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Author Topic: z3100 used as a profiler for other printers  (Read 7988 times)
rdonson
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« Reply #20 on: April 27, 2007, 10:55:56 AM »
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Ron, I see your point. And I can certainly understand the temptation to get as much value out of the built-in spectro as possible by treating the HP as an automated patch reader, a vey big DTP if you will.
But in order to measure a profile target with the HP you have to associate it with either a new or current paper, which triggers, among other things ink limiting,  maximum density and linearity goals. Now if you choose a new/custom paper, the printer will have to output and measure a calibration target. Obviously this can't come from the desktop Epsons. So then you're measuring a profile target whose L numbers may be way way off what the measurment software expects. What would the ramifications be? How well does the on-board profiling software deal with large variations? Because this is in essence a closed profiling system, I don't know.
My instincts (and this is pure speculation) would say that since the HP system is designed around a calibration step which brings printer behavior into a pre-determined optimum state, that there must be a significant benefit as far as the profiling software goes, to receiving data points within a fairly reasonable tolerance range. Third-party profiling solutions are, on the other hand designed expressly for a wide range of inkjet printer models, in various states of performance. IMHO there are too many potential pitfalls  in using the on-board profiling software outside of the uses for which it was designed.
Overly cautious? Perhaps. But we've all got years of experience to remind us how tough it can be just to get products to do what they are advertised to do. So I try to keep my expectations for non-supported behavior to a mimumum  .
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Excellent points, Amadou.  Thanks for taking the time to explain.  Once again, there ain't no free lunch.  
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Regards,
Ron
Jim_H_WY
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« Reply #21 on: April 28, 2007, 06:45:15 AM »
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Ron, I see your point. And I can certainly understand the temptation to get as much value out of the built-in spectro as possible by treating the HP as an automated patch reader, a vey big DTP if you will.
But in order to measure a profile target with the HP you have to associate it with either a new or current paper, which triggers, among other things ink limiting,  maximum density and linearity goals. Now if you choose a new/custom paper, the printer will have to output and measure a calibration target. Obviously this can't come from the desktop Epsons. So then you're measuring a profile target whose L numbers may be way way off what the measurment software expects. What would the ramifications be? How well does the on-board profiling software deal with large variations? Because this is in essence a closed profiling system, I don't know.
My instincts (and this is pure speculation) would say that since the HP system is designed around a calibration step which brings printer behavior into a pre-determined optimum state, that there must be a significant benefit as far as the profiling software goes, to receiving data points within a fairly reasonable tolerance range. Third-party profiling solutions are, on the other hand designed expressly for a wide range of inkjet printer models, in various states of performance. IMHO there are too many potential pitfalls  in using the on-board profiling software outside of the uses for which it was designed.
Overly cautious? Perhaps. But we've all got years of experience to remind us how tough it can be just to get products to do what they are advertised to do. So I try to keep my expectations for non-supported behavior to a mimumum  .
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So with the APS, as it currently stands, you cannot simply use the HP printer's spectro to read a target printed by a different printer, and have the software (APS) generate an ICC profile that's independent of some paper and printer-characteristic assumptions being made based on the paper you've told it was used?

I'm being optimistic here, but...

What if you print targets on a 2nd printer.  Then you read those targets on the HP, lying to it and telling it that the paper is one of the ones that is already defined in its current repertoire.  That way, it doesn't need to print a new set of targets.

Ok, now it reads the existing target from the other printer.  Why would the APS need to make any assumptions about the paper characteristics (ink limit, etc.) just to read the targets and generate an ICC profile?  It seems to me that those characteristics would be applied when printing the target and not really be relevant when reading the target and generating the ICC profile.

That this profile would, indeed, be useless for the Z3100 would not matter because I'd use that profile with the other printer, printing on THAT printer using the same "paper type" as I'd used when I printed the targets.

Or am I missing some critical piece of the number-crunching that goes into reading a target and generating an ICC profile with APS?

I'm new to all of this and do not own any sort of spectrophotometer or profiling software.  So my understanding of this is incomplete.  A critical missing piece of my knowledge is:  Does a "normal" spectro/profiling system somehow let you enter the paper characteristics (ink limit, base paper tint, etc.) and then mix that data into things when coming up with the ICC profile?

I would have thought not.  It seems to me that the job of the profiling program would be to simply measure the patches and compare what it sees against what it expected to see, and thus create a calibration table which would tweak the colors in the file to be printed such that the errors in the printer/paper combination would be compensated.  And if that's the case, then it seems as though the APS along with the Z3100 could be fooled into creating an ICC profile which would work for a separate printer.

A previous post to this thread indicates that that poster has used the APS along with a Z printer to do just this.  And although they felt that it was no easier to do things this way than to use their other profiling system, there was no indication that the results were bad or faulty in some way.

Since I have no spectrophotometer or profiling program of any sort, it would add a great deal of value to the purchase of a Z3100 and APS if I could do this.  It would be my only way of generating profiles for my other printers in-house.   So you can see why I'd be interested.

Thanks for reading that long post.

Jim H.
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adiallo
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« Reply #22 on: April 28, 2007, 11:12:49 AM »
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Jim,
This is not an APS specific thread and my post was referring to the built-in non-APS calibration and profiling software. So I can't comment on the APS add-on.
Having said that, a printer profile can only do so much with regard to making a printer produce accurate color. A profile is simply a snapshot of a printer's behavior so that the number stat get sent to the printer can be altered behind the scenes to get a desired result. A calibration or linearization actually alters the output behavior of the printer to get closer to an ideal state of ink output. Calibration can take many forms. It's purpose is to allow the printer to perform at its optimum capability. It can be as simple as unclogging nozzles. It can be as complex as printing out and measuring 0-100% gradients from each ink channel.
All else being equal, a printer profile built on top of a calibrated or linearized printer will have less "heavy lifting" to do because the printer is in an optimal state before the profile target is printed. THis may result in the need for fewer patches in the profie target, for example. Early on, people complained about the relatively small number of profiling patches on the Z series printers. But in reality, the profiles created with this "small" patch count are pretty good. Certainly sufficient for a large majority of individual photographers. Perhaps HP can get away with a smaller patch count because the printer goes through a calibration routine before the profiling stage. Also, recent advances in printer drivers are leagues beyond earlier efforts with regard to linear behavior.
My main point in the earlier post is that the HP profiling software (non-APS) is designed to be used after the printer has been calibrated (ie brought to an optimum state of behavior). The decision of what and how many patches to include in a profiling target is as much art as science. And then there is the issue of how to interpolate the measured patches over the range of millions of discrete colors that we all want to print. So if the HP profiling system is designed to work with a calibrated printer, I question the benefit of extending this functionality to a wide variety of non-Z series inkjet printers which may be in widely different states of performance.
As you can see, many aspects of color management is still not as easy as the marketing hype would have us believe. Much better than a few years ago to be sure, but not transpaent by any means.
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Jim_H_WY
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« Reply #23 on: April 28, 2007, 01:41:06 PM »
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Hello, Amadou.

Thank you for your careful consideration of my questions.

You bring up some very good points.  The built-in linearization of the Z-Series printers is another of their great features.  Ideally, one could perform a linearization and then create a profile for a particular paper, and have very ideal results.  Later, periodic linearizations could assure that previously created profiles would continue to provide accurate results.

And as you point out, the relatively low number of patches used by the system may well be chosen and optimized to do exactly what needs to be done based on a known optimized state for this particular printer model with its particular inkset.  So despite people being dismayed by not seeing "enough" patches, the results my be every bit as good for this printer as a much higher number of patches might provide for a non-Z printer using a more "generic" profiling system which cannot make some of the assumptions that the APS (or the built-in Z profiling system) are able to make.  The interpolation algorithms, etc., may well be very optimized for this printer alone.

So there's no reason to believe that such a specialized and printer-optimized system would do a really great job of profiling a different printer.

But I feel that there should be nothing inherent in the Z-Series printers' spectrophotometer system that would prevent it from being used as a general purpose profiling solution as long as the software associated with it is written to support this functionality.

I suppose I should start a new thread discussing, in particular, the possibility of using APS (or another program) to provide this functionality.

But as has been pointed out elsewhere in this thread, it may be disappointing in the long run to have any hope that such additional functionality would ever be added to the APS.  It would add value to the HP printers, of course, but might overstep what X-Rite really wants this program to provide, and further, HP may feel that they have nothing to gain by allowing their printer to be used for profiling of other printers.

X-Rite would prefer to sell me a separate generic profiling system, and HP would want me to see their printer as being the only one to benefit from its built-in spectrophotometer.

But reading the first few posts to this thread, I, too, got the idea that the existing APS might do what I want.  But while it might turn out to be possible, I suppose the results may not be as good as what you'd get with a separate generic profiling solution which would not be making any assumptions about the target printer.

Thanks again for your time.

Jim H.
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Pigmenta
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« Reply #24 on: May 09, 2007, 04:02:17 AM »
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After spending more weeks to create profiles for other printers by Z3100, I have to say don't wait HP and X-Rite to update APS for profiling other printers but HP's. In the white pages of the new Z6100 they tell about the SDK (will be!) provided for third parties to include the built in spectro in RIP and CM softwares. I think APS will be the same for every Z-series printers. Just let wait some more time to have EFI, Onyx, and other RIP developers to include the Z-i1 spectro as measuring device.
APS and Z-i1 can measure the printed targets came with APS (different patches for RGB or CMYK process in TIF format). All previous CM options which determine the way the printer handles the actual media, HP assumes that already set up by the front panel of the printer. Selecting a media type on front panel of any HP LFP printers will setup the ink limiting, uni- or bidir printing, number of paths. The only thing you have to take care just select your media type always as you did when the patch was printed. The result is a calculated icc profile which can be saved to the system (win/system32/spool/drivers/color) and to the printer's hdd (as a backup). All icc profiles on the printer' hdd will be copied to the system updating the papers list by HP driver (Color Center).
I tried to create some profiles by EFI Colorproof XF 3.0. All basic measurements done by hand (i1) and the icc by Z-i1 using APS. The result icc was copied back to the RIP and combined with the basic media set (called epl in Colorproof XF). I compared the quality of the printouts with my previous profile (created by hand measurement) and with the Z-i1 profile. There are significant differences in light areas, the manual measuring was much more detailed in the color-range. This was not suprising me, the EFI target has much more patches than the APS TC9.18 cmyk target.

Tom
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