Does the whitness of paper impact Gamut

[issa]

Does the whitness of paper impact Gamut ? I beleive it does and just wanted amore experienced answer.

I download Hahnemuehle Fine Art Baryta profile or Epson 3880 from the Hahnemuehle website and notice that their white point is much higher than I have ever been able to acheive, I have several packs and different sizes of HFAB paper, and did some tests on all, and did not come close to anything as in their profile.

Is it possible that they used a very white paper with lots of OBA, or have altered the white point / output profile.

[Mussi_Spectraflow]

Does the whitness of paper impact Gamut ? I beleive it does and just wanted amore experienced answer.

I download Hahnemuehle Fine Art Baryta profile or Epson 3880 from the Hahnemuehle website and notice that their white point is much higher than I have ever been able to acheive, I have several packs and different sizes of HFAB paper, and did some tests on all, and did not come close to anything as in their profile.

Is it possible that they used a very white paper with lots of OBA, or have altered the white point / output profile.

The White point certainly affects gamut since it represent the upper point of the gamut map. Depending on whether they created the profile using a spectrophotometer with a UV cut filter this could affect the white point's L* value by a little bit, but will certainly affect the a*/b* values, making the paper appear more blue or yellow, which will slightly alter the gamut, most noticeably if you ever use an absolute colorimetric rendering. It is also possible that they altered the white point, some manufacturers will do this, although it would be odd if they did.
When you say that you were not able to match the white point of their profile, are you just taking readings with your device off the paper and comparing it to they profile's white point? If those are not matching up, how big if the difference, and what are the LAB values for the paper vs the profile.

[issa]

The White point certainly affects gamut since it represent the upper point of the gamut map. Depending on whether they created the profile using a spectrophotometer with a UV cut filter this could affect the white point's L* value by a little bit, but will certainly affect the a*/b* values, making the paper appear more blue or yellow, which will slightly alter the gamut, most noticeably if you ever use an absolute colorimetric rendering. It is also possible that they altered the white point, some manufacturers will do this, although it would be odd if they did.
When you say that you were not able to match the white point of their profile, are you just taking readings with your device off the paper and comparing it to they profile's white point? If those are not matching up, how big if the difference, and what are the LAB values for the paper vs the profile.

Hi Julian

Hahnemuhle reading
Lab: 99.73, 1.49, -3.8

My own reading using normal i1Pro no filter which I belive is what was used Hahnemuhle, this was clear from their spectral reading.
Lab: 96.54, 1.35, -3.90

You can see white point is nearly 100% pure white. The a &b are pretty close is the L value that very different

[Doombrain]

OBA Content = moderate. I would of thought any reading would of been done with a UV cut filter.

[Ernst Dinkla]

OBA Content = moderate. I would of thought any reading would of been done with a UV cut filter.

The spectral plot of HM Fine Art Baryta falls halfway between Fine Art Pearl and Photorag Bright White, the last has the lowest FBA content of the three. HM FAB has more FBA effect than many RC papers. I wouldn't call it moderate.

Issa,

My Eye 1 Basic Rev. D, without UV cut filter, on HM FAB with a non-FBA museum carton at the back, says Lab 97.4 1.4 -3.9
I doubt that 2-3 layers of FAB underneath (not an unusual method for profiling) will pull the whiteness that much higher. The FBA's that deep in the stack do not convert enough UV.
For L 99,75 you would need a high reflection over the entire spectrum, more like PTFE delivers. Of the papers I measured the highest was L 98.2.


met vriendelijke groeten, Ernst Dinkla

spectral plots of +100 inkjet papers:
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm

[Doombrain]

The spectral plot of HM Fine Art Baryta falls halfway between Fine Art Pearl and Photorag Bright White, the last has the lowest FBA content of the three. HM FAB has more FBA effect than many RC papers. I wouldn't call it moderate.

Take it up with HM. That info was taken from their tech data sheet for the media.

[issa]

Take it up with HM. That info was taken from their tech data sheet for the media.

Hi Doombrian

Agreea UV cut should have been used, but they have not, I analysed their profile, and they compensated for OBA in the profile making and used no UV filter. you can download their profile and check for yourself.

It looks it they have modified the white point or they used abatch of paper with high white reflectance.


I have measured the white paper and at best I get 97.7 1.3 -3.9

Here are the spectral data frof HFA profile and you can see that they did not use Non UV filter,  they used  TC 918 patch

Reference File  B25   255.00   255.00   255.00

SampleID   SAMPLE_NAME   nm380   nm390   nm400   nm410   nm420   nm430   nm440   nm450   nm460   nm470   nm480   nm490   nm500   nm510   nm520   nm530   nm540   nm550   nm560   nm570   nm580   nm590   nm600   nm610   nm620   nm630   nm640   nm650   nm660   nm670   nm680   nm690   nm700   nm710   nm720   nm730

59   B25   0.4618   0.5072   0.5900   0.7713   0.9827   1.0893   1.1084   1.0829   1.0552   1.0359   1.0206   1.0090   1.0013   0.9962   0.9937   0.9904   0.9890   0.9880   0.9847   0.9875   0.9872   0.9889   0.9902   0.9946   0.9995   1.0019   1.0051   1.0085   1.0109   1.0105   1.0103   1.0096   1.0102   1.0117   1.0112   1.0124

You will notice a reading of 1.1084 for nm430, to me that says 2 things, the papaer has reasonable mount of OBA and they did not use UV cut filter otherwise the reading would be much lower, also this is from their profile which confirms that they used OBA coorection in profiler.
taken from Pmtr in the profile tag table

Options = {
   GamutMappingMethod = "CIECAM02 GamutMapping"
   Copyright = "Copyright by LOGO GmbH, Steinfurt"
   CopyPerceptualToColRI = "1"
   CompensateFluorescence = "1"
}

[Ernst Dinkla]

Take it up with HM. That info was taken from their tech data sheet for the media.

I feel no urge to inform them. They sure know what their product is, that doesn't say they have to advertise that knowledge. The HM profile isn't representing the paper white either. A lazy reviewer could conclude that HM achieved a high whiteness and according gamut with "moderate" use of FBA.

Other spectral plots confirm my measurements:
http://www.pusztaiphoto.com/articles/print...s/webchart.aspx


met vriendelijke groeten, Ernst Dinkla

spectral plots of +100 inkjet papers:
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm

[MHMG]

Hi Julian

Hahnemuhle reading
Lab: 99.73, 1.49, -3.8

My own reading using normal i1Pro no filter which I belive is what was used Hahnemuhle, this was clear from their spectral reading.
Lab: 96.54, 1.35, -3.90

You can see white point is nearly 100% pure white. The a &b are pretty close is the L value that very different

Here are whitepoint readings of two more HN Fine Art Baryta samples, read with same Spectrolino, one sample from a batch of paper here at AaI&A, the other sample provided by an AaI&A member:

Sample #1 UV included:  L* = 97.6, a* = 1.4, b* = -3.7
                 UV excluded: L* = 97.3, a* = 0.1, b* = 0.8

Sample # 2 UV included:  L* = 97.4, a* = 1.5, b* = -4.1
                 UV excluded: L* = 97.3, a* = 0.2, b* = 0.5

HN's 99.73 reading seems almost certain to be an adjusted value.  Some profile builders like to tweak the profile predicted whitepoint to make the "simulate paper white" setting in Photoshop's softproof feature take less of a hit on monitor whitepoint brightness. That's the primary rationale I'm aware of for editing profile predicted whitepoints.

With UV inc/UVexc delta b* readings of 4.5 and 4.6 respectively for these two samples , I would say that "moderate" OBA is a fair statement (my personal cut-off for "moderate" versus "high" is delta b* = 5.0) That said, even though I wouldn't classify this paper as having high OBA content, it still exhibits significant OBA fade in under 20 megalux hours of exposure in my light fade tests. Other HN papers perform much better in terms of media whitepoint lightfastness.

On another note, there has been much general interest in data regarding initial media whitepoint, OBA levels, etc., for fine art papers on this and other forums.  I am in the process of upgrading the AaI&A testing database with Excel-like search and filtering features (it's about time as the list is starting to get long now  ). I have decided to rework the columns of data, adding several new ones that I believe will be helpful. Initial media whitepoint plus OBA levels, and UVinc/UVexc data will be added to all of the records as I collect all of this data at the beginning of my lightfade tests anyway.  I expect the revamped database will be ready to roll out in about two more weeks. Going through final programming debug and data entry right now.

cheers,
Mark
http://www.aardenburg-imaging.com

[issa]

Here are whitepoint readings of two more HN Fine Art Baryta samples, read with same Spectrolino, one sample from a batch of paper here at AaI&A, the other sample provided by an AaI&A member:

Sample #1 UV included:  L* = 97.6, a* = 1.4, b* = -3.7
                 UV excluded: L* = 97.3, a* = 0.1, b* = 0.8

Sample # 2 UV included:  L* = 97.4, a* = 1.5, b* = -4.1
                 UV excluded: L* = 97.3, a* = 0.2, b* = 0.5

HN's 99.73 reading seems almost certain to be an adjusted value.  Some profile builders like to tweak the profile predicted whitepoint to make the "simulate paper white" setting in Photoshop's softproof feature take less of a hit on monitor whitepoint brightness. That's the primary rationale I'm aware of for editing profile predicted whitepoints.

cheers,
Mark
http://www.aardenburg-imaging.com

Hi Mark

Your reading which are very close to mine, confirms that HN have tweaked the white point, not sure why? other than what you outlined, may be to avoid the shock when you switch sofft proof on, but does that also not enlarge the gamut. That last point I have very little experience with.

Thanks
Issa

[MHMG]

Hi Mark

Your reading which are very close to mine, confirms that HN have tweaked the white point, not sure why? other than what you outlined, may be to avoid the shock when you switch sofft proof on, but does that also not enlarge the gamut. That last point I have very little experience with.

Thanks
Issa

Well, maybe some other color management gurus should weigh in on this because I'm not fully versed on profile editing (I don't like to do it), but my understanding is that the media whitepoint adjustment is applied to the inverse transform table, meaning the table of data that photoshop uses to display the softproof, but the forward transform which controls the data getting sent to the printer can be left alone on this "fix". In that case the printer gamut isn't being messed with, and other software apps like Colorthink would presumably (but I don't know for sure) compute color gamut volumes and color mapping accuracy using the forward transform tables.  Of course, profile editing software can edit the forward transform, too, and then I would expect all bets are off as to how accurate any color mapping or gamut volume calculations would be using the edited profile's embedded tables.

cheers,
Mark