Profiling Printer with OCP Ink

stratman

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wcandrews@sccoast.net said:
Profiling OCP Ink

1. The OCP curing process improves the print. After curing, the gamut is greater, the whole intensity of the print improves, and the results are visible.

2. The objective of the profiling process is to get the best quality print from the particular ink/paper/printer combo.

3. If we make a profile with the profile test that has cured for three days, that profile will try to make a print that comes off the printer with the three day cure properties. That real print will then go through its own three day cure process and the result is a different print than expected.

4. The obvious workflow should be to make the profile very soon after the profile test print has been printed and before its curing cycle starts.
Number 4 does not make sense to me if number 1 is correct.

The image you use to profile should be the best possible one. Whether it's a store bought standardized target or the image the application requires you to print out as the target image, the idea is to profile on the most accurate image you can print with your printer and paper. If there is an actual difference in the image quality following a "curing" of drying for 3 days, then you use that 3 day cured image.

You use the best quality image available to get the best profile possible. If the image is "cured" in one minute or 10 days, ie no more color shifting, than that's the image that should be used.

Please explain more on your thought processes and results because intuitively it doesn't make sense to me.
 

l_d_allan

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pharmacist said:
Can someone do a gamut test?
I'm curious how one would do that.

Would the following be an approach:
* Print out patches with all the 0 & 255 combinations:
- 0, 0, 0
- 0, 0, 255
- 0, 255, 0
- 0, 255, 255
- 255, 0, 0
- 255, 0, 255
- 255, 255, 0
- 255, 255, 255

* Measure the patches with a spectro, and evaluate.

* Perhaps sum the variances, with lower being better?

* Use the same paper and compare to oem ink.

BTW, I'm one of the OCP ink users, but have no connection with R-Jet Tek. I do happen to like in the same city where they are located. It seems like good ink, but I haven't used any other non-oem, so I have no basis of comparison. Ounce for ounce, it does seem less expensive if you print enough to justify getting 16 oz at a time.
 

l_d_allan

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stratman said:
wcandrews@sccoast.net said:
4. The obvious workflow should be to make the profile very soon after the profile test print has been printed and before its curing cycle starts.
Number 4 does not make sense to me if number 1 is correct.
I think wcandrews is correct, although it does seem counter-intuitive. By using the "3 day cured print" for the profile target, you could get the equivalent of "double profiling" where both the application and the printer are managing color.

It does make me wonder if this influences the quality when you have profile made by a distant vendor, and send them your print via snail-mail. That takes several days.
 

wcandrews@sccoast.net

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Pharmacist wrote:
Can someone tell me why all this fuzz about OCP ink is good for ? Why not a same story about Hobbicolors or Image Specialists. One could make a very similar story about curing, profiling and tips about other refill inks. I hope this is not another form of this time organized spam attempt using several "members" creating an artificial hype over OCP ink, having several new members who surprisingly all seems to mention OCP in one way or another in their posts. Am I the only one who has noticed the suddenly rise of OCP posters on the nifty-stuff forum ???

Maybe I'm getting paranoia...

Can someone do a gamut test, fading test of several types of refill inks: Image Specialists, Hobbicolors UW-8, Inktec CLI-8, OCP for the 4 dye colours: cyan, magenta, yellow and photo black on one type of standard microporous paper and then report back. I am willing to redo the tests, if someone is willing to provide the ink to me, so I can recheck the fading tests.
Im sorry if sharing my work and conclusions offended you. I only talk about what I have actually tested. The only ink I have to test is OCP. If sharing this work with the forum is a problem, Ill make this my last posting.

Good Luck,
Wil
 

on30trainman

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Wil,
Don't stop posting. I switched to OCP ink a few months ago and I am a "fan". No one can accuse me of being a OCP spammer since I have been on this forum for many years and have used Canon OEM, Hobbicolors and Image Specialists inks besides OCP. I plan to do my non-scientific fading test later in the year when the sunshine is longer and more intense. Pharmacist should easily be able to obtain OCP ink since it comes from Germany but the minimum quantities from there may be large as we have to buy here in the US.

Steve W.
 

RogerB

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wcandrews@sccoast.net said:
Im sorry if sharing my work and conclusions offended you. I only talk about what I have actually tested. The only ink I have to test is OCP. If sharing this work with the forum is a problem, Ill make this my last posting.

Good Luck,
Wil
Hi Wil,

I'm sure nobody on the forum objects to you sharing your experience. For me, the only problem is that your conclusions are based on your visual assessment of certain prints - one looks "better" than another. Being entirely subjective, this is not an easy thing to share with other members. If you are talking about a change in colour gamut or other rendering properies, then some objective assessments would be appreciated.

Comparisons of colour profiles are not difficult, given the appropriate software, and I am sure that such objective comparisons would be of interest to the forum members. If you are unable to do such comparisons yourself I am sure there are other forum participators (including me) that would be happy to do them, for everyone's benefit.

Incidentally, without wishng to dampen everyone's enthusiasm about OCP inks and the Pro 9000 in general, the Aardenberg Imaging data for this printer, using OEM (dye) ink and microporus paper, does not give a good longevity rating. Typically it's 10x worse than the worst printer/ink/paper combinations using pigment ink. Results are much better using a swellable coating paper (Ilford Classic), but this type of paper is becoming more and more difficult to obtain.

Before anyone protests about longevity, I know that there are millions of prints on people's walls/fridges/desks from dye-ink printers that are still "as good as new". If you are among the people that have these prints then forget about "longevity". The academic requirements for "archival" prints are much more stringent than the average user's requirements. But don't expect any prints from the Pro 9000, with OEM or OCP ink, to be unchanged in 30 years time.
 

stratman

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Thinking more on profiling an "uncured" target image...

If you profile using the cured image then the resultant profile will instruct for prints that resemble fully cured images straight from the printer that then themselves cure. This would effect a "double-curing" on the final image and the final dry and cured image will appear different.

The idea then is to use a target image that is dry to prevent smearing when scanning and to profile this dry target image ASAP in the curing process as this will resemble closest to what the printer is capable of (its limitations) and not the additive effects of time on ink and paper resulting from the curing process.

I'm trying to see the process here and still not sure I buy it yet. What do the spectrophotometer instructions say?
 

martin0reg

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A simple comparison would help:
- canon ink on canon paper and on a good third party paper
- ocp ink on same canon paper and on the same third party paper
- IS or hobbicolors or whatever ink on the same sort of paper

Put the prints on a scanner, scan all prints with the same settings and let us see.

Quality depends on the combination of printer-paper-ink.
"Wider gamut" may be hard to distinguish from greater intensity or saturation...
 

RogerB

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stratman said:
Thinking more on profiling an "uncured" target image...

If you profile using the cured image then the resultant profile will instruct for prints that resemble fully cured images straight from the printer that then themselves cure. This would effect a "double-curing" on the final image and the final dry and cured image will appear different.
The profile will simply use the measurement of the target to determine how the printer reproduces colour. If you measure the target within minutes of printing it, subsequent prints using the profile should look "correct" within minutes of printing. If they change with time, then they will no longer be correct.

The profiling process assumes that the target measurements are representative of the final print properties. Any intermediate stages are irrelevant. The profiling software has no idea what the printed target looks like straight from the printer. You should not use measurements of transient conditions for generating profiles.

Take the extreme case of sublimation printing. The printer deposits ink onto a sheet of transfer paper. The paper is then heated in contact with the final substrate; the ink sublimes and is taken up by the substrate. The finished substrate is what has to be measured for a profile. The appearance of the image on the transfer paper is transient and irrelevant. The profile has to be based on the end-to-end process, even if the ends are just time between leaving the printer and reaching a stable condition.
 

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Every guide I've ever seen said that it is best to have a fully dry profile target, which makes the most sense to me.

By profiling before the target is really dry you may get colors that are more "pleasing" to your eye, but I can't see how they could possibly be more accurate.
 
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