began praising G7 as the first really useful calibration system they’d ever tried, even if they weren’t printing to GRACoL. Other processes like Flexo, screen, xerography, gravure, etc. also adopted G7 because it made life easier – especially when they had to come as close as possible to a GRACoL proof without the benefit of ICC color management.

CR:     What are some misconceptions some folks might have about adjusting color through grays?

DH:     The most common misunderstanding about G7 is that it’s a replacement for ICC color management, which is not true. G7 uses just four one-dimensional curves to achieve good gray balance and tonality, much as a photograph’s exposure and color balance problems can be “corrected” in Photoshop with RGB curves alone. When grays are corrected, colors are moved in the right direction, but may fall short of complete accuracy depending on additional factors that cannot be corrected with simple 1-D curves, like ink hue, trapping and opacity.

By contrast, ICC color management uses more complex n-dimensional Look-Up Tables (LUTs) to apply hue, saturation and lightness changes discretely to different colors. G7 generally does a better job on neutral grays, however, and provides several additional benefits, so the best of both worlds is to use a combination of G7 plus ICC.

CR:     Is there any color device that cannot be brought to G7 standard?

DH:     No, but systems that don’t have user-programmable 1-D LUTs may not be compatible with the G7 calibration method. In those cases, ICC profiles can simulate a G7-based color space like GRACoL, with the same visual effect, but without the special benefits of separate G7 calibration.

CR:     Are there any particular books, white papers, YouTube channels or other reference sources you might recommend to color management beginners?

DH:     One of the earliest but still one of the best books on color management is Real-WorldColor Management by Fraser, Murphy and Bunting. For color geeks, I recommend Measuring Color by R. W. Hunt. The annual PIA Color conference (www.cmc.printing.org) is another excellent color management learning resource.

CR:     What are you working on now? How’s it going?

DH:     As a photographer, one of my life-long passions has been “expanded gamut” printing, i.e. getting more color out of conventional printing to make it look more like photography. My most recent efforts in that regard contributed to the new Idealliance XCMYK color space and methodology, which is based on maximizing the color gamut of four-color offset and can be simulated on any digital color system with sufficient gamut. In 2017 Idealliance will extend that work to consolidate and standardize both 4-color and 7-color expanded gamut strategies, ink sets and workflows.

CR:     I know you are a great lover of IPA’s. Got a favorite, and why?

DH:     America is blessed with the greatest selection of micro-breweries in the world. The beer I drink most often is Dale’s Pale Ale, whose red, white and blue can prevents oxidation by light. Dale’s has an excellent balance of hops without the excessive alcohol levels that spoil so many IPAs. Other good brews include Sierra Nevada, Anchor Steam, Lagunitas, Stone, and many others.

Many, many thanks to Don for taking time out of his busy schedule to speak with us.

To see and hear Don speak about the G7 protocols, as they apply to wide format printing, click HERE.

Check our Definitions page for many of the terms used above.

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Do you have a color management question, horror story or event to share?

Email me at reilley4color@gmail.com

Closed Loop Color

CLOSED LOOP COLOR

Before digital color management became the rigorous science that we currently use, print professional all had a bag of tricks to get their desired color results from a given printer. They had experimented, suffered, worked around and generally gotten to know their print device, warts and all, in order to get what they wanted from. Things got considerably more complicated when another device, like a scanner, or wide format printer was part of the mix.

Then when they got a new device, they had to start over from scratch.

This was Closed Loop color management, a tight bond between user and device.

Open Loop color management, however uses the "Universal Translator" concept, going from the input color start point color space (usually RGB of some kind) to L*a*b* color space - which is based on human vision, and a larger color space than any digital device - then from L*a*b* to CMYK+, according to the device profile of the printer. This allows users to plug new equipment into the mix without having to change color management setting for any other device. Essentially, it takes the input of any color space, then translates that to the output gamut of the print device.

As a method of color management, closed loop color is usually considered a mistake. However, some higher end production printers use Close Loop Color Control (CLC) to ensure color fidelity throughout a print run. The two concepts are very different.

Closed loop color is essentially an on-press feedback system that scans and measures the color bar on the moving paper (web or sheetfed) -- while the press is in operation -- and then feeds this information back to the press console to make automatic adjustments. When the color information recorded across the sheet: the ink density (or ink film thickness, and amount of light reflected off the press sheet) and the spectrophotometric data (or measurement of the hue of the ink) deviate from the specified levels, the closed loop system automatically adjusts the press to bring the color back to its target.

Why is this important? More and more presses include such measuring devices to ensure that the color you specify within your design application (InDesign, Quark, Photoshop) can be carried consistently from your computer to the printer's proofing devices and then on to the pressroom. This is also called color management.

So, remember the difference - the closed loop color management system is archaic and inadequate to modern CM needs, while closed loop control control is a breakthrough of technology that allows a digital press to maintain color throughout a lengthy print run.

n addition to color fidelity, additional benefits of closed loop color include reduced make-ready times, reduced paper waste and ink consumption, and the ability to save ink-presets for later use (i.e., to record all color information in the press console for later replication in future jobs).

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Do you have a color management question, horror story or event to share?

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Brightness vs Whiteness

For most printers and print buyers, the terms brightness and whiteness are interchangeable. However, when describing the characteristics of paper there are some important differences between the two terms.

• Brightness: Defined roughly as the amount of blue-white reflectance compared with magnesium oxide, which is considered 100% bright. 
• Whiteness: The extent to which paper diffusely reflects light of all wavelengths throughout the visible spectrum. The assigned ideal white standard totally reflects all light throughout the spectrum.

Brightness refers to the percent reflectance of blue light, as measured at a wavelength at, or about, 457nm. The choice of that wavelength is based on the sensitivity of the human eye to blue and yellow light. That wavelength represents "blue-white," which the human eye perceives as whiter than white. Brightness was originally a test in paper manufacturing to measure the effectiveness of the bleaching process in removing yellowness from pulp.  In lay terms, brightness is a measurement, on a scale of zero to 100, of the amount of light reflected from the surface of a paper.

When paper is bleached, the spectral reflectance curve increases the most in the blue and violet range, at about the 457nm point. This has also made the measurement of brightness well suited for measuring the aging of paper because paper yellows with age. Most white papers are in the 60 to 90% brightness range.

Paper brightness requirements for ISO 12647-2. Currently there are no specifications for ISO 12647-3 (newsprint), ISO 12647-4 (gravure), ISO 12647-5 (screen printing), or ISO 12647-6 (flexo).

The beginning brightness range for a base paper pulp is from 0-100, but during the papermaking process, optical brightening agents (OBAs) are frequently added to improve a paper’s brightness. The function of an OBA is to reflect ultraviolet (UV) light from the light source as visible light in the blue spectral region. On very bright sheets, this can create a situation where there is more reflected visible light from the surface of the paper than the light source emits, resulting in a measurement in excess of 100. 

See our last article - "Paper is the 5th Color" for a closer look at OBAs

Whiteness, on the other hand, refers to the extent to which paper reflects equally the light of all wavelengths throughout the visible spectrum. A truly white sheet of paper will not absorb one wavelength of light energy more than another. 

For example, if a sheet of paper is placed under a full spectrum light, most of that light will be reflected back equally and the paper will appear white. 

However, if some of the wavelengths of light energy are absorbed, the color of the paper will shift to the light which was not absorbed, but was instead reflected back to the viewer. That is why a red sheet of paper appears red in white light because it absorbs all the other colors and reflects only the red.



Most white papers will have a total reflectance between 50% and 90% with variations as high as 20 to
30% at different wavelengths.

In North America, brightness is the most commonly referenced term used outside the industry itself.

However, in Europe and other parts of the world, whiteness is the more common reference.

Unfortunately, there is no correlation between a paper’s brightness level and its whiteness level. They are based on different measurement systems.

Shade - the color of the paper - is the third factor that impacts one’s visual perception of paper. Shade is typically measured using the universally accepted CIE LAB model.

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Do you have a color management question, horror story or event to share?
Email me at reilley4color@gmail.com

Paper is the 5th Color

Paper is an analog variable in the world of digital printing. It directly affects the hue in the highlights,  it affects the entire color gamut size for the print job, has a powerful impact on shadows, and is often outside the control of the production workflow.

While many people believe that traditional color management is about managing the CMYK inks and their separations, paper has as much of an influence on the color of the final printed piece as it does on the mechanical and chemical action of the inks or toners. Although a given paper brand’s attributes may be consistent, paper characteristics are not standardized. There is variation in attributes between mills as well as variation around an attribute property from a given mill. Paper is considered a commodity but its properties are a long way from standardized.

A lot has changed in the world of paper. One of the biggest changes in recent years has been the increased use of optical brightening agents (OBAs) in many papers to give the appearance of a very bright white paper. Printers have been known to accuse paper companies of using cheaper goods and “cheating” by using optical brighteners.

The initial choices made on paper selection might not take into consideration the impact later in the production chain, and sometimes those decisions can have unintended consequences.

White papers are not RGB 255,255,255. Paper companies control the shade of their papers by adding dyes and other chemicals to affect appearance. More dyes, less reflection, more color compensation. The paper owns some of the color space so detail that requires paper’s hue cannot be reproduced. The recent trends toward blue white papers have resulted in more and more dyes in the paper and further deviations from neutral. Some of today’s papers are equivalent to a 3 percent cyan screen.

Modern color management solutions do allow you to bias your results to either a strictly neutral result with no consideration of paper color, or to neutrality based on the paper color.

This can be very important, as the human eye will quickly key in on the “white” of the paper and judge other colors on the paper based on that shade.

Paper shade, or white point, is the key attribute of paper and is measured using L*a*b* based on CIE XYZ. Described by these three values, color management applications calculate complex color inter- pretations to characterize paper and predict paper’s effect on color reproduction.

OBAs are used to increase the apparent brightness and whiteness of papers and their use is becoming more prevalent in paper manufacturing. They increase brightness and whiteness by absorbing energy in the ultra violet and emitting (fluoresce) the energy in the blue area of the visible spectrum. Because, to the eye, blue/white looks "whiter" than yellow/white OBAs are not really whiteners, but bluing agents. OBAs are also used in ink to expand gamut or brighten 4/C image printed on poor substrates - e.g. newsprint.


While it is not practical for printers to quantitively measure the OBA content of the materials that they use, it is quite an easy matter to qualitatively see the OBA content. All it takes is an inexpensive (less than $15 USD) "black light."

For example, with the black light it is easy to see that the paper used for the Pantone Goe system swatch book (on the left in the image below) contains more OBAs than the conventional Pantone spot color swatchbook on the right. Also, it's clear that the uncoated paper section in the Pantone spot color swatchbook contains more OBAs than the coated section.

Viewed in light that has an ultraviolet component, the papers appear bright and blue. They have an apparent expanded gamut. However, the printed hues will mutate, or change color depending on the light source. This effect is called metamerism and drives a need for light booths and an understanding of the viewing conditions when color matching or judging color. Simply put, printed hues shift, particularly in the highlight tones, when papers contain optical brighteners.

In reality, the rise in the use of brighteners can be attributed to a host of reasons, including production efficiency for maintaining a consistent look to a paper with changing content and a desire from customers for a brighter sheet at lower cost.

Another, more subtle problem can be the intended colorcast of the sheet. While in some ways we might consider OBAs an unintended colorcast, designers will sometimes purposefully choose a paper that has a colorcast.

The inks that are typically used in four color process printing block, to varying degrees, the fluorescence in papers containing OBAs. Black and magenta block the greatest amount, yellow a lesser amount, and cyan ink least of all. What this means is that when an image is printed using a halftone screen, lighter/pastel tones allow more more of the brightening and color shift of OBAs (towards blue) than the shadows. Color is effectively skewed towards the blue from shadows to highlights – but only when the paper being printed on has a high OBA content.

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Maintaining proper viewing conditions for print evaluations is a key part of color management.

The standards for viewing booths have changed over the past couple of years with the most recent release of ISO 3664 Graphic technology and photography — Viewing conditions.

If paper contains optical brighteners, color matching must be done in reference light conditions. When proofing on job stock that contains optical brighteners, it is important to critically examine both separations and curve effectiveness in the cyan containing highlight areas. The cyan/yellow color balance is hardest to achieve with these papers.

Even proofing papers contain optical brighteners. Creating profiles on these papers requires interpretation and tweaking if the press papers have a different level of optical brighteners or if the press papers have no optical brighteners.

Finally, optically brightened papers lose their fluorescence over time especially if exposed to light. The paper yellows. Print hues shift. Once printed, there is no recovery of the original paper whiteness so this should be kept in mind when a job reprints. Trying to match a first printing several months after completion is almost impossible. New proofs are a minimum requirement.

What additional tools can color management bring to the table to help tame the paper problem?

Traditionally, the way to “solve” OBA problems was to ignore them, primarily by using a filter that cut the UV light to stop it from hitting the paper and thus prevented the brightening effect of the OBAs. This is still a very effective approach to process control, but it is no longer the norm in color management. The other way we ignored it was by doing just that, not acknowledging the problem.

Today, we are much more likely to solve the OBA problem by quantifying the amount of OBA by including the UV in the measurement and then adjusting the ICC profile to compensate for its presence. Some recent color solutions provide Optical Brightener Correction (OBC) technology, which allows you to fine tune the profile results by evaluating specific test charts against a series of Munsell color standards in the target viewing condition. This combination of physical standards and measured results allows for a uniquely precise correction for optical brighteners.

An additional parameter that can be handled in color management is the final viewing environment. Traditionally, a graphic arts workflow targets a daylight illuminant (usually noted as D50/2 – describing the illumination and viewing angle). One additional way to fine-tune the result is to define the viewing condition of the final destination or illumination at the intended point of use if it is not D50.

This can be done by either using CIE defined illuminants or by actually measuring the lighting in the final environment.

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And what about Glossy Paper?

Paper gloss is related to surface roughness and therefore affects color reproduction. Light of all wavelengths is reflected from the surface of paper. How it is reflected defines both its gloss and dot gain characteristics.  

If the paper is glossy and smooth, it scatters less light and there is less dot gain. Light is reflected almost like a mirror (specular reflection). 

Matte, dull and uncoated papers scatter more light resulting in more dot gain. Also, these papers require more ink to achieve a given density further increasing the dot gain. 

Papers from different manufacturers absorb ink and toner/developer solution differently. There is no overall standard for surface roughness, ink absorptivity or developer absorptivity within the paper classification scheme. For the most accurate color, press profiles should be made on the chosen stock for a particular job. 

Matte and uncoated papers are even more variable.

The best color reproduction will occur on:

• Bright papers with uniform spectral reflection;
• Papers that are smooth and glossy;
• Papers that are neutral in shade; and
• Papers that exhibit minimal fluorescence.

One curve for all paper surfaces leads to less than optimum color.

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Do you have a color management question, horror story or event to share?

Email me at reilley4color@gmail.com

Device Link Profiles

Color profiling software also can generate device link profiles.

A device link is a type of International Color Consortium profile that contains two profiles inside of one. In order to create a device link profile, you select the two profiles, along with settings, and then save these ‘linked’ profiles as a device link profile. A device Link profile always contains a source color space and a destination color space, and the conversions always move from the source color space to the destination color space, saving time in file preparation and processing. They are most useful to people who repeatedly use the same specific configuration.

Why might device link profiles be required?

One example is when a scanner application does not embed the source profile in the document containing the image it creates. Storing the scanner’s profile eliminates the need to request the appropriate source profile each time the user wants to print with a configuration involving that scanner.

Perhaps a user also may want to see how a scanned image looks when printed using a specific printer, or may want to look at many images captured on the same scanner at different times before printing the final image.

Since the same devices are involved each time, the graphics application displays a list of device link profiles that the user had previously created for various configurations, allowing the user to select the appropriate device link profile for the current activity.

Another reason to use device link profiles has to do with maintaining channels in color conversions. Typical ICC color conversions require all of the colors in the file being converted — including the black channel. device link color conversions allow the user to maintain the K channel so that the color conversion can happen without any changes to the K channel — such as converting K type to CMYK type. This can be important when making color conversions for certain types of inkjet proofing where you need to maintain the black channel.

It is even more important for making color conversions during plate generation. When used during ripping or plate generation, the black channel must be maintained and device links are a must. In this scenario the device link is used to make the press simulate another printing condition, or to match a printing condition such as GRACoL. Not every platesetter RIP can use device link profiles, but many can, and for those with RIPs that can’t, there are third party applications that can provide these conversions.

Device links are a required component in conversions between different printing conditions, e.g. from offset to gravure. Black channel conversion is achieved with exacting results. Whether single black or rich black output is specified, the device link will manage the requirement.

Currently device link profiles can’t be embedded or assigned in applications like Photoshop because they contain mathematical information for a color conversion rather than describing a color space. Because of this, device link profiles are more complicated and less flexible than traditional ICC profiles and are classified by the ICC as a special type of profile.

A few other points about device links:

• only one rendering intent is available, that which was selected at the time the link was created. 
• links cannot be embedded into images 
• the rendering intent encapsulated in the link is selected in the 'default intent' field in the profile's header. 
• a profile sequence tag in link profiles documents the profiles used to create the profile. 

If you are looking to create your own device link profiles, I personally like the iPublishPro 2 software from XRite.

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Do you have a color management question, horror story or event to share?
Email me at reilley4color@gmail.com

The Role of the RIP in Digital Color

Raster image processors (RIPs) control printing devices.

They translate, in a very direct way, the page description language of PostScript into a bitmap image, either CMYK or grayscale, including trapping, font data, formatting, kerning, color input/output profiles, bleed, imposition, metadata and legal validation. What you send to the printer gets translated into a picture the printer is capable of reproducing, and there you go.

They have become increasingly sophisticated and play a significant role in the Color management because they process files for printing on digital and offset output devices, including proofing and CTP systems as well as digital printing devices.

While you can get adequate results from a simple printer driver, which performs many of the same functions as the RIP, dedicated RIP software can offer a great deal more control, more finely grained tuning of files for fine art or production applications. RIPs can offer print queuing, batch processing, color separations, halftone screening, as well as checking for missing fonts or graphics.

An effective RIP incorporates such things as ICC-compliant color management system and profiles as well as workflow integration to deliver optimum results. It cannot operate as an isolated application with proprietary tools.

Rather, RIPs must integrate with a production environment and facilitate the exchange of color profiles among the various constituencies of the Color Management Workflow, including designers, agencies, prepress operators and print service providers.

Keep in mind that graphics creation packages allow users to create files that can be very difficult to print. Also, many designers have little in-depth knowledge about the printing process and are not aware that their designs create production issues. At a minimum, an effective RIP accommodates these complex constructs, so the final printed product closely matches the design intent.

It also widens the range of file types that can be accepted into the production process. In addition, an effective RIP should be able to handle special or spot colors and correctly process overprints and transparencies.

RIPs also concatenate variable data, pairing the context of a database expressed as a CSV (Comma Separated Value) text file with tags in a PDF file to replace the tags with variable data, whether words or pictures, based upon the values from the database.

Transparencies and variable data do not play well together, since Postscript is a layers page layout description language, and both of these items prefer to be the topmost layer in the stack, and when they have to fight it out, VDP usually wins over transparency. However, a properly tuned RIP can process these files correctly, ensuring the final PDF that goes to print is correct.

Each RIP handles color management the same way. Input color profiles are translated to L*A*B* values, which are then converted to the output color profile assigned to the RIP, and the resulting PDF file matches the output profile directly.

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Do you have a color management question, horror story or event to share?
Email me at reilley4color@gmail.com

Ink & Toner

INK AND TONER

How color actually appears when produced on an offset or digital press is affected by several factors, including the printing plate quality produced from the original file or master for offset printing, the press settings, the paper, or other substrate, ink or toner types that are used to produce the job; and even the environment or condition of the press and the press area, regardless whether digital or offset.

Let's take a closer look at Ink and Toner

Ink

The press operator has significant influence on the way colors are produced in print. Factors include increasing or decreasing the amount of ink that is applied to the page for offset, and shifting the CMYK balance — that is, increasing the amount of one or more of the primary colors independent of each other — for either offset or digital devices.

By taking these actions, the press operator can match the proof -- fine tuning the press during print production to produce a printed sheet equivalent to the contract proof that the customer has approved or will approve. Offset and Web Operators can match printed sheets to proofs with a visual examination or by using color measurement tools.

It is important to understand that color matching between proofs and printed sheets may not always be 100% accurate, even if all of these steps are employed. Using measurement tools gives greater consistency than visual inspection, no matter how skilled the operator.

Did you know that 7-10% of all males  and 0.5-1% of all females have a color deficiency, which is why using instruments to measure color is more accurate than "eyeballing" color.

Here is free color vision test online you can use to showcase the point.

This situation is due to the fact that, especially in the offset environment, the proofing device uses different inks and may be printing on different paper than is actually used in final production at the offset press.

For example, more intense colors can be produced on a high-quality coated paper than on a less expensive, uncoated paper.

If a proof is produced on coated stock with the final product produced on uncoated stock, it may be difficult to obtain an accurate color match at press time. The more accurately the final printing conditions are met in the proof, the greater chance for success the entire print enjoys.

The density with which the ink is applied to the paper can be measured with a densitometer, which allows the press operator to deliver consistency, from sheet to sheet, and even job to job, especially if a job is being reprinted. A spectrophotometer is used to measure color accuracy.

While there are consistent standards that apply to offset inks, there are inconsistent standards relative to inkjet inks that are provided by different suppliers. This will be discussed further in the future.

Toner

This extremely fine powder, which has a consistency akin to talcum powder, gains an electric charge when it comes in contact with the copier's rotating drum. The copier's laser beam then removes the charge from the previously charged areas of the drum, leaving certain areas free to be coated with toner. The drum rolls over a sheet of paper with certain areas coated in toner, creating an image. Various mixed ingredients compose toner powder, in turn making up miniscule particles generally ranging in size from five to 15 microns---a millionth of a meter---around.

Read more : http://www.ehow.com/list_6757488_ingredients-copier-toner_.html

This extremely fine powder, which has a consistency akin to talcum powder, gains an electric charge when it comes in contact with the copier's rotating drum. The copier's laser beam then removes the charge from the previously charged areas of the drum, leaving certain areas free to be coated with toner. The drum rolls over a sheet of paper with certain areas coated in toner, creating an image. Various mixed ingredients compose toner powder, in turn making up miniscule particles generally ranging in size from five to 15 microns - a millionth of a meter - in size.

This extremely fine powder, which has a consistency akin to talcum powder, gains an electric charge when it comes in contact with the copier's rotating drum. The copier's laser beam then removes the charge from the previously charged areas of the drum, leaving certain areas free to be coated with toner. The drum rolls over a sheet of paper with certain areas coated in toner, creating an image. Various mixed ingredients compose toner powder, in turn making up miniscule particles generally ranging in size from five to 15 microns---a millionth of a meter---around.

Read more : http://www.ehow.com/list_6757488_ingredients-copier-toner_.html

This extremely fine powder, which has a consistency akin to talcum powder, gains an electric charge when it comes in contact with the copier's rotating drum. The copier's laser beam then removes the charge from the previously charged areas of the drum, leaving certain areas free to be coated with toner. The drum rolls over a sheet of paper with certain areas coated in toner, creating an image. Various mixed ingredients compose toner powder, in turn making up miniscule particles generally ranging in size from five to 15 microns---a millionth of a meter---around.

Read more : http://www.ehow.com/list_6757488_ingredients-copier-toner_.html

This extremely fine powder, which has a consistency akin to talcum powder, gains an electric charge when it comes in contact with the copier's rotating drum. The copier's laser beam then removes the charge from the previously charged areas of the drum, leaving certain areas free to be coated with toner. The drum rolls over a sheet of paper with certain areas coated in toner, creating an image. Various mixed ingredients compose toner powder, in turn making up miniscule particles generally ranging in size from five to 15 microns---a millionth of a meter---around.

Read more : http://www.ehow.com/list_6757488_ingredients-copier-toner_.html

This extremely fine powder, which has a consistency akin to talcum powder, gains an electric charge when it comes in contact with the copier's rotating drum. The copier's laser beam then removes the charge from the previously charged areas of the drum, leaving certain areas free to be coated with toner. The drum rolls over a sheet of paper with certain areas coated in toner, creating an image. Various mixed ingredients compose toner powder, in turn making up miniscule particles generally ranging in size from five to 15 microns---a millionth of a meter---around.

Read more : http://www.ehow.com/list_6757488_ingredients-copier-toner_.html

This extremely fine powder, which has a consistency akin to talcum powder, gains an electric charge when it comes in contact with the copier's rotating drum. The copier's laser beam then removes the charge from the previously charged areas of the drum, leaving certain areas free to be coated with toner. The drum rolls over a sheet of paper with certain areas coated in toner, creating an image. Various mixed ingredients compose toner powder, in turn making up miniscule particles generally ranging in size from five to 15 microns---a millionth of a meter---around.

Read more : http://www.ehow.com/list_6757488_ingredients-copier-toner_.html

This extremely fine powder, which has a consistency akin to talcum powder, gains an electric charge when it comes in contact with the copier's rotating drum. The copier's laser beam then removes the charge from the previously charged areas of the drum, leaving certain areas free to be coated with toner. The drum rolls over a sheet of paper with certain areas coated in toner, creating an image. Various mixed ingredients compose toner powder, in turn making up miniscule particles generally ranging in size from five to 15 microns---a millionth of a meter---around.

Read more : http://www.ehow.com/list_6757488_ingredients-copier-toner_.html

This extremely fine powder, which has a consistency akin to talcum powder, gains an electric charge when it comes in contact with the copier's rotating drum. The copier's laser beam then removes the charge from the previously charged areas of the drum, leaving certain areas free to be coated with toner. The drum rolls over a sheet of paper with certain areas coated in toner, creating an image. Various mixed ingredients compose toner powder, in turn making up miniscule particles generally ranging in size from five to 15 microns---a millionth of a meter---around.

Read more : http://www.ehow.com/list_6757488_ingredients-copier-toner_.html

This extremely fine powder, which has a consistency akin to talcum powder, gains an electric charge when it comes in contact with the copier's rotating drum. The copier's laser beam then removes the charge from the previously charged areas of the drum, leaving certain areas free to be coated with toner. The drum rolls over a sheet of paper with certain areas coated in toner, creating an image. Various mixed ingredients compose toner powder, in turn making up miniscule particles generally ranging in size from five to 15 microns---a millionth of a meter---around.

Read more : http://www.ehow.com/list_6757488_ingredients-copier-toner_.html

This extremely fine powder, which has a consistency akin to talcum powder, gains an electric charge when it comes in contact with the copier's rotating drum. The copier's laser beam then removes the charge from the previously charged areas of the drum, leaving certain areas free to be coated with toner. The drum rolls over a sheet of paper with certain areas coated in toner, creating an image. Various mixed ingredients compose toner powder, in turn making up miniscule particles generally ranging in size from five to 15 microns---a millionth of a meter---around.

Read more : http://www.ehow.com/list_6757488_ingredients-copier-toner_.html

This extremely fine powder, which has a consistency akin to talcum powder, gains an electric charge when it comes in contact with the copier's rotating drum. The copier's laser beam then removes the charge from the previously charged areas of the drum, leaving certain areas free to be coated with toner. The drum rolls over a sheet of paper with certain areas coated in toner, creating an image. Various mixed ingredients compose toner powder, in turn making up miniscule particles generally ranging in size from five to 15 microns---a millionth of a meter---around.

Read more : http://www.ehow.com/list_6757488_ingredients-copier-toner_.html

This extremely fine powder, which has a consistency akin to talcum powder, gains an electric charge when it comes in contact with the copier's rotating drum. The copier's laser beam then removes the charge from the previously charged areas of the drum, leaving certain areas free to be coated with toner. The drum rolls over a sheet of paper with certain areas coated in toner, creating an image. Various mixed ingredients compose toner powder, in turn making up miniscule particles generally ranging in size from five to 15 microns---a millionth of a meter---around.

Read more : http://www.ehow.com/list_6757488_ingredients-copier-toner_.html

This extremely fine powder, which has a consistency akin to talcum powder, gains an electric charge when it comes in contact with the copier's rotating drum. The copier's laser beam then removes the charge from the previously charged areas of the drum, leaving certain areas free to be coated with toner. The drum rolls over a sheet of paper with certain areas coated in toner, creating an image. Various mixed ingredients compose toner powder, in turn making up miniscule particles generally ranging in size from five to 15 microns---a millionth of a meter---around.

Read more : http://www.ehow.com/list_6757488_ingredients-copier-toner_.html

This extremely fine powder, which has a consistency akin to talcum powder, gains an electric charge when it comes in contact with the copier's rotating drum. The copier's laser beam then removes the charge from the previously charged areas of the drum, leaving certain areas free to be coated with toner. The drum rolls over a sheet of paper with certain areas coated in toner, creating an image. Various mixed ingredients compose toner powder, in turn making up miniscule particles generally ranging in size from five to 15 microns---a millionth of a meter---around.

Read more : http://www.ehow.com/list_6757488_ingredients-copier-toner_.html

This extremely fine powder, which has a consistency akin to talcum powder, gains an electric charge when it comes in contact with the copier's rotating drum. The copier's laser beam then removes the charge from the previously charged areas of the drum, leaving certain areas free to be coated with toner. The drum rolls over a sheet of paper with certain areas coated in toner, creating an image. Various mixed ingredients compose toner powder, in turn making up miniscule particles generally ranging in size from five to 15 microns---a millionth of a meter---around.

Read more : http://www.ehow.com/list_6757488_ingredients-copier-toner_.html

In its early form it was a mix of carbon powder and iron oxide. Then, to improve the quality of the printout, the carbon was melt-mixed with a polymer.

Toner particles are melted by the heat of the fuser, and are thus bonded to the paper.

In earlier machines, this low-cost carbon toner was poured by the user from a bottle into a reservoir in the machine. Current machines feed directly from a sealed laser toner cartridge.

Toner results also vary from manufacturer to manufacturer or from ink batch to ink batch.

Additionally, different paper types can result in different ink absorption rates, which in turn, cause color to vary from one paper type to another. The print drivers — or the instructions that bridge the document creation software and the print hardware, allowing the desktop user to print to the device — for inkjet printers generally have an option that can be selected to specify the paper type.

This option reduces that variability. Inkjet printers are relatively stable in their ability to deliver accurate color reproduction. This stability makes it easier to build a reliable color management process across the print workflow.

As you can see, it is critical to have coordination between the creator of the original file and the various stages of job processing throughout the print workflow to ensure that the output meets the customer’s expectations.

Unfused toner is easily cleaned from most water-washable clothing. Because toner is a wax or plastic powder with a low melting temperature, it must be kept cold while cleaning.

Recycling of pre-consumer waste toner is practiced by most manufacturers. Classifying toner to the desired size distribution produces off-size rejects, but these become valuable feedstocks for the compounding operation, and are recycled this way.

Post-consumer waste toner appears primarily in the cleaning operation of the photo-printing machine.

In early printers, as much as 20 to 25% of feed toner would wind up in the cleaner sump and be discarded as waste. Improved printer efficiencies have reduced this waste stream to lower levels, although on average 13% of the toner in each cartridge is still wasted.

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Do you have a color management question, horror story or event to share?
Email me at reilley4color@gmail.com