Some observations when profiling budget level glossy papers

[Ink stained Fingers]

There is another property of inkjet papers which varies quite a lot between them - it is the contents of optical brightener additives - OBA's. OBA's are effectively a type of dye ink which fluoresces when activated by UV light - close to the visible blue light. The ink emits the received energy at a lower frequency - typically at light blue but you can get such inks fluorescent at other colors as well, they are typically used for decorative effects under black light - posters and such.
What do you get when you profile a paper which contains such OBA's - you get a spectral distribution for the white paper spot like this one

The XRite i1Pro2 spectro measures the color spots with different measuring conditions M0 - M1 - M2
which include or exclude illumination with UV-light. Please see further explanation for the measurement modes here in the XRite document
https://www.xrite.com/-/media/xrite...ctor_what_does_it_mean/l7-510_m_factor_en.pdf

Both the M0 and M1 modes include the use of UV light during measurement with a somewhat different intensity - M2 excludes all UV light. You see that the reflectance of the red and magenta lines are above the level of one - the additional energy comes from the blue fluorescent light .
The XRite i1Profiler software displays the spectrum for the 3 measuring conditions and adds the numerical values below the diagram. The L-luminance does not effectively change much between M0 and M2 - the -b color value - the hue - changes from -1.96 to -10.27 which is significant and directly visible. The diagram above and the data belong to the LS250 glossy paper used above in the gamut comparison.
And now a problem becomes apparent - how should papers with such different white points - under different viewing conditions with or w/o UV in the illumination - be profiled - for indoor or outdoor use.
You should technically create different profiles for different viewing conditions but about no paper supplier would do that - you might get the profiles tuned for the D50 or D65 light conditions at most but not for the M0/M1 or M2 UV conditions. This leads to the effect that canned profiles are a kind of averaging both viewing conditions. And the problem is getting worse because the OBA's do the same as the other dye inks - they fade and loose their effect over time.
The XRite i1Studio profiling package comes with a spectro which just uses the M2 measuring method and creates the profiles accordingly, this implicitly implies that such profiles are to be used for prints mainly viewed indoors - with a low UV level overall. The prior ColorMunki package used practically the same M2 spectro not taking any UV into account.

The I1 profiler spectros and software - i1Pro - I1Pro2 - i1Pro3 let you select the measuring condition
at the time you create the profile .
Most inkjet glossy papers come with OBA's and it is difficult to find one without; I'm wondering why paper companies are doing that - I question very much that most inkjet prints are viewed in an ambient light with much UV at all .

I'm only aware of one paper which does not have much OBA's at all , this is the HP Premium Plus Photo Paper which I use for comparison in this thread, and elsewhere as well.

 

[Ink stained Fingers]

This is the spectrum of the white point of this HP paper

The hue - the b-value just changes from -1.71 to 0.20 for the hue, that is only visible under good viewing conditions, and the overall luminance of this paper is 97.2 vs. 94.4 of the LS250 paper, the HP paper looks visibly whiter than the LS250 paper.

The i1Profiler software offers an data analysis tool to compare data of patch sheets and can do various calculations e.g. calculating color differences - DeltaE - with different formulas. These formulas got modified because the original version does not match well larger deltas with the visual perception of those. But I just use the original version for this posting since we are not doing visual assessements really.

This is a crop of this data analysis mode and shows the colorimetric differences between the Mo and the M2 mode - dataset A and dataset B and highlight those spots with the highest deltas with a yellow box around the resp. spot, and the max value with a red box. The paperwhite spot of the LS250 paper varies by a DeltaE of 8.744 which is significant, and it's not just the paperwhite spot affected but more or less all lighter colors - where the color of the ink mixes with the color of the underground.

If I do the same display with the data for the HP paper I get this display

The DeltaE between the M0 and M2 mode - with and w/o UV - is just 1.999 which is the highest delta value in this dataset and not visible in normal prints.

 

[Ink stained Fingers]

But the missing deep blacks lead to crunched shadows. A lot of people don’t look at is, as long as the print has bright and saturated colors.

Let me just give you a few numbers for blackpoints of papers I have tested on a L1800, numbers may vary with other printers and/or driver settings

Hayatec - Ebay ___________3.7
LS250_____________________9.4
LS270_____________________9.3
Druckfuxx - Ebay_________5.4

These are all budget level cast coated papers

Sihl - Aldi_________________4.5
Canon PT-101____________3.1 which performs very well - very good black point - large gamut - best fading performance
HP Premium Plus_________5.5 no OBA's

which all are PE/RC papers

Baryta Glossy Mediajet___8.4

 

[stratman]

Seems ironic that the HP paper without all the OBA's is whiter than the LS250 paper that has all the OBA's.

 

[Ink stained Fingers]

Seems ironic that the HP paper without all the OBA's is whiter than the LS250 paper that has all the OBA's.

The secret is in the coating - there are probably some ingredients in the HP paper which are too expensive for a budget paper - the HP paper is 10x more expensive

 

[Ink stained Fingers]

There is another difference between a budget level paper and the HP Premium Glossy paper - the look of the gloss. It is not that easy to find a way to measure such differences but there is a simple way to do a comparison - place a sheet flat onto a table which is a meter or 2 away from a white or uniform wall, use a laser pointer , point onto the paper on the table and watch the reflection on the wall. You get this for the
LS250 paper

and for the HP Premium Plus paper

This reflective pattern is much more defined than the pattern of the LS250 paper which is hazier overall and wider. If you keep distances constant you could go and measure the different diameters and/or take an image to compare with other papers - you'll detect interesting variations.

You can do this test as well on printed areas, and when you do that with prints with pigment inks you may find gloss differences between colors in the reflective pattern or differences between printed and unprinted areas, the ink , the solvent changes the surface structure.

 

[maximilian59]

The DeltaE between the M0 and M2 mode - with and w/o UV - is just 1.999 which is the highest delta value in this dataset and not visible in normal prints.

This brings me to the question with larger gamuts. If you compare the colors at the boundary of two gamuts, where one is maybe 10% larger than the other, are the deltaE great enough to see a difference?
It is just about the discussion, about large gamuts. Sometimes I see with Iccview or ColorSync, that a larger gamut from let’s say 700.000 to 770.000 is not visible on a print. Especially when the enlargement goes over nearly the whole surface. This are small offsets along all boundaries.
Otherwise same figures of gamuts can lead to very different prints, when the volumes have a significant different shape. Good example is comparing sRGB with a gamut of a printer profile. Most of the time none of them covers the other. It’s even worse with larger gamuts as AdobeRGB.

 

[maximilian59]

I'm wondering why paper companies are doing tha

The cheaper the paper basis is, the more away from white it is. Normally the paper is more to yellow. To compensate OBAs are used, as it is also done long in textile industry. You don’t need much UV to see the effect. A fluorscent lamp or even LEDs are emitting UV. If you handhold the paper it is visible. Behind glass you normally wouldn’t see it. Cheap papers are not made for high end presentation in a gallery. You have this prints on the desk, the fridge, pinned to the wall or just in a box or album. They are viewed everywhere And then thrown away. Who bothers about yellowing in 20 or more years? And even when they do, hey they are old pictures then and can be looking old. The problem might be the ink used, which may have started fading.
I don’t see that big problem with OBAs with more than 99% of my prints. There are economic papers with not that much of brighteners as the one above. Luckily we have the choice to use what we want for what purpose we need it.
Every photographer knows the sentence: The best camera is the one you have with you.
For the ones who print: The best print is the print you made.
Cheers,
Maximilian

 

[Ink stained Fingers]

Cheap papers are not made for high end presentation in a gallery. You have this prints on the desk, the fridge, pinned to the wall or just in a box or album. They are viewed everywhere And then thrown away.

I don't typically do such a full assessment of a budget paper as described above when I get a pack of those, I just use them for similar purposes as you describe.

Who bothers about yellowing in 20 or more years?

OBA's fade as fast as some dyes and contribute to the overall fading with a yellowing effect but that doesn't matter in the longer run. I just don't see the need for them in almost every paper. About every I1Studio/ColorMunki user would be better off without them when profiles are calculated for the M2 condition only.

 

[Ink stained Fingers]

Printer gamuts are pretty different from the standard sRGB or AdobeRGB color spaces, but that is different from the OBA effects. The effects of OBA's are not just visible at the top close to the white point but down almost to a mid luminance of L=50 - the shift in the -b direction

This at the top - blue for the M0 condition - red for the M2 condition w/o OBA

and this at L=60, the light blue tone of the paper is still shining through

There is some gain of the volume in the -b direction but some loss for the M0 profile in the lower part, not visible in this display, MonacoGamutWorks calculates some overall volumetric numbers - 1145547 for the M0 profile vs. 1142237 for the M2 profile