Luminous Landscape Forum
Raw & Post Processing, Printing => Colour Management => Topic started by: Doug Gray on July 18, 2019, 08:10:27 pm
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I've been looking closely at the different quality of profiles generated by an assortment of paper with my different printers. To establish base accuracy, I have a special set of 125 RGB values going in steps of 64 from 0,0,0 to 255 as well as a set of device neutrals from 0,0,0; 16,16,16... 255,255,255. These sets are duplicated 6 times, randomized, and printed on a single US letter. Scans are then de-randomized and the two sets are averaged. There is a fairly consistent average dE00 between the same color patches of .20 on all the papers. Averaging the 6, same color patches reduces the variation. Scans of these averages match quite closely the first day (match within about .08 dE00) then gradually diverge.
On high OBA papers like Canon MP101, Epson Ultra Premium Glossy, and Costco Glossy there is about a 1 to 1.3 dE00 shift after a month. OTOH, the divergence is only about .15 dE00 on Canson Rag Photo matte which has zero OBA and a non fluorescent base. and about .3 on papers like Finestra Barya SG. or Epson Prem. SG. which has a slightly fluorescent base.
It would seen that high OBA paper produces significant shifts in a relatively short time. At least with the Pro1000. Drying time is close to irrelevant. All the papers reach stability under .1 dE within an hour of printing but the high OBA papers show a slow drift for over the next month. Perhaps this isn't unexpected since the difference in white points for the high OBA papers is about dE13 between M2 and M1 but all of the above measurements were done with M2 so fluorescence shouldn't be a factor. Possibly the OBA is deteriorating or somehow interacts with the ink.
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Thanks!
It's good to have concrete evidence like this.
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Possibly the OBA is deteriorating or somehow interacts with the ink.
Or the ink drying time increases because the carrier fluids aren't absorbed as easily?
OTOH the OBA might reflect (and produce) more UV then in non OBA cases, which could potentially influence ink makeup.
Did you measure the paperwhite itself over that same time? How was it affected?
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Did you measure the paperwhite itself over that same time? How was it affected?
I believe there is data on this in the Aardenburg database. We know that high OBA papers eventually yellow and that can be fairly quick for some papers. IIRC, Epson had a matte paper with high OBA content that would turn within a month or two.