Profiling and such - some observations

[Ink stained Fingers]

Please let me add another observation with different papers, differences between papers - PE type and castcoated type papers have been discussed elsewhere in detail in regards to their fading performance, papers of different suppliers are not alike - even of the same type , showing differences in their fading performance or the gamut, with the same ink on the same printer.
Let me show you what you can get at the budget end,
I'm using here a cc paper 160 gr with coating of both sides for double sided printing , by a distributor Pearl in Germany, and another cc paper 155 gr double sided as well, I called it IP155 , I don't know the vendor anymore.
These are the gamuts at mid luminance L=50%

red IP155 green Pearl 160
So far so good, that's typical gamuts, not much variance.
But it looks very much different at the dark end

This is the plot at L=17%, the red gamut plot is much wider, there are many more darker colors availlable for print, and the black point of the IP155 is at L=12%. These differences are
directly visible in prints - the black is darker, the prints show more contrast and more detail in the shadow areas (with the same ink set).
This is a view of the 3D gamut display showing clearly the differences at the bottom of the
gamut volumes

And what else ? the IP155 paper was even cheaper than the Pearl paper - with better overall
performance for this type of double sided prints, fading does not matter much in an album (unless a budget ink even fades in the dark...)

 

[Ink stained Fingers]

I'm using an i1Pro for profile generation together with the i1Profiler software, this software has several operating modes if you connect a spectrometer like the i1Pro2 or iSiS scanner which allows you to read the color patches with regular light and UV light separately to precisely catch the influence of optical brighteners. The software claims to do an automatic OBA correction if you use the previous generation of spectrometers - the popular i1Pro, this comes in two versions - UV cut - one which filters out the UV contents of the lamp/patch illumination so that OBA's will not be activated in the paper and the sensor will not read any of such data. And there is another version which comes without this UV filter, remaining UV light of the lamp will activate the OBA's and the sensor will read slightly other data. I'm using the i1Pro without such filter, the unit is already heavily used, and I was looking for a backup which I found on Ebay, this time a unit with the UV cut filter. This gave me the chance to compare the differences in profiles with these two units .
I tested and profiled the Aldi/Netbit paper which comes with OBA's together with the HP Premium Plus (CR674A) paper which does not contain OBA's, and I created profiles with both spectros to compare.
The Aldi/Netbit and the HP paper are both 300gr papers, both with a very good and uniform gloss. When holding both papers together the HP paper looks slightly lighter than the Netbit under lamp light, the Netbit paper looks slightly yellow in comparison. It is different under sunlight, the Netbit paper is slightly brighter than the HP paper which is caused by the OBA's.
I now can measure the white papers with both spectros, both come with a calibration tile which all create some measurement variations - between instruments, between these calibration tiles, between measurements with the same spectro at the same spot and variations of the papers at different spots. I did not go through a myriad of measurements including statitical analysis, I did not get my spectros factory calibrated before these tests but I got some data which appear to be consistent. These are the L(ab) values of the measured white points

____________________ Netbit Paper__________HP Paper
i1Pro___________96.8(-.8 -2.1)____95.6(1.0 -2.0)

i1Pro UV Cut____94.0(-1.0 .9)_____95.6(-1.5 -.9)


So far so good, the Netbit paper shows a lightness and color difference if measured with or w/o the OBA's active.

I created 2 profiles each for the 2 papers with the data of both spectros to check whether there
is any visible difference at the end in printouts using one or the other profile.

Hows do the profiles compare:

That's the Netbit paper , profiles shown at L=50 with both spectros, red is the line for the UV cut unit, differences are small, and the diagram looks rather similar for the HP paper, the ink denstiy here is already quite high and the paper is not shining through very much.

Looking to the darker end of the profiles it looks like this

The red line is for the Netbit paper, the blue line for the HP paper, this at L=25, here is no influence of the OBA's at all anymore. Both papers have about the same black point at L=5

How does it look at the lighter end of the gamuts, at the top

This is the Netbit paper at L=93, the smaller gamut line is measured with the UV Cut spectro, the wider line shows the additional room the OBA's add here, the ink coverage is very thin, the paper surface remains visible for the measurement.
Now I have 2 profiles each for the 2 papers, and I printed some test images whith these profiles on both papers to see whether there is any visible difference in the printouts, I must admit I did not see any - the colors are the same, looking to the prints indoor and outdoor under sunlight or overcast conditions, I checked the printouts several times but I cannot see a difference whether a printout is created with this or that instrument, the only small visible difference remains between the papers, their whites are slightly different as mentioned above already.