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Author Topic: QuadToneRIP QTR - Unexpected Color Tint  (Read 3122 times)

Jasper

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QuadToneRIP QTR - Unexpected Color Tint
« on: March 21, 2018, 11:07:25 AM »

Just tried printing my first B+W image using QTR and there is a clear green tint  :(

The file I printed was created in Photoshop and saved as 16-bit, Gray Gamma 2.2, TIFF, No compression, Interleaved pixel order, IBM PC byte order.  Image prints neutral from Photoshop/Epson ABW (obviously).

I'm printing directly from QTR (Windows 10) using a user-created curve per the attached screenshots.  Curve Creater tabs not shown in the attachment are left blank (Toner Curve, Toner 2 Curve and Notes).

As I have only selected three Inks (K, LK, LLK), all defined as Gray, I would have thought it was impossible to print with a tint, regardless of other settings (assuming Epson Inks are neutral)?

Any ideas why there is a tint to the image?  Are Epson's K, LK, LLK Inks neutral or not?
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smthopr

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Re: QuadToneRIP QTR - Unexpected Color Tint
« Reply #1 on: March 21, 2018, 12:17:24 PM »

Just tried printing my first B+W image using QTR and there is a clear green tint  :(

The file I printed was created in Photoshop and saved as 16-bit, Gray Gamma 2.2, TIFF, No compression, Interleaved pixel order, IBM PC byte order.  Image prints neutral from Photoshop/Epson ABW (obviously).

I'm printing directly from QTR (Windows 10) using a user-created curve per the attached screenshots.  Curve Creater tabs not shown in the attachment are left blank (Toner Curve, Toner 2 Curve and Notes).

As I have only selected three Inks (K, LK, LLK), all defined as Gray, I would have thought it was impossible to print with a tint, regardless of other settings (assuming Epson Inks are neutral)?

Any ideas why there is a tint to the image?  Are Epson's K, LK, LLK Inks neutral or not?
I think if the inks were really neutral, then the ABW driver would not need to mix in color inks, but it does.  Why not stick with the ABW driver and create a correction profile with QTR?
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Jasper

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Re: QuadToneRIP QTR - Unexpected Color Tint
« Reply #2 on: March 21, 2018, 12:47:59 PM »

Smthopr - I don't want to turn this into a ABW versus QTR thread.  I'm trying to find out why a QTR print has a clear color cast. BTW, just because a printer uses color inks in a B+W mode does not mean the gray inks are not neutral.

I had assumed that Epson's K, LK, LLK inks were neutral.  I just need someone that has used QTR with these three Epson inks to confirm (BTW the Printer is P600) and anyone more familior with QTR than I to point me in the right direction.

Thanks.
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digitaldog

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Re: QuadToneRIP QTR - Unexpected Color Tint
« Reply #3 on: March 21, 2018, 01:04:12 PM »

Smthopr - I don't want to turn this into a ABW versus QTR thread.  I'm trying to find out why a QTR print has a clear color cast. BTW, just because a printer uses color inks in a B+W mode does not mean the gray inks are not neutral.

I had assumed that Epson's K, LK, LLK inks were neutral.  I just need someone that has used QTR with these three Epson inks to confirm (BTW the Printer is P600) and anyone more familior with QTR than I to point me in the right direction.
Less to do with inks being 'neutral' and how each is mixed! The issue could be metameric failure. Do you see this color cast no matter what light source you view the prints under?
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Andrew Rodney
Author “Color Management for Photographers"

Jasper

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Re: QuadToneRIP QTR - Unexpected Color Tint
« Reply #4 on: March 21, 2018, 01:13:19 PM »

Less to do with inks being 'neutral' and how each is mixed! The issue could be metameric failure. Do you see this color cast no matter what light source you view the prints under?

This isn’t Metamerism. I don’t know what you mean by it not being about whether the inks are neutral. As I am only using 3 inks I think if they are not neutral I won’t have a neutral image.
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digitaldog

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Re: QuadToneRIP QTR - Unexpected Color Tint
« Reply #5 on: March 21, 2018, 01:42:24 PM »

This isn’t Metamerism.
IF you understand what Metamerism is, it absolutely isn't that! It may be metameric failure which is totally different. And if you answer the question about how you're viewing the print, we can conclude if this is the case or not.
Do you want to know what Metamerism is? Because we absolutely desire this phenomena!
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Andrew Rodney
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Jasper

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Re: QuadToneRIP QTR - Unexpected Color Tint
« Reply #6 on: March 21, 2018, 02:05:21 PM »

Hi Andrew, I understand what metamerism is and to answer your question, it does not matter what light I view the print(s) under - they have a clear, visible, constant color cast.  However, I want to keep this thread on track...

I'm trying to find out from those that have used Epson K3 inks in QTR whether they are neutral (specifically for P600 / UltraChrome HD inks).  Obviously with a 3 ink set up, the printer should only be using 1 or 2 inks for a given tone.  So based on what I see, It appears that the K, LK and LLK inks are not neutral. 

However, I do not know exactly what the QTR driver is actually doing.  I assume it is asking the printer to use only these three inks, as that is how I set QTR up, but I am not familiar with QTR so perhaps I made a mistake.
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aaronchan

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Re: QuadToneRIP QTR - Unexpected Color Tint
« Reply #7 on: March 21, 2018, 02:18:01 PM »

Epson K3 inks are not even near natural at all!




Sent from my iPhone using Tapatalk

digitaldog

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Re: QuadToneRIP QTR - Unexpected Color Tint
« Reply #8 on: March 21, 2018, 02:20:52 PM »

Epson K3 inks are not even near natural at all

Sent from my iPhone using Tapatalk
Fortunately it doesn’t matter as dead nuts neutral prints are possible. With Epson’s Advanced B&W driver as already mentioned.
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Andrew Rodney
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Jasper

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Re: QuadToneRIP QTR - Unexpected Color Tint
« Reply #9 on: March 21, 2018, 02:27:04 PM »

Epson K3 inks are not even near natural at all!

Thanks Aaron, that's what I wanted to know - at least it confirms I'm not doing anything wrong!
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Stephen Ray

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Re: QuadToneRIP QTR - Unexpected Color Tint
« Reply #10 on: March 22, 2018, 11:23:41 AM »

Just tried printing my first B+W image using QTR and there is a clear green tint  :( Any ideas why there is a tint to the image?  Are Epson's K, LK, LLK Inks neutral or not?

Can you closely inspect the printed dots with a loupe and tell us what you find? Maybe create some sort of test file with gray swatches using both QTR and ABW?
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Jasper

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Re: QuadToneRIP QTR - Unexpected Color Tint
« Reply #11 on: March 22, 2018, 01:35:29 PM »

Can you closely inspect the printed dots with a loupe and tell us what you find? Maybe create some sort of test file with gray swatches using both QTR and ABW?

Hi Stephen - Aaron confirmed why this is in his post above. The Epson black/grey inks have a significant tint (quite strongly green).

Regards
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digitaldog

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Re: QuadToneRIP QTR - Unexpected Color Tint
« Reply #12 on: March 22, 2018, 02:03:41 PM »

Hi Stephen - Aaron confirmed why this is in his post above. The Epson black/grey inks have a significant tint (quite strongly green).
Sigh.... That ignores the FACTS that neutral prints using Epson inks CAN and DO produce neutral output.
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Andrew Rodney
Author “Color Management for Photographers"

Jasper

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Re: QuadToneRIP QTR - Unexpected Color Tint
« Reply #13 on: March 22, 2018, 03:05:03 PM »

Sigh.... That ignores the FACTS that neutral prints using Epson inks CAN and DO produce neutral output.

Andrew, I think you’re the one ignoring facts. Read the OP. I clearly state that AWB produces neutral prints. And I clearly state the tint is when using 3K QTR.
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digitaldog

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Re: QuadToneRIP QTR - Unexpected Color Tint
« Reply #14 on: March 22, 2018, 03:38:01 PM »

Andrew, I think you’re the one ignoring facts. Read the OP. I clearly state that AWB produces neutral prints. And I clearly state the tint is when using 3K QTR.
He (you) and I are correct and hence, the idea some inks are not neutral is moot! So yeah, you're doing something wrong as you outlined in post on: March 21, 2018, 02:27:04 PM.

« Last Edit: March 22, 2018, 03:43:25 PM by andrewrodney »
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Andrew Rodney
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Jasper

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Re: QuadToneRIP QTR - Unexpected Color Tint
« Reply #15 on: March 22, 2018, 04:44:21 PM »

He (you) and I are correct and hence, the idea some inks are not neutral is moot! So yeah, you're doing something wrong as you outlined in post on: March 21, 2018, 02:27:04 PM.

Andrew, I think you have misunderstood this post.  I'm not sure how familiar you are with QTR, but I'll explain the point of my query...
  • QTR is a "RIP" for printing B+W, which many people use in lieu of Epson driver/ABW.
  • I am trying out QTR, using Epson's 3K inks initially, to see if it offers potential improvement over AWB.  If it looks promising, I will switch to piezography inks (these are inks produced by a third party which potentially provide superior B+W results to stock Epson inks).
  • I created a linearized profile/curve for these inks and the paper I am using.
  • When printing with this combination, I found there was a significant green bias.
  • There are three obvious possible reasons for this (sorry for not including metameric failure as a potential reason :) ) - (i) the ink-set is not neutral (ii) I set up the profile/driver incorrectly (iii) QTR is doing something unexpectedly
  • I suspected the inkset, hence this post to find out if the inkset is neutral

Aaron confirmed this in reply #7, closing my query - i.e. the reason for the tint is because the inks are not neutral, not because I was doing anything incorrectly. 

So knowing this, I know my methods and workflow is good.  Other than the tint, which will obviously be addressed when I move to the piezography inks, the print looks very good (better) compared to the 'stock' Epson ABW prints.

Hope that gives you a better insight to this query.

Regards

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digitaldog

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Re: QuadToneRIP QTR - Unexpected Color Tint
« Reply #16 on: March 22, 2018, 04:46:40 PM »


So knowing this, I know my methods and workflow is good.  Other than the tint, which will obviously be addressed when I move to the piezography inks, the print looks very good compared to the 'stock' Epson ABW prints.

Hope that gives you a better insight to this query.

Regards
Then you're set and we're all done here.
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Andrew Rodney
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Stephen Ray

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Re: QuadToneRIP QTR - Unexpected Color Tint
« Reply #17 on: March 22, 2018, 05:26:31 PM »

<snip> Other than the tint, which will obviously be addressed when I move to the piezography inks, <snip>

How you do know those inks will be neutral?
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Jasper

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Re: QuadToneRIP QTR - Unexpected Color Tint
« Reply #18 on: March 22, 2018, 05:49:34 PM »

Stephen,

There is a choice of Piezography inks to produce neutral or toned prints.  If you are interested in them and want neutral prints they have an inkset which is (quoting them) "designed to be achromatic to the human visual system when printed on a very specific color of white paper: Hahnemuhle Photo Rag. When viewed under full spectrum 5000k a photograph on this paper will appear to be neutral".  Obviously, if one uses a warmer (or colder) paper, the prints will be warmer (or colder) too.

I haven't decided which inkset I'll go with yet, but I certainly won't be going green  :)
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Ferp

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Re: QuadToneRIP QTR - Unexpected Color Tint
« Reply #19 on: March 22, 2018, 07:55:26 PM »

I agree with others that the three Epson black inks are not neutral.  I'd have said warm rather than green, but it may depend on which generation Epson inkset you're using.  You can see this by examining the "warm" curves that ship with QTR which use only the thee black inks without any colors added for toning effect.

Both ABW and QTR have to add in small amounts of the color inks to achieve a neutral print.  Unlike Mr Rodney, in my experience neither of them is particularly successful.  I find ABW prints at the neutral setting to be a bit cooler than neutral, and for this reason I can usually spot a "neutral" ABW print in an exhibition.  QTR neutral is a bit warmer than neutral.

You can tweak both approaches to achieve a more neutral print.  It's easier to do this in ABW because there is a color toning wheel in advanced color settings, but it's still trial and error process as the on-screen simulation isn't particularly accurate. Adjusting the toning of an ABW a QTR curve is an advanced process and most users would be better advised just to combine two curves.

The added complication, if you're after exact neutral, is the impact of the paper base color.  You may need to tweak for each paper.  Which is one of the complications of Piezography K7 inks.  Many people don't find their neutral inkset as neutral as they claim, even on Hahnemuhle Photo Rag, but with K7 you can't tweak, other than to change to a different paper. 

The Inkjetmall solution to this is their new Pro inkset, which has both warm and cool tonings that you combine to achieve various effects.  So you could achieve an exact neutral, although it may again be trial and error for each paper.  And you lose part of the attraction of Piezography, as you are reduced from seven to four shades on most printers.  But at least you can tweak

I think exact neutral is over-rated and boring.  Find a subtle toning that you like.
« Last Edit: March 24, 2018, 05:20:43 PM by Ferp »
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