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Author Topic: Finally a good B&W metal print without a profile!  (Read 2980 times)

dgberg

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Finally a good B&W metal print without a profile!
« on: May 19, 2020, 08:53:43 am »

Took several hundred dollars worth of metal, paper and ink and after all that I got a good B&W print  from Managed By Printer
I built more than several grayscale profiles and everyone had a strong greenish colorcast. I know I spent 40 hours working on this.
So yesterday I decided to print the same file with Managed by printer. Guess what it was black and white with no colorcast. Too dark in the shadows but I can fix that.
With +.50 exposure, +75 shadows and +5 added in printer brightness it was darn near perfect.
How could that be that a i1 Pro2 grayscale profile would have an ugly colorcast and a Managed By Printer was almost perfect?
Guess I should have tried it right from the start. They call color management a science, I call it a pain in the arse!

The 8x10 (Still a little dark) is the Managed By Printer and the 4x4 my icc grayscale profile with greenish sky.
« Last Edit: May 19, 2020, 12:07:43 pm by dgberg »
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aaronchan

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Re: Finally a good B&W metal print without a profile!
« Reply #1 on: May 20, 2020, 03:20:56 pm »

What process are we talking about here?

digitaldog

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Re: Finally a good B&W metal print without a profile!
« Reply #2 on: May 20, 2020, 05:00:03 pm »

When I hear somebody say, 'color management is hard' I am always tempted to ask, 'Compared to what?'
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kers

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Re: Finally a good B&W metal print without a profile!
« Reply #3 on: May 20, 2020, 06:16:08 pm »

could it be measuring metal like sufaces with an x-rite device does not work very well?
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dgberg

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Re: Finally a good B&W metal print without a profile!
« Reply #4 on: May 20, 2020, 08:24:42 pm »

What process are we talking about here?
Dye sublimation for metal prints.

dgberg

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Re: Finally a good B&W metal print without a profile!
« Reply #5 on: May 20, 2020, 08:26:25 pm »

When I hear somebody say, 'color management is hard' I am always tempted to ask, 'Compared to what?'
Oh just venting because I spent so much time with unsatisfactory results.

dgberg

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Re: Finally a good B&W metal print without a profile!
« Reply #6 on: May 20, 2020, 08:36:25 pm »

could it be measuring metal like sufaces with an x-rite device does not work very well?
I don't think that is the issue.I made a real good color profile for my chromaluxe metals, same substrate.
Issue seems to be when sublimating grays. Deep blacks are good. The grays are what gets the green colorcast. I could possibly have a good profile and just a sight change in time, temperature and pressure and grays get a green colorcast. I have been told the only way to get this right is with a rip. Might be cheaper to stop doing b&w metals then pay for an expensive rip? At least what I have now is sellable, not perferr but pretty decent.
« Last Edit: May 20, 2020, 11:59:34 pm by dgberg »
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Ferp

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Re: Finally a good B&W metal print without a profile!
« Reply #7 on: May 22, 2020, 12:23:17 am »

First, congratulations on finally getting a good (neutral) print.

How could that be that a i1 Pro2 grayscale profile would have an ugly colorcast and a Managed By Printer was almost perfect?

The view that I eventually came to in that other thread on this topic was that neither a QTR grayscale curve nor a QTR grayscale ICC in and of themselves were going to solve the problem.  They weren't going to correct for an inherent color bias in your printing pipeline simply by being grayscale.  It may if you tweak the small amount of toning inks that a QTR curve uses to achieve neutrality specifically for your media.  But as I said, that is a rare skill.  I thought that Richard Boutwell was going to help you do that - did anything come of it?

I guess I'm surprised that Printer Manages Colors gave you a neutral result.  This reminds of an instance several years ago over on The Online Photographer blog when C'tein argued for printer Manages Colors, based on an image where a deep blue came out wrong using a color managed workflow, but right using Printer Manages Colors.  MHMG analysed the image and found that the blue in question was just one of those colors that are at the boundaries of what CM can deal with.  My recollection is that Mark argued that C'tein just got lucky with that image, or perhaps just got unlucky in that it didn't suit a CM workflow.  My hunch is that your case is similar.  I suspect you got lucky.  If it were me, I'd count my blessings and run with it. 
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PeterAit

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Re: Finally a good B&W metal print without a profile!
« Reply #8 on: May 22, 2020, 11:41:26 am »

I am far from an expert in this, but it seems to me that there would be a way to tell the printer to use just the B&W inks, thus removing any chance of a color cast. No?
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digitaldog

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Re: Finally a good B&W metal print without a profile!
« Reply #9 on: May 22, 2020, 12:04:51 pm »

I am far from an expert in this, but it seems to me that there would be a way to tell the printer to use just the B&W inks, thus removing any chance of a color cast. No?
No. That's not at all how Epson as an example creates (can create) dead nuts neutral B&W thought it's Advanced B&W option.
As for Printer Manages Color, it's far, far from ideal as outlined in the Online Photo comments.
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dgberg

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Re: Finally a good B&W metal print without a profile!
« Reply #10 on: May 22, 2020, 12:55:13 pm »

The Wasatch rip can remove the other inks but the colorcast comes from pressing not from printing. I think I have a good profile but when pressing the colorcast pops up.
 I am getting closer but if I don't get it right it will be easier to stop selling black and white metals.
Most of the colorcast comes out when pressing with 400 degree heat.
You can get black, green, brown, magenta when pressing blacks and grays, it really is difficult to nail down.
« Last Edit: May 22, 2020, 01:00:52 pm by dgberg »
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Lessbones

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Re: Finally a good B&W metal print without a profile!
« Reply #11 on: May 24, 2020, 03:54:43 pm »

It's not a color shift at all, it's a matter of perception.

When profiling dye-sub on chromaluxe I regularly get profiles that read as having a L* minimum value as "0" which, afaik, shouldn't be possible except in a black hole.  One problem is that we are dealing with dyes here, not pigments, so there is no way to get an actual neutral black-- it's simply a combination of colors in a fragile balance, which are INCREDIBLY affected by the spectra of the viewing light.  If you measure the darkest black values in a profiling chart on chromaluxe with a spectro, even though it may visually look "neutral," it will measure with a huge amount of energy in the near-infrared part of the spectrum.  The brighter the light you shine on the patch, the more red you'll see in it--  This is seen by the spectro, which compensates for it by adding green (cyan, really).

I've done experiments with trying to measure through an IR filter, which was interesting, but not very practical, as it severely reduced the amount of light input and made the readings really unstable.  Additionally, I've used custom lighting measurement spectra within i1profiler to simply devalue the importance of the deep red end of the spectrum-- either by simply zeroing out values in the text file for the lighting measurement, or by measuring a custom light source with very little energy in that end of the spectrum (like some LEDs).

But so far the best method I've found is by using basiccolor IMprove or ColorLogic ColorANT to change the measured spectrum of the "K" value to something that was measured from a pigment ink in another ICC profile.  This sounds ridiculously convoluted, I know, but it does work.  Since I'm not working towards any kind of proofing standard, the perceptual neutrality that results from this method is the endgame.

essentially what kers said is not far off the mark-- measuring with an x-rite device simply isn't quite adequate.  But this applies to all other spectros as well (i've tried barbieri also).  Essentially as I can define it myself, the problem stems from the fact that our human visual system stops seeing color at a certain lightness value, and we begin to perceive the grey axis as neutral once it dips below a certain threshold, whereas the spectro continues to see this as very red.  Additionally, the more light present in the room, the redder the image will appear to the human eye--   I know of no other printing process that changes color based on the AMOUNT of light present, and I also know of no color management system which is capable of taking this into account.  Ideally it seems like this would be most closely solve-able via improvements to the custom lighting measurement part of profiling software, things can already be affected by the amount of energy in a given part of the spectrum.

This is all in addition to the fact that the temperature/pressure/time of the transfer process can greatly affect the color--  I find that it is incredibly easy to "toast" the surface of the chromaluxe by leaving it in for a little too long (or even letting it sit under the heated platen after pressing time expires for too long) which further compounds the incredible difficulty of getting repeatable results.

When transferring to polyester fabric, the process behaves much more like you'd expect it to in any other print process-- so the powder coat on the metal plays a significant part in the equation.  It may be completely different for any other manufacturers, but for chromaluxe, these are my general findings--

-Cody
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dgberg

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Re: Finally a good B&W metal print without a profile!
« Reply #12 on: May 25, 2020, 08:01:44 am »

Thank you Cody, a very good read.
Explains a little more in depth why I feel like a cat chasing it's tail. Especially with my limited knowledge profiling, Chromaluxe in particular.

Alistair

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Re: Finally a good B&W metal print without a profile!
« Reply #13 on: July 30, 2020, 08:14:55 pm »

I feel your pain! It looks like the Managed By Printer approach is only using your K and grey dyes whereas the profile is firing in some colour to overcome the red seen by your spectro in the k. What does the spectral curve look like for the blacks in the Managed By Printer print?

In our shop we use two general approaches to reproducing greys and blacks. Firstly do a separation for the true black and print it as a spot colour using a black formula you know works. This of course requires you have an accurate registration system and a way to make the separations.

In addition to or instead of the above approach we will tweak the print environment to define the black point and the grey gradient. I do not recall what RIP you use but a RIP designed to be used for sublimation will support this. It is done after the profile is made and will allow you to replace the black point with your own formula and will also provide a grey optimiser tool of some sort to tweak a grey gradient to achieve the tones you want.

As an aside, IMO this image is not an ideal candidate for Chromaluxe. Any chance the customer be talked into a nice framed pigment print on German Etching behind Museum glass!!?
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