GRACoL on Digital Toner Press

[arossetti]

I'm having an issue with my printer in the max cyan, max M,Y, K aims are fairly accurate. Cyan however has a low L* & A* value both raw and through my profile. My aim is ISO12647-8 using GRACoL2013, however my cyan has a DeltaEab of 8.5 and a DeltaHab of 7.5.

What can I do to my printer to fix this? Looking at the raw data of my printer the GRACoL aim for cyan is out of gamut.

 

[Stephen Marsh]

Is this media dependent?

Fusing time/speed/temp related?


Stephen Marsh

 

[arossetti]

Let me check some other stocks and also try lowering my fuser temp on the stock in question. Thanks for the suggestions.

 

[rich apollo]

arossetti,
Do you have an ICC profile of the printing condition, or P2P measurement data, or simple step-wedge measurement data that you can share?

If your cyan is dark and greenish (or not warm enought), how are your RGB overprints?

 

[arossetti]

Below is a link to a folder with all the supporting documents.

The ICC profile we are using for our destination, the CGATS info that we used to create said profile, the Colorport and i1Profiler workflow (wasn't sure which was needed) that we used as a target for the CGATS.

The analytical pdf report shows how stable the printer is, this information was created from analysing the CGATS info we used for the destination profile creation.

Finally the verify pdf report is the analysis of our GRACoL wedge when trying to print to our CRPC-6 2013 aim.

Our overprints in green are also an issue due to the cyan being off. Really it is the A* value of our cyan max density which is the real issue, causing our blues to be very warm, especially out of gamut RGB blues.


https://drive.google.com/folderview...RhVW5TdVpiU2psNmY1MURtb2ZpMko2ZEE&usp=sharing

 

[arossetti]

Below is a link to a folder with all the supporting documents.

The ICC profile we are using for our destination, the CGATS info that we used to create said profile, the Colorport and i1Profiler workflow (wasn't sure which was needed) that we used as a target for the CGATS.

The analytical pdf report shows how stable the printer is, this information was created from analysing the CGATS info we used for the destination profile creation.

Finally the verify pdf report is the analysis of our GRACoL wedge when trying to print to our CRPC-6 2013 aim.

Our overprints in green are also an issue due to the cyan being off. Really it is the A* value of our cyan max density which is the real issue, causing our blues to be very warm, especially out of gamut RGB blues.


https://drive.google.com/file/d/0B2Fu9Tub76LDd3JuS2sydUlFNzg/view?usp=sharing

Fixed link

https://drive.google.com/folderview?id=0B2Fu9Tub76LDfkUxcXF4a0NhSGFCZkQzRDFHN0RhVW5TdVpiU2psNmY1MURtb2ZpMko2ZEE&usp=sharing

 

[rich apollo]

I get a different result converting 100% cyan from GRACoL2013 to your x800 profile in Photoshop than what your colorbar measurements show. How are you handling the conversion of the colorbar?

Comparing GRACoL2013 to your x800 profile does not indicate a gamut issue. I don't see any big problems on the calibration - no hooking of primaries and secondaries. To me this looks like an issue in the conversion.

Try performing the conversion of the colorbar in Photoshop and then bypassing the color conversions on the RIP and see what kind of result you get.

 

[arossetti]

I get a different result converting 100% cyan from GRACoL2013 to your x800 profile in Photoshop than what your colorbar measurements show. How are you handling the conversion of the colorbar?

Comparing GRACoL2013 to your x800 profile does not indicate a gamut issue. I don't see any big problems on the calibration - no hooking of primaries and secondaries. To me this looks like an issue in the conversion.

Try performing the conversion of the colorbar in Photoshop and then bypassing the color conversions on the RIP and see what kind of result you get.

My destination profile is depending on my source profile to limit the gamut of the device. So if I look at the wedge in photoshop and compare GRACoL2013 to my destination X800, the x800 will move cyan further out to B* -57. But through my DFE the source profile of GRACoL2013 would limit the max cyan back to B* -50.

Does that make sense? Is that the conversion issue you are seeing?

 

[csawatzki]

I am not sure if anyone has mentioned this.

Remember that if we are discussing an iGen4 or older, it will not reach the Gamut of true Gracol. The "Gracol" standard for that device is a Digital Gracol. It is not the same thing....

Cory Sawatzki
Spotlight Print Consulting
[email protected]

 

[rich apollo]

My destination profile is depending on my source profile to limit the gamut of the device.

Not how I would explain it, but close enough for this conversation.

So if I look at the wedge in photoshop and compare GRACoL2013 to my destination X800, the x800 will move cyan further out to B* -57. But through my DFE the source profile of GRACoL2013 would limit the max cyan back to B* -50.

Does that make sense? Is that the conversion issue you are seeing?

Not quite.

If I'm getting an accurate conversion of your colorbar data, your cyan patch is L*=54.17, a*=-30.4, b*=-50.69.

If I go into Photoshop and create a 100% cyan patch in the GRACoL2013 colorspace, then I convert it to your x800 colorspace, (relative colorimetric) I get 57, -36, -49. That's brighter and bluer than what you measured.

I think that the DFE is performing an odd conversion. So, by converting the colorbar in Photoshop and then printing it with no color management, only calibration, you can test that idea. If everything is working properly, then theoretically you should get similar (not identical, but similar) results using both methods.

 

[arossetti]

When I convert 100% cyan in photoshop from GRACoL2013 to my destination profile I get 55, -32, -49. Using both the Adobe engine and Microsoft using relative or absolute (my paper seems to be correct).

How are you getting L57 A-36? That would solve this issue.

 

[arossetti]

The 55,-32-49 file prints 54.5,-31,-49.8. Seems to print correctly.