Printer Profile Validation: M1 vs. M2 and ΔE2000 Evaluation

[jctay]

Questions on Custom Printer Profile Validation and Measurement Conditions

I would appreciate some advice on the best approach for validating a custom ICC printer profile, particularly regarding analytical verification and measurement conditions.

1. Analytical Validation vs. Visual Evaluation

When validating a custom printer profile, do you normally perform an analytical evaluation by comparing the measured ΔE2000 values against the ColorChecker 24 (CC24) reference values, or do you rely primarily on visual evaluation of the printed target?

In particular, is there a generally accepted ΔE2000-based methodology or tolerance for determining whether a custom printer profile is performing satisfactorily?

2. Appropriate Measurement Condition for Profile Validation

I created my printer profile using M1 measurements. However, when subsequently measuring the printed CC24 target for validation, I have noticed that M2 (UV-cut) consistently produces lower ΔE2000 values than M0 or M1.

This raises a question about which measurement condition should be used for profile verification.

Should validation be performed using the same M1 measurement condition used to create the profile, so that the verification is consistent with the profiling data?

Or is it technically valid to use M2 (UV-cut) for validation if it produces a better numerical agreement with the CC24 reference values, even though the ICC profile itself was built from M1 measurements?

I am particularly interested in understanding whether the measurement condition should be considered part of the profiling/validation chain, or whether the validation condition can be selected independently based on which condition provides the most meaningful assessment of the printed colors.

Any practical experience or recommendations would be greatly appreciated.

 

[jctay]

My Findings

After measuring the CC24 target, I observed that the ColorChecker Classic patches yield essentially identical spectral and colorimetric results across M0, M1, and M2 conditions. This is expected due to the absence of Optical Brightening Agents (OBAs) in the target.

In contrast, the CP1500 print media contains OBAs. Therefore, I believe that validating the printer profile by comparing the printed CC24 target against the ColorChecker reference data is best performed using M2 (UV-cut) measurements. This minimizes OBA influence, providing a more consistent and reliable baseline to match the non-OBA reference data.

 

[jctay]

Establishing CC24 Reference Data Under M0/M1/M2 Measurement Conditions

Should we establish new reference datasets based on actual CC24 measurements acquired under each measurement condition (M0, M1, and M2)?

The CC24 reference data provides a convenient benchmark for comparing the measured colour values of a printed validation target during printer profile validation.

However, if the printed validation target is measured under condition M1 but the results are compared against an existing CC24 reference dataset that was acquired under a different measurement condition, discrepancies may arise due to differences in measurement conditions.

Would it therefore be more appropriate to establish a new CC24 reference dataset? This would help ensure a more consistent and meaningful comparison during profile validation.

 

[know]

Hi @jctay ,
This is interesting. Since you obviously have good thoughts and experience in correct validation of profiles, could I ask you to test the Verification feature on ChromIQ? Would you do the community this favour?

The hope is that this verification step will give detailed test data proving a good quality profile. Your help and sharing the results would be highly appreciated. Maybe this would satisfy your need for proving your profile's quality? Tell us what is missing please.

Do the following:

1. After a profile is created a change the Run Type parameter from Profiling to Verification,
2. select a chart (make one or select a preset). Help is given on which charts to select from the presets for verification, based on metrics that are tested in the Measurement Report, using the button "Which presets can be used for verification?" under the "Select preset" pulldown in the Create Chart tab (manual mode or "From Profiles's Gamut" mode).
3. After deciding on a chart, click on From Profile's Gamut to fill the chart with colors that the profile can reach, press Generate Chart.
4. Print that chart "raw", without color managemnet, as the colors in the chart already has the profile applied to them.
5. Measure the chart. Measure through the whole chart, and then check if there are any red highlighted patches (the neighbour-check may change highlighted patches as more measurements are completed). Re-read patches that are red, or those you find suspect based on the information given when hovering of a patch.
6. When measurement is completed, Open the Tools --> Measurement Report. Make as many reports as you want, and any type you want. There are two ISO 12647 report types with accompanying limit sets. Each limit set (the "judged by" parameter) has a defined set of metrics that is tested, or you may choose which metrics to include, and which limit values are acceptable. The ISO 12647-7 and ISO 12647-8 limit sets, for the "Contract proof check" and "Validation print check", have fixed thresholds given by the ISO 12647 standard, but using the Custom ISO limit sets you can define whatever you like for these also.
7. Print the report as PDF, as you wish.

Use the latest beta in: ChromIQ releases

Thanks.

Cheers,
Knut

 

[jctay]

Hi @jctay ,
This is interesting. Since you obviously have good thoughts and experience in correct validation of profiles, could I ask you to test the Verification feature on ChromIQ? Would you do the community this favour?

The hope is that this verification step will give detailed test data proving a good quality profile. Your help and sharing the results would be highly appreciated. Maybe this would satisfy your need for proving your profile's quality? Tell us what is missing please.

Do the following:

1. After a profile is created a change the Run Type parameter from Profiling to Verification,
2. select a chart (make one or select a preset). Help is given on which charts to select from the presets for verification, based on metrics that are tested in the Measurement Report, using the button "Which presets can be used for verification?" under the "Select preset" pulldown in the Create Chart tab (manual mode or "From Profiles's Gamut" mode).
3. After deciding on a chart, click on From Profile's Gamut to fill the chart with colors that the profile can reach, press Generate Chart.
4. Print that chart "raw", without color managemnet, as the colors in the chart already has the profile applied to them.
5. Measure the chart. Measure through the whole chart, and then check if there are any red highlighted patches (the neighbour-check may change highlighted patches as more measurements are completed). Re-read patches that are red, or those you find suspect based on the information given when hovering of a patch.
6. When measurement is completed, Open the Tools --> Measurement Report. Make as many reports as you want, and any type you want. There are two ISO 12647 report types with accompanying limit sets. Each limit set (the "judged by" parameter) has a defined set of metrics that is tested, or you may choose which metrics to include, and which limit values are acceptable. The ISO 12647-7 and ISO 12647-8 limit sets, for the "Contract proof check" and "Validation print check", have fixed thresholds given by the ISO 12647 standard, but using the Custom ISO limit sets you can define whatever you like for these also.
7. Print the report as PDF, as you wish.

Use the latest beta in: ChromIQ releases

Thanks.

Cheers,
Knut

I’ll definitely give it a try!

Meanwhile, I encountered difficulties measuring the 192-patch chart, as data from certain strips could not be captured. In contrast, the 576-patch chart was measured without any issues.

I randomized the patches, but it didn't really fix the issue.

Instrument: i1Pro 3
Printer: CP1500 4 × 6-inch dye-sublimation photo printer (Glossy)

Chart 192 Patches 10x15 cm
ArgyllCMS 576-patch target + 64 greys

 

[know]

I’ll definitely give it a try!

Meanwhile, I encountered difficulties measuring the 192-patch chart, as data from certain strips could not be captured. In contrast, the 576-patch chart was measured without any issues.

I randomized the patches, but it didn't really fix the issue.

View attachment 19390

Instrument: i1Pro 3
Printer: CP1500 4 × 6-inch dye-sublimation photo printer (Glossy)

Chart 192 Patches 10x15 cm
ArgyllCMS 576-patch target + 64 greys

Hi @jctay,

You are not giving any information on what went wrong, so it will be hard to give advice.

If you compressed the ChromIQ project, or the run in the project, with the problematic measurements that would help, and when you report bugs, the log-file usually helps a lot.

Go to Preferences window and Paths tab, there you will have the path to the log file and a button to open the folder. Then attache these in a post.

More detains on exactly what you did when the problem happens is also very important, and possibly screenshots of what happened on-screen when you say strips could not be read/captured.

Thanks,
Knut