Luminous Landscape Forum
Raw & Post Processing, Printing => Printing: Printers, Papers and Inks => Topic started by: Clark on July 09, 2018, 02:32:20 pm
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Hi all, I have just tried a test print using Absolute Colorimetric as the rendering intent for a print.
I noticed that the print head was running back and forth far more than I expected.
On closer inspection I realised that it has printed a pale yellow, off-white colour across the entire paper (all white space). At first I suspected some sort of human-error (an unwanted adjustment layer in the document or maybe background of the image filled with some colour other than white), but I have tested again, and it is definitely the Absolute Colorimetric setting that is doing it.
When printing the same image with relative colorimetric intent, the print head only passes over the image area as expected, and the white border areas are fed through the printer with no head passes.
Can anyone explain this? I have no idea what's going on here.
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Quote JP Caponigro
Absolute Colorimetric
"An absolute colorimetric rendering intent differs from relative colorimetric because it doesn’t map the source white to the destination white. It reproduces hues absolutely. If the source is a clean white reproduced on yellow paper the result will be a yellow white. If the source is a cool white reproduced on a warmer paper, cyan ink will be used to simulate the cool white of the source. Th absolute colorimetric rendering intent is intended for cross-rendering simulations of output condition with another."
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Depending on the paper, the paper profile and how it is interpreting "paper white", this is not unusual when printing with Absolute Rendering Intent, which does not scale colour to the destination white point. It can be particularly noticeable if the paper has OBAs that the profile may be "over-correcting" for, by over-extinguishing the blue with yellow. Normally, the only reason to use Absolute Rendering Intent is for proofing.
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On closer inspection I realised that it has printed a pale yellow, off-white colour across the entire paper (all white space).
Exactly to be expected and WHY you don't use such a rendering intent unless your goal is to simulate the paper white of another process. Absolute and Relative Colorimetric share the same profile table and expect for this handling of white, do not differ whatsoever. So you probably don't want to be using Absolute. FWIW, you should also see this paper and white effect soft proofing.
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Interesting, and thanks for the info all. 8)
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Nice. I learned something here.
Sent from my iPhone using Tapatalk
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Exactly to be expected and WHY you don't use such a rendering intent unless your goal is to simulate the paper white of another process. Absolute and Relative Colorimetric share the same profile table and expect for this handling of white, do not differ whatsoever. So you probably don't want to be using Absolute. FWIW, you should also see this paper and white effect soft proofing.
They share the same table but alter much more than the handling of white. They try to replicate, colorimetrically, the image's colors without change. Rel. Col. shifts everything, not just the paper white, to align L*a*b* 100,0,0 with paper white and alter other colors accordingly. This results in a general decrease in printed luminance for in gamut colors. For instance, if a paper's unprinted white point is L*a*b* 95, -1, -2, a fairly typical glossy white, a L*a*b* value of 80,0, when printed using Relative Colorimetric, will be measured with a spectrophotometer around 76, -1,-2. But when printed in Absolute Colorimetric it will measure as close to 80,0,0 as it's profile's accuracy permits.
When asked to print a color that is out of gamut, and "white" is since papers aren't pure white (100% reflective across the spectrum), the profile will provide a close proximity to that color, usually what is closest as determined by Delta E 1976's metric. Since most papers have a slightly bluish hue, a small amount of yellow ink is added which shifts the b* from a negative value towards 0. Hence the slightly warmer color than the unprinted paper. Since yellow has almost no impact on L* compared to its strongly positive b* shift, this results in a smaller Delta E and is why the print appears warmer.
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Depending on the paper, the paper profile and how it is interpreting "paper white", this is not unusual when printing with Absolute Rendering Intent, which does not scale colour to the destination white point. It can be particularly noticeable if the paper has OBAs that the profile may be "over-correcting" for, by over-extinguishing the blue with yellow. Normally, the only reason to use Absolute Rendering Intent is for proofing.
This is a very good point. The amount of shift towards yellow is far greater for papers with high OBAs where the profile was created using M0 or M1 which includes uV. Quite different from Rel. Col. or Perceptual where mapping is always to paper white regardless of the shift from OBAs. Consequently, high OBA papers will see the most shift towards yellow with high OBA papers and profiles made with M0 or M1 when Absolute Colorimetric printing is used while there is little difference with Relative or Perceptual Intent.
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Yes indeed, high OBAs can be counted on to produce this effect with Abscol when profiling to M0 or M1, but not so for M2 which is equivalent to UV Cut. So for whatever reason anyone wants to work in Absolute R.I., they would be advised to make and use M2 profiles if they wish to not see a yellow tint in their prints. The better options for most intents and purposes are to either not use heavily OBA-laden paper (a good idea regardless of R.I.) or use RelCol or Perceptual R.I. to taste.
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Yes indeed, high OBAs can be counted on to produce this effect with Abscol when profiling to M0 or M1, but not so for M2 which is equivalent to UV Cut. So for whatever reason anyone wants to work in Absolute R.I., they would be advised to make and use M2 profiles if they wish to not see a yellow tint in their prints. The better options for most intents and purposes are to either not use heavily OBA-laden paper (a good idea regardless of R.I.) or use RelCol or Perceptual R.I. to taste.
Yep. Rarely any reason to use AbsCol. I use it when doing reproductions where I'm trying to match the original's colors. Especially in the highlight areas. Also when making color patches to match paint around the house :) OBA free is required for both.
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Nice. I learned something here. . . .
Me, too! Interesting discussion.
Rand