Printer Profile Validation: M1 vs. M2 and ΔE2000 Evaluation

[know]

Clarification:

My preliminary investigation suggests that NCM is misconfigured. Strip indicators, spacer color and size, and patch width and height do not appear to be contributing factors.

What do you mean by NCM? I might just be too inexperienced to know what you refer to...

Knut

 

[itsab1989]

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

Although I am not 100% sure maybe the issue is the very tight space between the patches and the other element on the sheet. The measurement should start and end on paper white so everything can be recognized correctly. So maybe it helps to turn off the colored strip and the markers.

 

[know]

Although I am not 100% sure maybe the issue is the very tight space between the patches and the other element on the sheet. The measurement should start and end on paper white so everything can be recognized correctly. So maybe it helps to turn off the colored strip and the markers.

You are totally right! I did not think of that...

You have to change the helper markers to have only 2 markers, not three, or turn them off. Then you will not have that one marker in the way that might prevent the instrument to end on a white patch... Look in Create Chart tab, under manual mode, then scroll down to the helper markers in the Expert Options frame, see below image. The presets made inside ChromIQ have 13mm bottom margin, minus the 4 mm used by the helper markers. This is just enough to stop the i1Pro unit on the white patch. I see you have used some other created patch layout someone made, and it seems there is not enough space at the bottom margin. If you do the above, you should get more space for the strip-end, of you may of course use the in-built presets.

Presets:

 

[jctay]

What do you mean by NCM? I might just be too inexperienced to know what you refer to...

Knut

NCM = No Color Management
A term frequently found in older forum discussions.

[ Reference ]

 

[pharmacist]

I second Knut with those markers on small paper sizes (like 10x15 cm photo cards) to disable those markers, as it often throws errors when scanning those minitature targets as the spectro will end on a black stripe and throws an error that too much patches are detected (or in some cases not enough patches).

On the left (create test chart), you can see "expert options": click on the arrow button to open this menu:

scroll down until you see this:

uncheck "Print helper markers" and press the "generate chart" again to obtain this:

those tiny marker stripes are now gone, or you can reduce to only 2 markers so the scanning eye will be between two marker stripes (which is maybe a better compromise), ensuring the spectro will certainly begins and ends on paper white.

You can elongate those marker stripes (here from 2 to 8 mm):

 

[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


Edit:
I might have skipped some steps here, but to read more about verification runs, read the Help Cards (click on the question mark in the corner) for "Getting Started (a tour of ChromIQ)" and "Check a finished profile (verification run)":
View attachment 19391
View attachment 19392

Thanks.

Cheers,
Knut

ChromIQ Printer Profile Verification Workflow for 4″ × 6″ Photo Printers

Preparation
a. Profiling Chart: 576 patches; builds the custom printer profile, Profile A
b. Verification Chart: 192 patches; checks how accurately Profile A reproduces color

Step 1: Build Profile A
1. After creating the chart, select Print Chart. The Run Type is set to Profiling by default.
2. Generate and print the 576-patch chart with color management disabled.
3. Allow the print to dry, then measure all patches.
4. Go to the Build Profile tab and click Build Profile. Refine the profile as needed.
5. Install Profile A in the operating system’s profile folder so it can be used in the print workflow

Step 2: Create the Verification Chart
6. Without closing ChromIQ, return to the main menu and click Create Chart.
7. Change Run Type to Verification.
8. Select From Profile Gamut.
9. Load the 192-patch set and select the right preset if needed.
10 Generate the verification chart.

Step 3: Print the Verification Chart
11 Print the chart with color management disabled.

Step 4: Measure the Verification Chart
12 Change Run Type to Profiling to enable measurement of the printed chart.
13 Measure all 192 patches and save the measurement results.
14 Build profile for the Verification Chart (necessary?) -- Q1

Step 5: Import the Verification Chart measurement file
15 After importing the measurement results, do I need to change the run type to Verification? -- Q2

Import measurement -verify

Below are excerpts from the files:

Quality_Check_1_CP1500-576p-ChromIQ.txt
Profile Quality Assessment: Excellent
Average ΔE00 0.56 | Largest ΔE00 2.60
12 of 585 patches (2.1%) are above your limit of ΔE00 2.0.
Your profile is excellent. Both average and peak colour errors are very low — typical for a well-measured printer/paper combination.

Refine_Strips_1_CP1500-576p-ChromIQ.txt
# CHROMIQ_REFINE_STRIPS_V1
# Strip MaxDE
18 2.60
21 2.55
39 2.56
# Patches above the limit (patch-by-patch guidance):
#P 18D 2.60
#P 21J 2.55
#P 39C 2.56

Quality_Check_1_CP1500-576p-ChromIQ-verify.txt
Profile Quality Assessment: Good
Average ΔE00 0.64 | Largest ΔE00 4.80
11 of 192 patches (5.7%) are above your limit of ΔE00 2.0.
Your profile is good overall (average ΔE00 0.64), but one or more individual patches have higher errors (peak ΔE00 4.80). Most colours will reproduce accurately; the outlier patches may cause subtle shifts in specific colours.

Refine_Strips_1_CP1500-576p-ChromIQ-verify.txt
# CHROMIQ_REFINE_STRIPS_V1
# Strip MaxDE
3 4.43
8 3.96
11 4.41
14 4.80
# Patches above the limit (patch-by-patch guidance):
#P 3F 4.43
#P 8G 3.96
#P 11J 4.41
#P 14D 4.80


I don't seem to be able to make any further progress, as I seem to be going around in circles.
Any help would be greatly appreciated.

 

[know]

ChromIQ Printer Profile Verification Workflow for 4″ × 6″ Photo Printers

Hi @jctay,
Thanks for testing to verify a profile

I have a few comments for you.

Step 4: Measure the Verification Chart
12 Change Run Type to Profiling to enable measurement of the printed chart.
13 Measure all 192 patches and save the measurement results.
14 Build profile for the Verification Chart (necessary?) -- Q1

line 12 is wrong. You have to keep run type set to Verification. All you do in any of the tabs now belong to the verification run. You then select the Measure tab and start measuring of the 192 patch chart you selected and printed for verification (point 13). Point 14 is then wrong... you do not create a profile from a verification measurement. That is only done for the profiling run (after you completed measurement, when run type is set to Profiling, which is the 572 patch chart you chose to use).

Step 5: Import the Verification Chart measurement file
15 After importing the measurement results, do I need to change the run type to Verification? -- Q2

You do not need to import anything. Your image shows you are in Run type=Profiling. You only need to measure that once, and after you made the profile, you can run the Check & Refine (see example screenshot below) for the profile you made to check if you want to refine the existing measurement to improve the first measurement and get a better profile. The "Guide Me Through Refinement" button will help you with that process...

After you have finished the steps:
Measure --> Build profile --> Analyse Quality --> Refine --> Build profile --> Analyse Quality
to your harts content...

--> Then you change to Run Type = Verification
--> Select / create a chart in Create Chart
--> Select From Profile's Gamut and make sure colors are picked for the verification chart that are within the profiles gamut, then press Generate Chart.

If you wonder how the patches are spread on the chart according to your profile, then select tools --> "Show patch distribution (3D)"

Then select in the "Show" pulldown as shown in the below image.

Then,
--> Print the chart "raw" (without color management) (still Run Type = Verification) -->
Then measure the chart in Measure tab (still Run Type = Verification)

Before you start measurement the Verification field in the the Run Bar at the top says "New verification...". When you start measuring you will see the Verification field get a date and time, like this:

This is the date and time you performed your verification measurement.

When you are finished measuring, and inspecting any red highlighted patches, and possibly re-measuring some strips to assure they are correct and not mis-reads, then your verification measurement is done.

Now you can to to tools --> Measurement Report

and generate reports as you like. Here is an example screenshot.

- Select a report type, or use the default.
- Add some or all verification runs you have made for your profile over a long time (to get trend graphs), but you have now only one.
- Select "Show detailed data for each run" to include details in the report.
Click Edit Limits button to learn about the metrics that each limit set (Judged against) is using, and change them as desired (if your experience tells you another limit is needed).
- Generate Report to show the selected report in the bottom half of the window.
- Press "Save report as PDF" to save it and print it. Default save-location is usually correct according the run you are reporting one in your project.

Attached is an example of how a measurement report can look like.


This whole process is graphically illustrated in the Help window, under Help Card "Getting Started":

All these steps are described in the following help cards:

Hope this helps and that you will successfully create a verification. Do tell us the result
Thanks...

Cheers,
Knut

 

[jctay]

"line 12 is wrong. You have to keep run type set to Verification. All you do in any of the tabs now belong to the verification run. You then select the Measure tab and start measuring of the 192 patch chart you selected and printed for verification (point 13). Point 14 is then wrong... you do not create a profile from a verification measurement. That is only done for the profiling run (after you completed measurement, when run type is set to Profiling, which is the 572 patch chart you chose to use)."

Measurement cannot be started. When the “START MEASUREMENT” button is clicked, the program switches back and forth between these two screens.

screen 1

screen 2

 

[jctay]

Switched to run-type: profiling to reconfirm the i1Pro connection. The connection is working perfectly.

 

[itsab1989]

It seems you are at run 8 already. You have to stay at the run number you made the profile from. Only change to verification instead of profiling.