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E-Factor

Explanations on E-Factor by David Hunter:

I have been helping advance Color Management software for 20+ years, but it still has not been accepted in a universal way. Why? My opinion is because Color Management has not been able to close the loop between customers expectations and devices ability to print to those expectations. Introducing E-Factor™ one number to close the loop between customer “Expectations” (Expectation Factor), and an output devices ability to match those expectations.Our process allows users to quantify their expectations of a required color match in a number (called E-Factor) by taking our free on-line exercise (or hard copy exercise) to determine “how close is close enough” and help users understand if they are being reasonable. The second component allows printers to output targets, measure them in, upload to our site, and calculate what each devices E-Factor™ is in order to determine if it can meet the customer's expectations. If the output devices E-Factor is less than or equal to the customers E-Factor, then the printer can meet customers expectations, and customer will be happy.Every type of output device, and the management of that device contributes to its E-Factor that we can now quantify, EVEN BEFORE you purchase a new output device.Before you can color manage your devices, you need to understand how they reproduce color. We, as an industry, have done a really poor job of defining the precision and accuracy of a device BEFORE attempting to profile the output device. Ideally, you should know what level of precision (repeatability to itself) your printer is capable of and what level of accuracy (as an example to GRACoL or SWOP) your device is capable of, before you start selling/buying prints off that device. Our procedure defines an easy to follow procedure that will provide you with this information which is critical to effectively “color manage” your devices and meet customer expectations.


How close is close enough for You?

E-Factor is the expectation of the color match. It quantifies how close two colors or two pages have to be in order to be close enough to meet expectations. From a Technicians point of view, E-Factor relates to ∆E (00) for spot colors and 95th Percentile ∆E (00) for multi color and page comparisons (E in E-Factor has dual meaning, Expectation for the non color expert, and delta E for the color expert.

We can apply E-Factor to a person, a brand, a manufacturing shop and all the workflow components (output device, substrate variation, instrument variation, lighting variation) necessary for the successful color reproduction.

 

Our ChromaChecker Color Cloud Eco system is designed to allow you to pro-actively monitor your entire process, to ensure that your devices are performing to your desired level of color expectations.

Also, you can track your maintenance changes with your actual color results to know that the maintenance that you have completed is improving or not improving your results – your E-Factor results.

If the E-factor calculated by Print Inspector doesn’t match your expectations, then our ChromaChecker™ audits will take you through a process to determine where your problems are. Based on the problems, you can fix them which will produce a smaller E-Factor which provide a more accurate and precise print.

The genius of ChromaChecker™ is that it quantifies the expectation of the buyer, or the owner and co-relates it with an output device’s capability to match or exceed that expectation. Often times the output devices E-Factor is larger than the buyer, which means the buyer will not have expectations met. In this case, our on-line audits will lead an operator through the necessary steps to discover what the problem is, and help them fix it which will bring the E-Factor of the output device into the customer's expectations.

All variables in a color workflow can be defined with an E-Factor which calculates the precision and accuracy of all devices that are used for color reproduction including Instrumentation, Substrates/Paper, Output Devices, Lighting, Ink and unlike any other system available today, will alert the user if the precision of any of the devices is not suitable for the manufacturing workflow. ChromaChecker™ is also announcing Print Inspector. Print Inspector is a solution which defines an output device's E-Factor, and automatically associates the Instrument E-Factor and Substrate E-Factor at the same time to ensure the key variables related to an output device's printed result is due to the operation of the device versus the variables outside of the operators control including the substrate and instrumentation variable. The Print Inspector tracks both the precision and accuracy of an output device. Precision is defined through Variation Tool which calculates within page variation, within job variation, and between job variation. Accuracy is defined by calculating how close the output device is matching the Target Reference Space using 95th Percentile ∆E (00).

 E-Factor

is a single number which defines the quality of the color match and can be applied to all devices which influence color reproduction.In this way, unlike devices can be assessed t ensure they have suitable accuracy requirements based on the entire workflow (only has strong as weakest link- device with highest E-Factor is your easiest link). Depending upon the type of device, E-Factor is based on the most part on 95th Percentile ∆E (00) or for individual color comparison: ∆E (00). ∆E (00) does not scale across the hue range uniformly and does not compensate for factors like OBA and gloss so we created E-Factor. A smaller E-Factor reflects a closer color match. In the real world of printing, we do not expect a value of zero, which means a perfect match. E-Factor is a parameter developed to establish better communication in all possible fields in Graphic Industry. 



 Personal E-Factor

Personal E-Factor™ (Color Expectation Exercise) is a tool designed to quantify the level of color match desired by the user or group of users. To improve communication in the Graphic Industry we are offering an Exercise that translates an individual perception of "desired" color difference to a particular number – calculated using the 95th Percentile ∆E (00) formula. During the short exercise, the user is asked to compare pairs of corresponding pictures with given ∆E difference. We do not ask if the difference exists - which it does - but if the difference can be accepted. Take the on-line test here or learn more about the physical (hard copy) version by clicking here.
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 Corporate E-Factor

A corporation has a number of brands and ideally, should have the same tolerance for all brands. This Corporate E-Factor can be applied across all brand colors to ensure color is consistently meeting the Corporations E-Factor expectations.

 Lighting E-Factor

This parameter is used to describe Lighting Condition in areas where critical color comparisons are made: on press console or viewing booth for proof or prints evaluation.  E-Factor will define the difference between any two light sources or between any light source and a standard such as D50/2. A Sharing Function allows users to share Lighting Profiles with other users in order to co-relate viewing conditions in order to understand how prints will appear differently in different lighting. 

 

 Instrument E-Factor

This parameter defines Instrument (spectrophotometer) repeatability (precision). Measurements made using the ChromaChecker Instrument Inspector Target over time allows a user to monitor the instrument stability to its baseline (which is the instruments measurement average to itself). Ideally, the baseline is made when the instrument is new or just out of factory conformance. Instrument Inspector is a dedicated tool designed to monitor the quality of any instrument. It meets requirements for assessing ISO 9000 conformance in most countries to eliminate the need to send the instrument back to the manufacturer once a year.

 

 Inter-Instrument E-Factor

In the real world, different instruments measure the same set of patches differently. Unfortunately, there is no one instrument that can be used as the source of absolute data. Various instrument manufactures products differ in geometry, sources of radiation, monochromators, and sensors which results in different measurements for the same target set. Typically instrument vendors specify this parameter based on selection of 12 ceramic tiles which is not necessarily relevant to print on paper. 

Instrument Inspector offers a unique Compare tool that shows E-Factor (95th Percentile ∆E (00)) numbers between multiple instruments. Inter-Instrument E-Factor based on difference between instruments when multiple instrument’s baselines are compared. Share function is available for users in different facilities, or throughout the supply chain which allows sharing of instrument data to compare the E-Factor result due to different instruments and conditions.  Click here for a more in-depth technical paper on the influence that a physical target has when comparing multiple instruments.

 

 ICC Profile E-Factor

A number which shows the difference between data captured for profiling or characterization data set and optimized/ smoothed values delivered by an ICC-profile. This E-Factor helps the user understand how precise the profile represents the actual data that was measured to create the profile. Helps judge the precision of the profile itself, great tool to identify the quality of different profiling tools. 

 

 Substrate E-Factor

This number tracks how different the production substrate is from the specified substrate in the Substrate Inspector. Even paper from the same manufacturer can differ from one delivery to another, and sometimes, even within the same production batch. When configured properly, this E-Factor™ value is automatically tracked by Print Inspector and alerts the owner to variations of substrate affecting the variation of the print device. 

  

 Best Match Substrate E-Factor

Substrate Inspector has a best match function which can be used to find best match substrates to minimize the substrate E-Factor between different output devices, very useful for matching Proofing stock to House press stock, and for finding Digital stocks that match Conventional press stock.

  

 Printing Device's E-Factors:

It is important to understand that we are not measuring a device but specific device condition (device plus substrate plus screening/ink/post finish process). Consumables such as substrates, inks, toners, screening, and devices settings have a huge influence on the resulting color. Sometimes E-Factor can be improved by upgrading consumables, for example: replacing paper, inks with higher quality, more consistent products. But any such change requires building a new Print Conditions as a Track. Output devices produce various results when using different settings and consumables are used so focus needs to be on the required Print Conditions for the specified output device. The ChromaChecker system uses “Tracks” to define Print Conditions.

1. Device Variation E-Factor (device precision)

ChromaChecker measures the precision of any Printing Device (defined within a Track) - which we define as the ability to consistently reproduce color in the same way, across the page (within page variation- spatial uniformity), within job (Repeatability-Inter page variation), and between jobs (Reproducibility, Inter job variation). ChromaChecker provides unique targets which allow the software to compare a device to itself in the three aforementioned ways. This is critical in order to understand the characteristics of a device, before attempting to profile it. For instance, Xerox Igen3’s have proven to exhibit a 4 E-Factor (delta E) change from the first page out of the printer versus the 15 page out of the printer (due to drum imaging changes), and the profile that you get by just measuring the target on the first page out, will not provide an accurate result on any jobs that print more than 15 pages in a job. This is critical to know before you spend the effort to profile the first page, only to prepare a 1000 page job to the customer and only the first 5 pages are accurate

2. Device Deviation E-Factor (device accuracy)

One or more averaged groups of measurement files from an output device condition are compared to any Reference Print condition (CRPC) to judge accuracy (how close your device matches to a defined Reference Print condition such as GRACoL. We use an ICC profile as a source of reference printing aim points. E-Factor device deviation represents 95th Percentile ∆E (00) of your device compared to the designated reference print condition. This E-Factor defines how well your device is simulating your desired reference print condition. This tool also has a unique function called “Best Match RPC” which will use your measurement data from your device and stack rank your loaded Reference Print Conditions in order of E-Factor showing you if your device is better suited to match a different RPC (larger or smaller gamut) due to your device condition. This makes it very easy for a new user to understand what Characterized Reference Print Condition they should target.

3. Inter-Device E-Factor

In the same way that Instrument Inspector can compare your instrument to any other instrument in the supply chain, the Print Inspector can compare your output device to any other output device and Reference Print Condition. This is a function is unique to the industry, but is extremely useful. It allows a company to compare multiple output devices such as a digital presses, proofers and conventional presses and calculate the E-Factor for each device against one another AND to a Reference Print Condition such as GRACoL. This is an extremely powerful function in order to determine which device is “most off” (highest E-Factor) in order to prioritize the attention on the most “off” device to fix it and bring it into a conforming E-Factor.

 

 Manufacturing Plant E-Factor

The lowest E-Factor that a manufacturing facility is capable of producing in production. This value will differentiate companies from one another in terms of their capabilities of producing work within the E-Factor of their customer's expectations.

 

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ISO 15339 References annex for Color Tolerances, also known as TR016.

  • Level 1 reflects an E-Factor of 2
  • Level 2 reflects an E-Factor of 3
  • Level 3 reflects an E-Factor of 4.5
  • Level 4 reflects an E-Factor of 6

 

Selection of typical E-Factor™ values:

  • Expectation of very demanding corporate customers (for selected brand colors): E-Factor = 2
  • Expectation of experienced designers: E-Factor about 3

  • High-quality measurement Instruments itself:  E-Factor about 0.15 
  • Medium quality measurement Instruments itself:  E-Factor about 0.50
  • Typical inter- instrument (same vendor): E-Factor about 1,0
  • Typical inter- instrument (not well maintained various vendors): E-Factor about  2 up to 4!

  • Indigo that is well maintained: E-Factor about 4  
  • Indigo that is not well maintained: E-Factor about 7
  • Offset Press that is well “top line” maintained: E-Factor about 3
  • Offset Press that is “normal”: E-Factor in range of 4-5
  • Offset Press in sub normal condition: E-Factor in range of  6-7
  • Reference a Web to Print study on color accuracy: E-Factor Normal = 7-8
  • Proofer which is very accurate: 1- 2 E-Factor