Archive for the ‘Color’ Category

what is “NPI” in inkjet

Posted: June 26, 2017 in Color

The Droplet – Print Resolution and DPI: A Brief Review
Print resolution is the capability of a printing system to reproduce image detail. There are two major factors that influence print resolution:
– The DPI (dots per inch) of a print system (which is characterized by a printhead or group of printheads).
– The level of sharpness and contrast, which is a component of the drop size. This is directly related to how an image is seen by the human eye.

No automatic alt text available.

Many factors contribute to the overall performance of a printhead: drop size(s), nozzles per inch (NPI), drop volume consistency, accuracy of drop placement, and print system integration. In addition, consideration of the viewing conditions, contrast, and viewing distance will help determine optimal print resolution for a print. If a higher print resolution cannot be seen by the naked eye, the benefit of that additional resolution is lost.
Inkjet printheads are distinguished by their nozzles per inch (NPI). Also known as native DPI, this is the rectangular grid of possible printable dots defined by the nozzle distance along the axis of the printhead, and by the speed and print frequency along the axis of the media motion. The NPI value of a printhead determines the location of dots, but does not actually determine the maximum possible print resolution, or size of the printed dot.
Printers also have the factor of effective DPI. This is the smallest incremental distance that a printer can shift from the middle of one point to the middle of the next. When resolution is increased on the axis of the media, this in turn increases the effective DPI, which also impacts the level of detail. DPI can also essentially be doubled by interleaving multiple printheads within the configuration.

source: CET Color


You say color is important, but do you know why it’s so important? In reality, color is a critical element in the manufacturing process. Unfortunately, many manufacturers are realizing that getting color right is much harder than it used to be, and the brands they support are asking them to meet tighter tolerances.

Here’s why.

While advances in color technology – think metallic packaging, pearlescent finishes, custom fabrics and vibrant new colors – entice customers, they also make it much more difficult to achieve consistency.

Take composite decking for example. You used to have two choices: gray or brown. And as long as you had harmony across the entire deck, customers were happy. But now with so many options – deep wood-grain patterns and exotic colors – manufacturers have to manage dozens of colors instead of two or three. Achieving consistency is much more difficult,

Packaging is another great example. Store shelves that used to be lined with printed boxes now include foil pouches, blister packs, and multi-substrate displays. Color is especially difficult to control with reflective and translucent surfaces, and what works for one doesn’t necessarily work for another.

Package designs come together on the shelf. Here you see pouches, labels, cartons, and corrugated with visual inconsistencies—these are issues that can be overcome.

From textiles to plastics to paint and coatings, the story is the same across every industry: color that used to pass muster is no longer good enough. And consumers and brand managers are getting pickier. If color doesn’t look right, consumers will right pass by the offending package or product for a competing brand, and the rejected products often end up as wasted inventory.

This is causing manufacturers a great deal of stress. Are you in that boat?

* Do you step outside in daylight to evaluate color?

* Are you emailing photos for others to evaluate and approve?

* Are you uncertain exactly which color you’re expected to produce?

* Is color that used to be “good enough” now being rejected?

If you answered YES to any of these questions, your visual evaluation program has room for improvement. Luckily it doesn’t require a lot of time, money, or effort to take the first step on the journey to consistent color.

Let’s take a look at the most common places color goes wrong in visual evaluation programs.

1 – The wrong lighting.

This image demonstrates why it’s important to evaluate color under standard lighting. See how the shade of red changes with the type of light?

As the temperature of light changes, so does our perception of color.

But what if you don’t know if the lighting in your lab or office is standard? Don’t cross your fingers and hope. PANTONE® LIGHTING INDICATOR Stickers are a much better option. Each sticker has two patches. If they match, you’re working under natural daylight conditions. If not, you should move to a different light source before making color decisions.

Of course, LIGHTING INDICATOR Stickers won’t show you how your colors will look under the fluorescent, incandescent or LED lighting found in stores, offices, and homes. The best way to know how your finished products will look once they enter the world is to use a light booth.

This is especially important if you’re producing parts that will be assembled into a final product, such as a cell phone case with a plastic back and rubber sides, or the side mirrors for a vehicle that must match the body at assembly. Just because they match your “golden sample” or physical reference under daylight doesn’t mean they’ll still look good in store, showroom or home lighting.

Light booths don’t have to be a huge investment, and the payoff in fewer rejections will come fast. To learn more about how they work, check out 10 Tips For Visually Evaluating Color.

2 – Less than perfect color vision.

Most people don’t even know they have some type of color deficiency, but it is incredibly common. In fact, about one in every 13 men and one in every 300 women exhibit some type of color deficiency.

This is the Ishihira Color Vision Test. If you don’t see a “6” in the left circle and a “2” in the right, you probably suffer from some type of color deficiency.

If you’re responsible for making color decisions, you really should take the physical test… which you can do as part of our Fundamentals of Color and Appearance seminar. If you’re just curious, the online color challenge is a fun, fast way to understand your color vision acuity.

3 – The wrong physical standards.

If you use physical standards, that’s great! They’re a precise way to communicate and evaluate color… as long as you follow a few basic guidelines.

This Quality Control Manager is comparing a textile sample against the color standard in the Judge QC to ensure it is visually correct under different light sources.

First, they need to be made from the right material. Let’s say you’re producing terrycloth fabric that will be used to make towels. Using a paper standard to evaluate the fabric color will not give you accurate results. Since material behaves differently with pigments, inks, or dyes, you need a standard that’s made from the same material to make good color decisions – a huge point of frustration for many manufacturers.

But, just like everything, physical standards are subject to dirt, smudges, and fading. Our Ultimate Guide to Caring for Physical Samples can help you keep yours in tip top condition.

4 – Inconsistent device color.

If you’ve ever walked into an electronics showroom and noticed the wall of new TVs showing completely different color, you already know inconsistent device color is a problem. Yet many of us don’t think about that when we’re using our handheld devices or computers to make color decisions. Did your camera capture the right color? Is the person you’re sending it to for approval seeing the right color?

Although sending photos electronically is not the best way to make color decisions, if sharing physical samples isn’t feasible it will help to color calibrate all of the devices involved.

Do you rely on visual evaluation?

Great color is an ongoing journey. Although new substrates and manufacturing processes may be adding chaos to your color control program now, color tools are also getting smarter. Take advantage of all there is to offer and get your color back on track!


In a perfect world, you should be able to put ink in the press, run a job, and achieve color consistency. Unfortunately, every year flexographic and gravure printing operations waste ink, substrate, and press time trying to get color right.

Although advancements in technology have made it easier to achieve color accuracy, the variables that affect color still exist. In this three part series we’ll share over two dozen reasons your color might be wrong at press side. Today’s topic looks at issues that can affect your color measurement instrument and substrates.

1 – Choosing the wrong instrument for the job

0°/45° spectrophotometers like our eXact and 500 series are very popular for print and packaging applications. But if you’re measuring reflective materials like poly or foil balloons or printing with metallic inks, you should be using a sphere geometry spectrophotometer.

Reflective surfaces pose a challenge because the effect of gloss can actually change the sample’s color appearance. A 0°/45° spectrophotometer excludes gloss to mimic the way a human observer views the sample. Therefore a measurement on foil with a 0°/45° can give a reading that does not match the way the eye will view it. Using a sphere instrument like a Ci64 can include or exclude gloss in different applications so it will match what the human eye will view. Check out our blog Effective Ways To Measure Reflective Surfaces to learn more.

2 – Using an out-of-calibration or malfunctioning spectro

A poorly calibrated instrument, especially one that has been dropped, can lead to bad color readings at press. If your instrument is not reading correctly and you’re not closely checking calibration, the ink techs could be toning colors that shouldn’t be just so the software says it’s correct.

This common issue is easy to fix with proper device maintenance. Calibrate regularly, at least before every operator change. If your instrument fails calibration or your measurements are really far off, it’s probably due for service. Our Caring for your Spectrophotometer blog explains our options for service and certification.

3 – Choosing the wrong illuminant settings

Make sure you read and evaluate your sample using the same illuminant and observer settings as your standard. Most printing facilities check colors under a D65/10° noon sunlight or a D50/2° horizon sunlight, but sometimes customers specify their unique tolerances ahead of time. Be sure you check this before you begin a job.

4 – Forgetting to switch the Delta E calculation

Delta E CMC had been the most popular choice since it was developed back in 1988, but Delta E 2000 has been gaining traction among some of the largest printer buyers. This updated tolerancing calculation is more forgiving when it comes to reading color samples. Check out our tolerancing blog to learn more.

Some workflows require you to switch between Delta E calculation for different customers. In the heat of a makeready, it’s easy to forget.

5 – Poor backing material

The backing material you place under your print sample is very important. Many samples are not completely opaque, allowing the instrument to pick up color data from the background and skewing your measurement results. Using a backer ensures the instrument is only reading the color data you want it to capture.

A stainless steel or wood table is not a good backing option. For consistent readings, always use the same black or white backer. You can purchase ISO certified backing materials, or pick up ceramic tiles from the hardware store… just make sure they’re from the same color lot. Also, remember to measure your standards with the exact same backing material you’ll be using press side.

6 – Manually entering L*a*b* values

Here’s something we see a lot. A customer sends a printer L*a*b* values to match, but doesn’t include the complete set of reflectance data that was recorded when the color was measured. Even if the printer manually correctly enters the L*a*b* values as the color standard, the final color might not be correct.

It’s best to read your standard into the software with a color measurement device, then export it as a .mif or .cxf file. These files can easily be e-mailed to and from customers to ensure everyone is working from the same color standard that includes reflectance data.

7 – Using the wrong filter (M0, M1, M2, M3)

To adjust for optical brighteners found in paper, more and more printers are setting their instruments to M1. The industry, including GRACOL, is starting to lean toward adopting this setting. If your operation hasn’t made the switch, it’s still important to understand that some standards might have been entered using one or the other. Be aware of these M settings in coordination with your operation, and, when you do make the switch, you may need to re-enter a lot of your standards.

8 – Different operating procedures

If only one operator follows these steps, your color isn’t going to be consistent. You need to document everything and communicate it to everyone involved in the workflow. Standard operating procedures (SOPs) provide a roadmap, help with issues, and make it much easier to train new employees. When SOPs are properly developed and implemented, they also ensure everyone is operating the spectrophotometer the same way, regardless of shift or location.


Ford interactive newspaper advert

Posted: February 1, 2017 in Color

Ford partnered with Israeli agency BBR Saatchi & Saatchi to create a 3-page newspaper advert. Each advert demonstrated different qualities of the features found in the new Ford Explorer SUV. Using a QR code, viewers could scan and place their phones on the highlighted area on the page. A virtual explorer SUV would appear on the reader’s mobile screen, demonstrating Park Assist, Adaptive cruise control, and power fold features.

Source: Ford interactive newspaper advert

Just when you’ve all cozied down with PDF 1.7 what happens?  Yes, that’s right.  A new standard rears its head.

Around the middle of 2017 the ISO committee will publish PDF 2.0 (ISO 32000-2). So by the end of 2017 you’ll probably need to be considering how to ensure that your workflow can handle PDF 2.0 files correctly.

As the primary UK expert to this committee I thought I’d give you a heads up now on what to expect.  And over the coming months via this blog and our newsletter I’ll endeavor to keep you posted on what to look out for as far as print is concerned.  Because, of course, there are many aspects to the standard that do not concern print at all.  For instance there are lots of changes in areas such as structure tagging for accessibility and digital signatures that might be important for business and consumer applications.

As you probably already know, in 2008 Adobe handed over ownership and development of the PDF standard to the International Standards Organization.  Since that time I’ve been working alongside other experts to ensure that standards have real-world applicability.

And here’s one example relating to color.

The printing condition for which a job was created can be encapsulated in professional print production jobs by specifying an “output intent” in the PDF file. The output intent structure was invented for the PDF/X standards, at first in support of pre-flight, and later to enable color management at the print site to match that used in proofing at the design stage.

But the PDF/X standards only allow a single output intent to be specified for all pages in a job.

PDF 2.0 allows separate output intents to be included for every page individually. The goal is to support jobs where different media are used for various pages, e.g. for the first sheet for each recipient of a transactional print job, or for the cover of a saddle-stitched book. The output intents in PDF 2.0 are an extension of those described in PDF/X, and the support for multiple output intents will probably be adopted back into PDF/X-6 and into the next PDF/VT standard.

But of course, like many improvements, this one does demand a little bit of care. A PDF 1.7 or existing PDF/X reader will ignore the new page level output intents and could therefore produce the wrong colors for a job that contains them.
In my next post I’ll be covering changes around live transparency in PDF 2.0.  Bet you can’t wait!
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The background
The last few years have been pretty stable for PDF; PDF 1.7 was published in 2006, and the first ISO PDF standard (ISO 32000-1), published in 2010, was very similar to PDF 1.7. In the same way, PDF/X 4 and PDF/X 5, the most recent PDF/X standards, were both published in 2010, six years ago.

In the middle of 2017 ISO 32000-2 will be published, defining PDF 2.0. Much of the new work in this version is related to tagging for content re-use and accessibility, but there are also several areas that affect print production. Among them are some changes to the rendering of PDF transparency, ways to include additional data about spot colors and about how color management should be applied.


iccMAX – new color management system

Posted: December 5, 2016 in Color


ICC color management meets the goal of creating, promoting and encouraging the standardization of an open, vendor-neutral, cross-platform color management system architecture and components. While the current architecture works well in many areas, new potential applications are emerging and it is believed that tomorrow’s color comunication will require a more flexible and extensible system. ICC has developed a new specification, iccMAX, that will address many of these new requirements.

It is important to note that iccMAX is not intended as a replacement for ICC v4, the existing architecture, but as an extension or alternative where requirements cannot be fully met by v4.

What is iccMAX?

iccMAX is a new color management system that goes beyond D50 colorimetry. This new specification has been approved by the ICC Steering Committee.

iccMAX profiles show v5 in the header to distinguish them from v4 and v2. iccMAX profiles also have class, sub-class, versioning and header information that differs from v4.

Users and developers are encouraged to make comments on the specification.

Backwards compatibility

iccMAX provides a significant enhancement to the functionality of the current v4 specification. It is recognised that in many industries, v4 (and even v2) meets existing color management needs and in these industries there will be no drive to move to adopt the new specification.

An iccMAX CMM will be completely backward-compatible and will recognise and correctly process v2 and v4 profiles. However, iccMAX profiles are not expected to be compatible with v4 CMMs. ICC has provided a reference implementation to help with iccMAX adoption (see below).

How will iccMAX profiles be different?

The main changes you can see are:

Profile Connection Space

The ICC v4 PCS has fixed D50 colorimetry, considered necessary until now to ensure interoperability and prevent ambiguity in colour transforms. iccMAX allows flexibility in the selection of illuminant and color matching functions. It supports spectral communication of colour information through an optional spectral PCS, and also supports the use of color appearance processing in the PCS, with the facility to store appearance attributes in a v5 profile.

Support for extended CMM functionality

A variety of new types of information can be stored in an iccMAX profile to support run-time transform creation of a smart or dynamic CMM. Examples include:

  • a new gamut boundary description (GBD)
  • support for spectral data
  • measurement data using the CxF format
  • a new encoding of Named colors to support tints

Programmable transforms (e.g. direct encoding of device models) are supported through Multi-processing Calc elements, with functional operators, conditional evaluation, persistent variables and vectorized operations for improved performance.

Future extendability is also provided through support for hierarchical data encoding, allowing optional data to be added later without requiring changes to the tag parser.

Abbreviated profiles

CMMs are able to select or define a suitable transform by referencing the color encoding standard (such as those listed in the ICC Three-component Registry) which can be specified in a v5 profile in place of a complete transform.


The iccMAX specification is now available to download on the Specifications page.

Spot Color Inclusion mechanism (SIM)

Posted: December 5, 2016 in Color

Spot Color Inclusion mechanism (SIM) for printing with 3 color process inks and spot color replacing black as fourth process color.

Wiki Defines Spot color as below

“In offset printing, a spot color is any color generated by an ink (pure or mixed) that is printed using a single run.” And it defines the CMYK color model (process color, four color) “as a subtractive color model, used in color printing, and is also used to describe the printing process itself. CMYK refers to the four inks used in some color printing: cyan, magenta, yellow, and key (black). Though it varies by print house, press operator, press manufacturer, and press run, ink is typically applied in the order of the abbreviation”.

Generally the cost and potential for problems for a print job increase as one adds more spot colors, due to the increased cost and complexity of added process inks and plates, and requiring more runs per finished print. However, because of the complicated process, spot colors are effective at preventing forgeries of money, passports, packaged products, bonds and other important documents. Money printing for example, uses secret formulae of spot colors, some of which can be seen by the naked eye and some that can only be seen by using special lights or applying certain chemicals.

In today’s competitive market, all the packaged products are printing spot color as part of their job work. Let’s see a below image as an example

Figure 1: Image courtesy :

In the above mentioned image, the image is with process CMYK colors and background is with pantone Reflex blue C.

For a typical printer in India who is having a 4 color printing press, these jobs will involve printing the job in two passes thus increasing the production cost by double. In the price competitive market, this erodes his margin as he has to fight to keep these kinds of packaging jobs in hold against a competitor who is having a 5 color printing press.

So there is an urgent need to support these printers with pre-press tools so that he can do the printing in one-pass. One option is to convert the spot colors in to process color combinations of C, M, Y, K percentages which will give the equivalent color perception.

For ex: a pantone blue can be printed with c=90% m=83% and black=10%.

But this method is prone to issues of color variations and color in-consistency.

So there is a need for some other tools to make the printing efficient and hence the tool of “Replacing a process color with Spot color without compromising print and color quality”. Hence the method of “SIM” is developed.


1. The process color and spot color combination in the printing job to be evaluated to understand which color can be replaced.

2. In the example shown above figure 1, the spot color used is Pantone Reflex blue. This leads to two possibilities of removing process colors and replacing it with process color. Either we can replace the Cyan with Pantone Blue or the black can be replaced with the pantone color.

3. A Hybrid test form (Chart 1) is printed to determine the best possible density for the spot color mentioned in the job. The density is determined on the basis of Hybrid Model Approach” (HMA)

4. The test chart is specially designed with a continuous wedge of solids along with dot gain patches. The sheet is printed with different densities from one end to other end. The variation is kept at 0.05 densities.

5. The wet densities were measured and sheets are allowed to dry. After 8 hours, the ‘Lab’ and ‘Print Contrast’ are measured on each density patches.

6. A curve depicting different lab and contrast values are generated. The lab values are compared with customer job specified standard lab values. It is observed that most of the cases, Delta E with medium deviation and maximum print contrast are matching.

7. Instead of choosing the lowest Delta E density, if we choose the point where both “print contrast” and “medium deviation Delta E”, the print results are better.

8. To evaluate this a ECI 2002 test chart is printed with the possibilities

a. Normal CMYK Printing

b. Pantone blue, M, Y, K process printing (replacing with Cyan)

c. C, M, Y and Pantone blue process printing (replacing with black)

9. Then these charts are measured with Heidelberg Color Tool box to understand the gamut of the above mentioned ECI 2002 test charts. It is observed that ECI test chart with option “C” closely suited the gamut required in the job.

10. A “Device-link” profile is created with the characterization data obtained from the ECI test chart.

11. A new dot gain curve is created to compensate the effect of Pantone blue over cyan and magenta regions. This dot gain curve is also obtained from the test chart.

12. Using image conversion software, the image is then converted to the destination profile with pantone blue elimination black color.

13. The job is then printed with C, M, Y, Pantone Reflex blue with compromising the use of pantone colors and print quality.

14. The printing quality is compared with 4 color + Process color printing and decided to make the analysis by human perception. The same sheets are given to “10 Standard Observers” and their visual assessments are compared.

15. Interesting the standard observers were not able to identify noticeable difference in print quality and they perceived it as usual CMYK + Spot color printing.

Further Scope:

The SIM system can be improved with an automatic mechanism to identify the image and recommend the right replaceable process color and corresponding “device link profile” and dot gain curve accordingly.

Chart 1