idealliance proofing certification...

IDEAlliance Proofing Certification Program Version 19h

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December 2009

Warning This document is not a standard, but intended to be a specification specific to outline the requirements to achieve proofing certification. It is distributed for review and comment. It is subject to change without notice and should not be reproduced for distribution. All recipients of this document are invited to submit their comments for review.


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Table of Contents

Philosophy - Program Attributes ...........................................................................................................................3

Intent .......................................................................................................................................................................3

Program Components............................................................................................................................................3

Certification Categories..........................................................................................................................................3

Basis for Proofing System Certification ................................................................................................................3

Details of Hard Copy Proofing System Certification..........................................................................................4

Submission Process...............................................................................................................................................4

ADS Review and Approval ....................................................................................................................................4

Visual Inspection of Hard Copy Proofs .................................................................................................................4

Colormetric Evaluation...........................................................................................................................................4

Reporting Results ...................................................................................................................................................5

Posting Results.......................................................................................................................................................5

Details of the Monitor Proofing Certification Process.......................................................................................6

Submission Process...............................................................................................................................................6

ADS Review and Approval ....................................................................................................................................6

Visual Evaluation....................................................................................................................................................6

Colormetric Evaluation...........................................................................................................................................6

Reporting Results ...................................................................................................................................................7

Posting Results.......................................................................................................................................................7

ANNEX C - Visual Inspection Checklist................................................................................................................8

ANNEX D - Contractor Measurement Instruments ..............................................................................................9

ANNEX H - Differences Between Hard Copy and Monitor Certification ..........................................................10


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1 Philosophy – Program Attributes

1.1 Intent This specification is intended to define the proofing certification associated with GRACoL and SWOP. It is intended to comply with ISO 12647-7 with the following omissions:

• Gloss • Fade • Light fastness and resolving power • Margin information as to proof identification

1.2 Program Components The IDEAlliance Proofing Certification Program is made up of two separate catagories: Hard Copy Certification and Monitor Certification.

1.3 Certification Categories There are three paper categories in which a proofing system may be certified within this program.

• TR006 (GRACoL commercial grade 1 coated)

• TR003 (SWOP publication grade 3 coated)

• TR005 (SWOP publication grade 5 coated)

1.4 Basis for Proofing System Certification • Defined visual and measurement content to fill “normal” web or sheet fed press sheets.

• Supplied targets for certification of color accuracy and detection of artifacts.

• A select number of ISO-standard and other images.

• Characterization data sets for the certification categories specific to CIELAB values for the IT8.7/4 characterization target.

• A visual examination of proofs prior to conducting numeric evaluation. Visual examinations will follow the checklists provided in Annex C. These examinations will ensure that there are no visually unacceptable artifacts in the proof. These would include but not be limited to physical abrasions, image artifacts (such as moiré or banding), etc.

• Color measurement data generated per ISO 13655 for hard copy proofs, from the following targets;

o IT8.7/4

o IDEAlliance ISO 12647-7 2009 Color Control Wedge

• Viewing conditions based on ISO 3664 with UV content included.

• An Application Data Sheet (ADS) using the template in Annex E for each proofing system certification category.


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2. Details of Hard Copy Proofing System Certification Process

2.1 Submission Process The submission process begins with an application form (see Annex B) that must be completed and submitted to IDEAlliance, along with the entire certification fee.

• The remainder of the submission is sent to the evaluation contractor, consisting of:

• A separate ADS based on the template in Annex E, for each system and category to be certified.

• Three sets of 17x21 inch proofs using the form illustrated in Annex A. If the device cannot produce 17x21 proofs, a smaller 12x17 form is available.

• The proofs will be retained by IDEAlliance and will not be returned.

• When all required materials have been received, the submitter will receive an email indicating that the certification is ready to begin.

NOTE: The submitter may supply a proof to the Evaluation Contractor for measurement with the designated certification instrument. This will allow the submitter to determine if there is any instrumentation offset prior to submission. A nominal fee will be charged for this service.

2.2 ADS Review and Approval • Each ADS submitted will be reviewed by the Evaluation Contractor.

• Any discrepancies or omissions will be reviewed with the submitter.

2.3 Visual Inspection of Hard Copy Proofs • The Evaluation Contractor prior to a metrological evaluation will visually inspect all submitted

proofs.

• Inspection will be based on a checklist (see Appendix C). If any level 2 defects are found, a new set of proofs must be submitted.

2.4 Colorimetric Evaluation • The proof will be evaluated colorimetrically using a known, traceable (see Annex D)

spectrophotometer per ISO 15790, and compared to its respective goal characterization data set. The X-Rite iSis XL and the SpectroScan spectrophotometers are used for the certification process to measure and verify color.

• All submitted proofs must pass measurement requirements found in ISO 12647-7 or as otherwise specified.

• Proofs will be measured against white backing as per CGATS.5-2004, or the most current version.

• The CIELAB Delta Eab formula will be used.

• The following numeric criteria must be met in order for a system to be deemed to have passed certification and to be labeled as “Certified.

o The difference between the characterization data set and the IT8/7.4 target shall be average Delta Eab ≤ 1.5 for all patches. (iSis)

o The maximum difference between the characterization data set and the IT8/7.4 target shall be Delta Eab ≤ 6.0 for at least 95% of all patches. (iSis)

o Solid cyan, magenta, yellow, black shall be Delta Eab ≤ 5.0 from the characterization data set. (iSis)

o Solid red green and blue shall be Delta Eab ≤ 5.0 from the characterization data set. (iSis)


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o The difference between the characterization data set white point and the proof white point (excluding fluorescence) shall be no greater than; Delta L* +/-2.0, Delta a* +/-1.0, Delta b* +/-2.0 with a maximum Delta Eab ≤ 2.0. (iSis)

o The difference between the 50% CMY gray patch value and the characterization data set shall be Delta Eab ≤ 1.5. (iSis)

o The difference between all CMY gray patches (3, 10, 25, 50, 75) in the IDEAlliance ISO 12647-7 2009 Color Control Wedge and the reference data supplied with the strip shall be no different than; Delta L* +/-2.0, Delta, a* +/-1.0, Delta b* +/-1.0 with a maximum Delta Eab ≤ 2.0. (iSis)

o The difference between all patches in the IDEAlliance ISO 12647-7 2009 Color Control Wedge and the reference data supplied with the wedge shall be an average Delta Eab ≤ 1.5. (iSis)

o The maximum difference for each patch in the IDEAlliance ISO 12647-7 2009 Color Control Wedge between Page 1 of 2 and Page 2 of 2 (or Page 1 of 3, Page 2 of 3, and Page 3 of 3 if using the 12x17 pages) of the form shall be delta Eab ≤ 1.5. SpectroScan)

• If the numeric criteria are not met, the proof will be re-measured and if it fails a second time, a second proof will be measured. If the second proof fails, the proofing system submitter will be notified that the system has not passed certification. The certification fee allows for a second trial for each system without recharge.

2.5 Within Sheet Uniformity The variability of the coloration across the proof format is limited by the provision that the color of 9 measurement locations evenly spaced a on test object (see Annex A) after a specified stabilization period, which has been proofed without prior modification in view of the printing condition, shall have a maximum color difference of delta Eab ≤ 2 between the average and any one point.

NOTE: The Print Properties & Colorimetric Working Group defines the tolerances for the proofing system certification program. The Print Properties Colorimetric Working Group reserves the right to adjust any of these tolerances on an annual basis to reflect industry trends.

2.6 Reporting Results Results will be reported within 3 working days of the conclusion of the Colorimetric Evaluation.

2.7 Posting Results • The Evaluation Contractor will notify submitters having successfully passed certification by email. If

an update to the ADS is required, the Contractor will note that as well.

• Submitters will be provided with the certification logo and Intellectual Property Rights for use on their websites and in marketing materials.

• The submitter must provide a completed ADS to IDEAlliance in MS Word format according to the provided template. IDEAlliance will insert the certification logo, date certified and convert the ADS to PDF.

• The PDF version will be posted to the IDEAlliance SWOP/GRACoL Certified Proofing Systems online web site.


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3 Details of the Monitor Proofing Certification Process

3.1 Submission Process The submission process begins with an application form (see Annex B) that must be completed and submitted to IDEAlliance, along with the entire certification fee. The remainder of the submission is sent to the evaluation contractor, consisting of:

• A separate ADS based on the template in Annex F, for each system and category to be certified.

• An example of the monitor being certified with the system, the related computer hardware required for operation of the system and all relevant connecting cables, power supplies, etc.

NOTE: The submitter may elect to use computer hardware furnished by the evaluation contractor if such equipment is available at the time of certification. For monitor Certification, it is required that the submitters send a technician to the evaluation contractors’ site to operate the monitor and software. The evaluation contractor is available to travel to the submitter’s location to conduct the certification, but additional costs will be incurred to cover the evaluation contractor’s time and travel costs.

When all required materials have been received, the submitter will receive an email indicating that the certification is ready to begin. The submitter must schedule the certification with the evaluation contractor.

3.2 ADS Review and Approval • Each ADS submitted will be reviewed by the Evaluation Contractor.

• Any discrepancies or omissions will be reviewed with the submitter.

3.3 Visual Evaluation • All test form images will be displayed on the monitor proofing system and inspected by the

Evaluation Contractor prior to colorimetric evaluation.

• Inspection will be based on the checklist found in Annex C. If any level 2 defects are found, a new set of hardware must be submitted.

3.4 Colorimetric Evaluation Each submitter is responsible for providing a software application that automates on-screen measurement of the IT8/7.4 target for the monitor proofing system being certified. The application must provide a text readable file containing (at least) the CMYK values of each measured color in the IT8/7.4 target and the corresponding measured XYZ and L*a*b*.

The monitor will be evaluated colorimetrically using a known, traceable (see Annex D) spectrophotometer per ISO 15790, and compared to its respective goal characterization data set. The X-Rite i1 Pro spectrophotometer has been selected for the certification process.

In order for the submitted monitor example to be eligible for certification, it must pass the following uniformity requirements:

• Uniformity will be measured in nine locations on a 3x3 grid across the display. Refer to ISO 12646 for details of this test.

• The luminance uniformity relative to the center patch of the 3x3 grid must lie within a tolerance of +/- 10.0% Y at RGB=255, +/- 13.3% at RGB=127, +/- 15% at RGB=63

• The gray balance uniformity must lie within +/- 0.005 in units of CIE1976Lu’v’ for all the above levels of gray.

NOTE: Manufacturer must provide a pass/fail uniformity check with their software to ensure that a particular display is in compliance with the uniformity tolerances specified above. The system must indicate uniformity status as well as calibration status when images are viewed.


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NOTE: If the submitter provides means of correcting for non-uniformity and this correction is necessary for the system to pass certification; the procedure for enabling this correction must be defined in the ADS and the evaluation contractor will test this procedure when performing the certification process.

3.5 Colorimetric Evaluation

The following numeric criteria must be met in order for a system to pass certification and be labeled as “Certified.”

• The difference between the characterization data set and the IT8/7.4 target shall be an average Delta E2000 ≤ 2.0 for all patches.

• The difference between the characterization data set and the IT8/7.4 target shall be maximum Delta E2000 ≤ 6.0 for at least 95% of all patches.

• The solid patches cyan, magenta, yellow, red green and blue on the IT8/7.4 shall be Delta E2000 ≤ 7.0 from the characterization data set.

• The differences between the characterization data set and the paper white patches on the IT8/7.4 target shall be Delta L* +/-2.0, a Delta a* +/-1.0 and a Delta b* +/-2.0.

• The difference between the 50% CMY gray patch value and the characterization data set shall be Delta E2000 ≤ 1.5.

• The difference between all CMY gray patches (3, 10, 25, 50, 75) in the IDEAlliance ISO 12647-7 2009 Control Strip and the reference data supplied with the strip shall be no different than; Delta L* +/-2.0, Delta, a* +/-1.0, Delta b* +/-1.0 with a maximum Delta E2000 ≤ 2.0.

• The difference between all patches in the IDEAlliance ISO 12647-7 2009 Control Strip and the reference data supplied with the strip shall be an average Delta E2000 ≤2.0.

If the numeric criteria are not met, the monitor will be re-measured and if it fails a second time, the proofing system submitter will be notified that the system has not passed certification. The certification fee allows for a second trial for each system without recharge.

3.6 Reporting Results Results will be reported within 3 working days of the conclusion of the Colorimetric Evaluation.

3.7 Posting Results The Evaluation Contractor will notify submitters having successfully passed certification by email. If an update to the ADS is required, the Contractor will note that as well.

Submitters will be provided with the certification logo and the Intellectual Property Rights for use on their websites and in marketing materials.

The submitter must provide a completed ADS to IDEAlliance in MS Word format according to the provided template. IDEAlliance will insert the certification logo and convert the ADS to PDF.

The PDF version will be posted to the IDEAlliance SWOP/GRACoL Certified Proofing Systems online web site.


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ANNEX C ─ Visual Inspection Check List

PROOFING CERTIFICATION INITIAL CHECK LIST

Hard Copy Proof Characteristic Page 1 Page 2

Hickies/Voids/Scuffs/Folds ____ ____

Banding (striping or streaks) ____ ____

Moiré/Patterning ____ ____

Other ___________________________ ____ ____

0 = No noticeable defects found

1 = Defect(s) noticed but not considered significant

2 = Reasonably sure that the defect(s) would affect the measurement or image evaluation

Monitor Proof Characteristic Page 1 Page 2

Banding (a.k.a quantization errors) ____ ____

Moiré/Patterning ____ ____

Other ___________________________ ____ ____

0 = No noticeable defects found

1 = Defect(s) noticed but not considered significant

2 = Reasonably sure that the defect(s) would affect the measurement or image evaluation


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ANNEX D – Contractor Measurement Instruments

A1 Hard Copy The X-Rite iSis XL (Rev C) is currently used for hard copy proofing systems certification. The reference instrument is carefully maintained and calibrated with assistance from X-Rite.

A2 Monitor The X-Rite i1 Pro (Rev D) is currently used for monitor proofing systems certification. The reference instrument is carefully maintained and calibrated with assistance from X-Rite.


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ANNEX H – Differences Between Hard Copy and Monitor Certification

A1 Scope

This Annex intends to explain the three key differences between certification for monitor proofing and certification for hard copy proofing.

These differences are:

• Normalizing all CIELAB calculations to the white point of the display rather than standard D50 white

• The use of delta E 2000 as the metric for calculating color differences

• The use of slightly higher tolerances for average error and 100% colors

A2 Normalizing the Reference White Point of CIELAB to Display White Several studies seem to indicate that a preferred match to white balance occurs between hard copies in a viewer and images on a display when the display is calibrated to a higher color temperature than D50. This unexpected result appears to lie in the fact that the spectra of displays are significantly different than the spectra of colored inks in a D50 viewer. For example, see the references to monitor white vs. D50 in the UGRA reference below, as well as the reference below to Fairchild’s excellent book “Color Appearance Models.”

Research is underway to reconcile this discrepancy. Until a satisfactory improvement to current CIELAB calculations is determined, the IDEAlliance specification addresses this issue by defining the calibrated white of the display to be the measured white reference used in the equations for CIELAB. The normalization must ensure that the calibrated white of the display results in a value of L*a*b* = 100,0,0 much as a perfect white reflector in a D50 viewer is defined to be L*a*b* = 100,0,0. If improvements to CIELAB are successful in the future, identical measurements between white points of viewer and display should result in acceptable visual match, in which case an identical value of reference white will be used for both hard copy and soft proof CIELAB calculations.

A3 Use of Delta E (2000) Rather than Delta E (1976) The historic use of delta Eab (1976) has been reasonably successful due to the similar gamut shapes of different print media. For example, consider the following comparison between GRACoL_C1 and SWOP_C3:

IDEAlliance Proofing Certification Program Version 19

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GRACoL_C1 vs. SWOP_C3

The same is not true in comparing the gamuts of displays and the gamuts of hard copies. Consider for example the dramatic difference between a typical flat panel display used in the industry and SWOP_C3:

Typical LCD Gamut vs. SWOP_C3

IDEAlliance Proofing Certification Program Version 19

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Thus, when two print gamuts differ in a particular saturated color (such as magenta or cyan) by 10 delta E (1976), the visual impact can be significant because the error is typically in both L* and C* due to such factors as ink contamination, i.e. the ink of the smaller gamut printer is “dirtier” than the ink of the bigger gamut print condition.

By contrast, errors between the gamuts of monitor proofs and hard copy proofs often lie primarily in the direction of chroma (C*). This occurs due to a lack of RGB chromaticity as opposed to ink purity. Furthermore, the most significant clipping occurs in cyan, where lack of chroma is less visible than other colors such as red. The reduced sensitivity of the eye to error in chroma (as opposed to L* or hue) is reflected in the calculations for both delta E (1994) and delta E (2000).

A4 Use of Slightly Higher Tolerances for Average Delta E and Delta E of Solids

The slightly higher tolerances for average Delta E occur due to the fact that corrections to chromatic colors may be required due to the imperfections with CIELAB mentioned above regarding monitor white vs. D50 white. In the previously mentioned UGRA reference below, it notes that a Bradford chromatic adaptation should be performed as a result of the white point correction. Other studies indicate that corrections to CIELAB must be determined in chromatic colors (see Shaw and Fairchild below, as well as Kodak patent #7,209,147 for an in-depth discussion). To account for this phenomenon, slightly higher tolerances must be used for both average delta E and the delta E of solids. It should be understood that these slightly larger tolerances will be reduced when improvements to CIELAB have been confirmed, along with an objective specification and tolerance for white point.

A5 References

User’s Guide and Technical White Paper for the UGRA Display Analysis and Certification

Shaw. M. and Fairchild, M.D. Evaluating the CIE 1931 color matching functions Color Research and Application 27, 316-329 (2002)

US Patent #7,209,147 “Correction Techniques for Soft Proofing”

Fairchild “Color Appearance Models,” Addison-Wesley, 1997, pp. 188-189

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