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New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2014-11-09 by deanwork2003@...

I need to print out the 21-x4 random target and linearize it for a 9890 using K6 Piezo inks.


I can't find anywhere in my Eye One Pro 2 software to import this curve to do a reading of it for making a QTR curve ( no icc profiling needed). There seems to be no Measure Tool menu like the old software.


The old Profile Maker 5 software will not run on Modern Macs with intel processors. So how am I to use this Eye to linearize this target. I am using inks in positions other than those used for a normal K7 workflow because one of my Epson channels died.


John




Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2014-11-10 by richard@...

I literally wake up in the middle of the night thinking about this exact subject, and from all that I understand about this, you can not re linearize the Piezography .quad files. If you only moved the ink positions around in the printer then you can swap positions of the ink curves in the the .quad file without changing Linearization. 

The Measure Tool like function function of i1 Profiler is a bit wonky, but it is in the linearization workflow. Select CMYK printer and you will need to load a modified .txt ref file that has a value of 0 for every step of the C M and Y steps and the data from original 21x4 ref file the gray values in the  K steps of the new file format. I can post a link to the one I created when I get on my computer later today, but I found that the i1 device has a hard time reading the patches with the new software where it is flawless with the old measure tool in PM 5. I never have problems where it is "expecting to read x patches but only read y" The i1 pro 2 might work out to be better suited for it with this new software. 

Richard Boutwell

Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2014-11-10 by tyler@...

Richard, if you have the time I think it would be great for you to post the i1profiler approach to linearization in detail. We're quickly running out of current software, that works on current OSs, Xrite has no real reason to keep Colorport updated and could easily go the way of Measuretool. I would be happy to host the files and put a link to them in the links section here if t would help. Also I could build an Isis chart and text file to accompany if anyone needs that too. Obvioulsy there is a files section here too.
There are a few other niche pieces of software that will drive the devices and save out measurement texts and we may be reaching the point where all these options and info needs to be made easily available. We're dependent on being able to measure to make the most of QTR.
Tyler

Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2014-11-10 by richard@...

Tyler, I agree completely. I was talking to a friend about the legality of selling external hard drives that just "happens" to have a bootable version osx snow leopard and all the tools for making the curve creation process easier. It is a sad when companies try to "improve" software and end up ruining the best things about it. They go the way of the land rovers...

I haven't been able to dive too much into the format problems of the i1 profiler measurement data yet but I will make some noise about it when I sort it out (I'm 90% sure I am using the wrong setting someplace, but haven't been able to focus on it yet). Keith Cooper has some good info about it here:i1profiler for reading QTR linearising patches but the targets he has are limited to the 21 and 51 step charts. I've already created the 21x4 random chart, but I want to make sure it works before putting it out into the world.
Richard Boutwell


Re: [QuadtoneRIP] Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2014-11-11 by Michael King

Richard,

I literally wake up in the middle of the night thinking about this exact subject, and from all that I understand about this, you can not re linearize the Piezography .quad files.

So I was having the same thoughts about 6 years ago and knew there must be a way to do this because Jon Cone provides this as a service. After many months of wracking my brain and experimenting, I had a light bulb moment and realised the solution was staring me in the face all the time - you simply print and measure the linearization strip and that creates a response curve for your printer+ink+paper. Then you do a reverse lookup from that curve back the the quad file values for the linear steps you want to use.

So to give a simple example, if hypothetically you want to linearize at Lab Dmin,10,20,30,40,50,60,70,80,90,Dmax
you simply extract from the quad file the values that give you these Lab values on your response curve.

The only requirement is that original response curve has to be continuously increasing otherwise you can get duplicate values that this approach cannot resolve. But that's easy to avoid with a reasonable step width.

It works great and I was able to use linearization steps from 21 to 128+ with ease. 128+ is a special case and requires a consistent paper surface and the average of several sets of readings, which in turn is only practical with a sheet reading spectro.

To do this in practise you need to set up a spreadsheet to do the heavy lifting of searching for the values and filling in the gaps between the linearization points etc. I created one for my own use and shared a version with a few others to test - which all worked great. I was planning to develop a web based service to do this cheaply for others, but I got waylaid by other more financially pressing projects. I've been thinking for the last year or two that I should share more widely the work I did, so others can use it.

When I've got some time over Christmas I will share the spreadsheets and some simple instructions.

Cheers,
Mike




Re: [QuadtoneRIP] Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2014-11-11 by Roy Harrington

For those on Mac's instead of trying to re-linearize K7 .quad files which is hard to do,
go the ICC route. Just create a custom grayscale ICC built on top of the existing .quad file.
Then print using this ICC. It has the same affect as relinearizing the curve plus you get the
color-management system matching the embedded profile in your image. This is
the best/ideal way to get screen-to-print matching assuming you are profiling your monitor.
Note that you really have to use Print-Tool on the Mac to get this all to work correctly.

The MeasureTool issue is still a pain -- I run Parallels on the Mac with WinXP running so
I run MT on that.

PCs can do this too but you've got to do your ICC conversions in Photoshop before
sending to QTRgui for printing. (most people seem to go the No CM route on PCs I think).

Roy
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--
Roy Harrington
roy@...
www.harrington.com

Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2014-11-11 by richard@...

Mike,

Thanks for your detailed explanation. That is essentially what I though the answer had to be, I just couldn't figure out how to go about doing it (my own damn limited skills with the maths)

I'd love to talk more with you about this by email when you have more time. I've spent the better part of a year creating, refining, and using excel templates to average multiple readings to get exact cross-over and linearization values for making 6-gray channel QTR profiles that come close to the long-tailed curves that Jon makes. Although the his curves make much smoother gradients, if you can average out the measurement variances, the qtr ones come really really close. The issue with the QTR curves is the shape for each channel changes abruptly at the top end so any mistakes are in the ink limits or cross-overs point make obvious bands on smooth gradients.

Anyway, I will work on getting the i1 profiler stuff sorted and get back to you.

Richard Boutwell



Re: [QuadtoneRIP] Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2014-11-11 by sanking@...

Roy's suggestion to "create a custom grayscale ICC built on top of the existing Cone .quad file" makes a lot of sense to me. Back engineering the Cone .quad profiles looks like an activity that would burn up a log of time.

Speaking as someone who has been there, if you make a mistake and mix the Cone shades incorrectly for any reason, and assuming you have a lot of ink, it might make more sense to just bit the bullet and create your own QTR profiles for the K7 ink set, especially if you already have equipment to linearize such as an iOne or Spyder Pirnt. It is basically a rather routine procedure that involves just adjusting the ink levels and then linearizing the profile. Frankly it is a lot easier to do than read about, you just have to start the process and eventually you will get there. I was reluctant to do this myself for a long time but once I got involved in the process I found that I could make my own profiles with the regular QTR tools that for all practical purposes match output quality from the supplied K7 .quad files.

Sandy

Re: [QuadtoneRIP] Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2014-11-11 by Steve Taylor

Hi Mike,

I was one of those people involved with testing of your original  
spreadsheet and I am anxiously awaiting the return of this method. I am  
available for any further testing if needed.

Thanks,
Steve Taylor

On Mon, 10 Nov 2014 17:09:58 -0800, Michael King drmrking@...  
[QuadtoneRIP] <QuadtoneRIP@yahoogroups.com> wrote:

> To do this in practise you need to set up a spreadsheet to do the heavy  
> lifting of searching for the values and filling in the gaps between the  
> linearization points etc. I created one for my own use and shared a  
> version with a few >others to test - which all worked great. I was  
> planning to develop a web based service to do this cheaply for others,  
> but I got waylaid by other more financially pressing projects. I've been  
> thinking for the last year or two that I >should share more widely the  
> work I did, so others can use it.



-- 
Using Opera's mail client: http://www.opera.com/mail/

Re: [QuadtoneRIP] Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2014-11-13 by richard@...

I finally got around to getting the reference chart updated and figuring out what I was doing wrong. The problem I was having earlier in the week was related to using the wrong module to read the test chart—I updated my version of i1 Profiler and it works just fine for reading the step wedges.

I tested it with prints made from the original tiffs that are included with the QTR download and they works just fine, and I did not need to use the updated target images that Keith Cooper recommends.

The output data works fine with the QTR-Linearize-Data script with the 21x4-random and 51-step gray as well.

Here is a link to the blog post with the dropbox link for the reference charts. I will update and test the other reference charts when I get a chance. I tend to use the either the 21x4-random or the 21-step-gray that I average with 6 readings so I created spreadsheets that reference the measurement data and then copy those to a separate .txt file that i plug into qtr-linearize-data. All that will be explained in more detail in the refined profile creation workflows I am writing up.

Richard Boutwell


Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2014-11-14 by richard@...

Sandy,

I tried using i1 profiler to measure the ink separation files for evenly slicing up the dmin-dmax for setting the ink limit for each different shade and automatically calculating the overlap points. i1 Profiler fails to read it since it "thinks" it should be getting a value close to the target but is getting something totally out of what the margin of error should be.

I have the same problem with ColorPort trying to measure the ink separation files and even created the 8-ink separation files in ColorPort to print them in calibration mode and created separate grayscale reference files for measuring the chart—at least that was the theory until each shade was so far off what the software was expecting that it wouldn't read it without throwing errors. The ink seps are only 21-step gray ramps so you can use the 21-step reference file to measure them in strip mode. i created custom ref files to measure full charts, them import them into a spreadsheets that easily graph the slope for each ink channel to determine optimal ink limits, calculates the overlap points, and then averages the linearization measurments).

Measure Tool doesn't seem to care what it measures as long as the beginning and end of the strip is right. I am trying to perfect my QTR Toolbox with custom reference files, test images, and spreadsheet templates before releasing it to the public, but having only one piece of outdated software that can do what I needs done makes it close to impossible (any software engineers out there want to help me out?)

Richard Boutwell

Re: [QuadtoneRIP] Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2014-11-14 by Steve Taylor

Hi Mike,

I replied to the group but my message has not shown up there yet. Anyway,  
I was one of those people involved with testing of your original  
spreadsheet and I am anxiously awaiting the return of this method. I am  
available for any further testing if needed.

Thanks,
Steve Taylor

On Mon, 10 Nov 2014 17:09:58 -0800, Michael King drmrking@...  
[QuadtoneRIP] <QuadtoneRIP@yahoogroups.com> wrote:

>
>
> Richard,
>>
>> I literally wake up in the middle of the night thinking about this  
>> exact subject, and from all that I understand about this, you can not  
>> re linearize the Piezography .quad files.
> So I was having the same thoughts about 6 years ago and knew there must  
> be a way to do this because Jon Cone provides this as a service. After  
> many months of wracking my brain and experimenting, I had a light bulb  
> moment and >realised the solution was staring me in the face all the  
> time - you simply print and measure the linearization strip and that  
> creates a response curve for your printer+ink+paper. Then you do a  
> reverse lookup from that curve back >the the quad file values for the  
> linear steps you want to use.
>
> So to give a simple example, if hypothetically you want to linearize at  
> Lab Dmin,10,20,30,40,50,60,70,80,90,Dmax
> you simply extract from the quad file the values that give you these Lab  
> values on your response curve.
>
> The only requirement is that original response curve has to be  
> continuously increasing otherwise you can get duplicate values that this  
> approach cannot resolve. But that's easy to avoid with a reasonable step  
> width.
>
> It works great and I was able to use linearization steps from 21 to 128+  
> with ease. 128+ is a special case and requires a consistent paper  
> surface and the average of several sets of readings, which in turn is  
> only practical with a >sheet reading spectro.
>
> To do this in practise you need to set up a spreadsheet to do the heavy  
> lifting of searching for the values and filling in the gaps between the  
> linearization points etc. I created one for my own use and shared a  
> version with a few >others to test - which all worked great. I was  
> planning to develop a web based service to do this cheaply for others,  
> but I got waylaid by other more financially pressing projects. I've been  
> thinking for the last year or two that I >should share more widely the  
> work I did, so others can use it.
>
> When I've got some time over Christmas I will share the spreadsheets and  
> some simple instructions.
>
> Cheers,
> Mike
>
>
>
>
>
>
> 



-- 
Using Opera's mail client: http://www.opera.com/mail/

Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-02-06 by jeff.grant@...

When I read this thread originally, a lot off it went over my head. Now that I am in the thick of it, it makes a lot more sense. Roy's suggestion to create an ICC profile and use it sounds great, particularly as my new 3880 and the IJM curve aren't producing a great linearisation.

My understanding is that I keep the image in GG2, and in Print Tool select Application Managed and the profile that I have built. Is that correct?

Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-02-08 by jeff.grant@...

Replying to my own post, it helps to convert your 21 step file to GG2.2 for piezography. I was printing untagged which was causing the odd results. Dumb mistake, after years of colour profiling, it never occurred to me to do GG2.2

Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-02-08 by brian_downunda@...

I'm coming to this a bit late. I'm on Windows (7) and so don't yet have the issues with the measure tool that Mac users seem to have.

I'm replying because I wanted to take issue with Roy's post. I think that he and Jon Cone mean different things when they talk about linearising a curve, and especially a piezo K7 curve, where we only have the .quad file.

When Jon says linear, he means a straight line through the luminosity readings. I don't believe that this is what Roy means. Over the years I've seen him talk about perceptually linear. I'm not sure precisely what that means, but I guess it has something to do with a screen to print match.

In order to illustrate my concerns, I did as Roy suggested. Here is a linearisation check of my R1900 using EEM. The chart is from a spreadsheet that Jon Cone has on his support site to plot linearisation. Readings are taken using an i1 Photo.

View image: EEM linearisation 1

View image: EEM linearisation 1
http://postimg.org/image/eqxa2vqut/ Link copy to clipboard http://s10.postimg.org/qssnx103d/EEM_linearisation_1.jpg Direct Link copy to clipboard
View on postimg.org
Preview by Yahoo

So I created an ICC profile from these results and then converted the 21x4 chart from GG2.2 to the ICC and reprinted and remeasured to see just how linear it was. This is what I got:

View image: EEM linearisation 2
View image: EEM linearisation 2
http://postimg.org/image/pb77lgvcl/ Link copy to clipboard http://s10.postimg.org/ebm09v4xl/EEM_linearisation_2.jpg Direct Link copy to clipboard
View on postimg.org
Preview by Yahoo

It has evened things out, but it's not linear in the sense that Jon Cone means it - it is linear in some other (perceptual?) sense. If you pay Jon his $99 for a custom profile what you'd get is a plot that tracked the straight pink line. I.e. the L values falling on a straight line.

So my question is, is there a way to linearise the .quad file like this? I.e. Like Jon does?

Michael King seems to have a way. I don't fully understand it. I have used spreadsheets in the past to tweak quad files, so what I'd really like to know is his methodology. (I've used them to lower the ink load for papers that were too thin to take what the K7 curve was laying down.)

Another way that I've been playing with today is to create a Photoshop curve that is the exact inverse plot of the linearisation data after converting to the ICC in the second image. I.e. so that it straightens out the grey line so that it lies right on top of the pink. So you convert to the ICC to remove the wriggles, and then you apply the PS curve to linearise. It should be possible in theory. I've had partial success - the top 80% is now straight, but the darkest 20% isn't. I need to check and play further.

So I am interested in Michael's appraoch. Incidentally Michael, I recall your discussion with Jon 6+ years ago. I took a copy and still read it occasionally.

B.

[If those images don't persist where I uploaded them, then I find somewhere else.p



---In QuadtoneRIP@yahoogroups.com, <roy@...> wrote :

For those on Mac's instead of trying to re-linearize K7 .quad files which is hard to do,
go the ICC route. Just create a custom grayscale ICC built on top of the existing .quad file.
Then print using this ICC. It has the same affect as relinearizing the curve plus you get the
color-management system matching the embedded profile in your image. This is
the best/ideal way to get screen-to-print matching assuming you are profiling your monitor.
Note that you really have to use Print-Tool on the Mac to get this all to work correctly.

The MeasureTool issue is still a pain -- I run Parallels on the Mac with WinXP running so
I run MT on that.

PCs can do this too but you've got to do your ICC conversions in Photoshop before
sending to QTRgui for printing. (most people seem to go the No CM route on PCs I think).

Roy
Show quoted textHide quoted text

--
Roy Harrington
roy@...
www.harrington.com

Re: [QuadtoneRIP] Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-02-08 by Terry Ritz

Jon's curves assume Gray Gamma 2.2 input files. Roy's curves assume linear input files. Two fundamentally different approaches using the same tool (Quad Tone RIP).

Terry.
Show quoted textHide quoted text
> On Feb 8, 2015, at 8:00 AM, brian_downunda@yahoo.com [QuadtoneRIP] <QuadtoneRIP@yahoogroups.com> wrote:
> 
> 
> 
> I'm coming to this a bit late.  I'm on Windows (7) and so don't yet have the issues with the measure tool that Mac users seem to have.
> 
> I'm replying because I wanted to take issue with Roy's post.  I think that he and Jon Cone mean different things when they talk about linearising a curve, and especially a piezo K7 curve, where we only have the .quad file.
> 
> When Jon says linear, he means a straight line through the luminosity readings.  I don't believe that this is what Roy means.  Over the years I've seen him talk about perceptually linear.  I'm not sure precisely what that means, but I guess it has something to do with a screen to print match.
> 
> In order to illustrate my concerns, I did as Roy suggested.  Here is a linearisation check of my R1900 using EEM.  The chart is from a spreadsheet that Jon Cone has on his support site to plot linearisation.  Readings are taken using an i1 Phot! o.
> 
> View image: EEM linearisation 1
> 
>  
> View image: EEM linearisation 1
> http://postimg.org/image/eqxa2vqut/ Link copy to clipboard http://s10.postimg.org/qssnx103d/EEM_linearisation_1.jpg Direct Link copy to clipboard &n! bsp;
> View on postimg.org
> Preview by Yahoo
>  
> 
> So I created an ICC profile from these results and then converted the 21x4 chart from GG2.2 to the ICC and reprinted and remeasured to see just how li! near it was.  This is what I got:
> 
> View image: EEM linearisation 2
>  
> View image: EEM linearisation 2   
> http://postimg.org/image/pb77lgvcl/ Link copy to clipboard http://s10.postimg.org/ebm09v4xl/EEM_linearisation_2.jpg Direc t Link copy to clipboard  
> View on postimg.org
> Preview by Yahoo
>  
> 
> It has evened things out, but it's not linear in the sense that Jon Cone means it - it is linear in some other (percept ual?) sense.  If you pay Jon his $99 for a custom profile what yo! u'd get is a plot that tracked the straight pink line.  I.e. the L values falling on a straight line.
> 
> So my question is, is there a way to linearise the .quad file like this?  I.e. Like Jon does?
> 
> Michael King seems to have a way.  I don't fully understand it.  I have used spreadsheets in the past to tweak quad files, so what I'd really like to know is his methodology.  (I've used them to lower the ink load for papers that were too thin to take what the K7 curve was laying down.)
> 
> Another way that I've been playing with today is to create a Photoshop curve that is the exact inverse plot of the linearisation data after converting to the ICC in the second image.  I.e. so that it straightens out the grey line so that it lies right on top of the pink.  So you convert to the ICC to remove the wriggles, and then you apply the PS curve to linearise.  It should be possible in theory.  I've had p! artial success - the top 80% is now straight, but the darkest 20% isn't.  I need to check and play further.
> 
> So I am interested in Michael's appraoch.  Incidentally Michael, I recall your discussion with Jon 6+ years ago.  I took a copy and still read it occasionally.
> 
> B.
> 
> [If those images don't persist where I uploaded them, then I find somewhere else.p
> 
> 
> 
> ---In QuadtoneRIP@yahoogroups.com, <roy@...> wrote :
> 
> For those on Mac's instead of trying to re-linearize K7 .quad files which is hard to do,
> go the ICC route.  Just create a custom grayscale ICC built on top of the existing .quad file.
> Then print using this ICC.  It has the same affect as relinearizing the curve plus you get the
> color-management system matching the embedded profile in your image.  This is 
> t he best/ideal way to get screen-to-print matching assuming you are pro! filing your monitor.
> Note that you really have to use Print-Tool on the Mac to get this all to work correctly.
> 
> The MeasureTool issue is still a pain -- I run Parallels on the Mac with WinXP running so
> I run MT on that.
> 
> PCs can do this too but you've got to do your ICC conversions in Photoshop before
> sending to QTRgui for printing.  (most people seem to go the No CM route on PCs I think).
> 
> Roy
> 
> -- 
> Roy Harrington
> roy@...
> www.harrington.com
> 
> 
>

Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-02-08 by richard@...

Like I said earlier in the thread, I have been kept awake with this problem off and on for the last few months/years and it all started clicking earlier last week. partly due to the conversation about the problems with QTRs linear "curve" and the reason for needing ICC profiles to match the print space to the working space. I still think using the ICC profile with QTR severely blocks up the shadows, so I was attempting to map the .quad values to a "modified gamma" curve and print without color management—kinda going in-between where there is an increased smooth transition to the dark shadows but not the hard dip that results in using the ICC profiles. The natural next step is to be able to map any existing .quad profile to different targets—either a straight linear line or "modified gamma". There is some problem if the original profile is "too far off" but what I have been testing is a way to get away from the QTR linearize function, and only use QTR to build the raw profile using the ink limits and gray overlaps. I just did a three print test series with K6 inks and that approach worked better than the standard QTR profile creation workflow of linearizing a raw curve with the 21 step target and then creating an ICC profile (or printing with just the straight line increase).

All this came about because I figured out that my 1430 I use for testing at home is so far out of whack that no profiles other people have created work for this printer. I am looking into getting it replaced but since I need to build profiles from scratch, i developed some tools and methods for making it easier. I then take what I am doing to the studio and test on a properly functioning 3800 with Cone inks, and a 9900 with Epson inks.

Anyway. I am still testing and refining all this so I don't want to get too far ahead of myself here, but I am working on something that could be very interesting, and could solve a lot of problems linearizing wonky printers, or just make the standard QTR workflow less prone to error. I am not sure how it would translate to digital negatives yet, but that might just be the next step.

Richard Boutwell

Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-02-09 by brian_downunda@...

I understand that. I understand it only too well. Indeed that was precisely the point of my post - that they *are* two entirely different philosophies about how to print monochrome using QTR.

Despite this, Roy's post suggested that you could mix these two different approaches, and use the ICC approach to linearise the Cone curves. As I demonstrated, you can't, or at least not in the way that he suggested and still work within the Cone approach. It's not that simple. I confess that I thought it was, but it tried it and see that it's not.

So two questions remain. 1. is there a way to linearise the Cone curves, in a way that Jon Cone would think is linear? Michael seems to have an approach. If you look at the second image I posted, you see that after conversion to the ICC, the luminosity values lie on a smooth curve. In theory it should be possible to apply a Photoshop curve which is roughly the inverse of the curve you see in that image. That's what I'm trying. Partial success so far.

2. I'd really like to get a better understanding of how two such eminent people in the monochrome world use the word "linear" to mean something so different. I understand what Jon Cone means - you see it in the linearisation plots. What does Roy mean?

Brian

---In QuadtoneRIP@yahoogroups.com, <t.ritz@...> wrote :

Jon's curves assume Gray Gamma 2.2 input files. Roy's curves assume linear input files. Two fundamentally different approaches using the same tool (Quad Tone RIP).

Terry.

Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-02-09 by brian_downunda@...

Richard, I don't understand everything in your post, but some of that may be different terminology and different software used by Mac and Win users. Like you, I've been working with Jeff recently on these issues recently, and tripped over this problem several times. Like you, I've struggled with this issue over a number of years, and made a few additional discoveries recently. I think I've also managed to confuse Jeff a little, rather than enlighten him.

I agree that conversion to the ICC darkens the image and blocks up the shadows, although the effect is image dependent and more noticeable in dark-toned, low-key images. But likewise I find that a straight K7 print in GG2.2 is often weak in the shadows, again with the effect being image dependent and more noticeable in dark-toned, low-key images. Jon Cone would describe this as "open shadows", but I think there's a difference between weak images and images with open shadows and smooth tonal transitions.

I've handled this in the past using a hybrid approach. I will often create two versions - one in GG2.2 where I turn on the soft proof and darken the shadows to taste, and another where I convert to the ICC, turn on the soft proof and lighten the shadows to taste. Sometimes I have to print both to deicide which works best.

I've got a standard photoshop curve that I use to lighten the shadows. I'd like a more scientific approach. That curve in the second plot image may give me a way to create one. Moreover, using a PS curve derived this way would enable me to choose any point between the Roy Harrington approach and the John Cone approach - by varying the opacity of that curves layer.

But I'm interested in other approaches. I don't know what you mean by "map the .quad values to a 'modified gamma' curve". Perhaps it's the same thing that I'm trying to do, but expressed differently. You think so?

But one thing that I don't intend doing is building my own K7 curves from scratch using the QTR curve creation tools. I think that risks losing too much of the benefits of K7 - the smooth tonal transitions.

Incidentally, I made a comment on your bwmastery blog about comparing ABW & QTR that is awaiting moderation.

Brian


---In QuadtoneRIP@yahoogroups.com, <richard@...> wrote :

Like I said earlier in the thread, I have been kept awake with this problem off and on for the last few months/years and it all started clicking earlier last week. partly due to the conversation about the problems with QTRs linear "curve" and the reason for needing ICC profiles to match the print space to the working space. I still think using the ICC profile with QTR severely blocks up the shadows, so I was attempting to map the .quad values to a "modified gamma" curve and print without color management—kinda going in-between where there is an increased smooth transition to the dark shadows but not the hard dip that results in using the ICC profiles. The natural next step is to be able to map any existing .quad profile to different targets—either a straight linear line or "modified gamma". There is some problem if the original profile is "too far off" but what I have been testing is a way to get away from the QTR linearize function, and only use QTR to build the raw profile using the ink limits and gray overlaps. I just did a three print test series with K6 inks and that approach worked better than the standard QTR profile creation workflow of linearizing a raw curve with the 21 step target and then creating an ICC profile (or printing with just the straight line increase).

....

Richard Boutwell

Re: [QuadtoneRIP] Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-02-09 by Ernst Dinkla

There is a distinction between linear in density (measurements) and what the eye sees as linear so a perceptual linearity (Luminosity of Lab). About ten years ago when the linearisation/profiling for QTR was discussed we suggested a perceptual approach and by that the ICC profiling basics are the easiest way to get there.

Tweaking that approach may be necessary too as Black Point Compression on shorter dynamic ranges of prints is not ideal, whether RC + BPC or Perceptual rendering is used. There have been discussions on that subject too I think. Different color engines in applications show some differences in those renderings too.

On the sideline here but were Paul Roark's, Eric Chan's profiles not more tweaked for similar reasons?

Before that approach there were some generic QTR profiles for resp matte and gloss paper and Roy then also created an alternative space for Gamma 2.2 to assign to B&W images, it was called Gray-Lab.icc. The RGB version RGB-Lab.icc. The Read Me file says:

>>Gray Working Space

The first is gray-lab.icc which is an abstract gray space to be used as your gray working space in Photoshop. It spaces the grayscale values linearly with respect Lab or Luminosity. As opposed to a Lab space which is for color this space is a single channel gray space with the same spacing as Lab. Compared to Gray Gamma 2.2 it displays slightly darker through the mid values but opens up the deep shadows from K = 90 to 100%.<<

So neither linear or Gamma 2.2 but closer to the last.

What should be the ideal workflow today is harder to say. Roy may shed a light on that.


Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm

December 2014 update, 700+ inkjet media white spectral plots




Show quoted textHide quoted text
On Mon, Feb 9, 2015 at 3:41 AM, brian_downunda@... [QuadtoneRIP] <QuadtoneRIP@yahoogroups.com> wrote:

I understand that. I understand it only too well. Indeed that was precisely the point of my post - that they *are* two entirely different philosophies about how to print monochrome using QTR.


Despite this, Roy's post suggested that you could mix these two different approaches, and use the ICC approach to linearise the Cone curves. As I demonstrated, you can't, or at least not in the way that he suggested and still work within the Cone approach. It's not that simple. I confess that I thought it was, but it tried it and see that it's not.

So two questions remain. 1. is there a way to linearise the Cone curves, in a way that Jon Cone would think is linear? Michael seems to have an approach. If you look at the second image I posted, you see that after conversion to the ICC, the luminosity values lie on a smooth curve. In theory it should be possible to apply a Photoshop curve which is roughly the inverse of the curve you see in that image. That's what I'm trying. Partial success so far.

2. I'd really like to get a better understanding of how two such eminent people in the monochrome world use the word "linear" to mean something so different. I understand what Jon Cone means - you see it in the linearisation plots. What does Roy mean?

Brian

---In QuadtoneRIP@yahoogroups.com, wrote :

Jon's curves assume Gray Gamma 2.2 input files. Roy9;s curves assume linear input files. Two fundamentally different approaches using the same tool (Quad Tone RIP).

Terry.


Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-02-09 by tyler@...

my understanding, in our little print world.. "linear" is only meaningful in the sense that it applies to some standard. These 2 approaches are really no different, but they linearize to 2 different standards, that's all. One LAB, one gamma 2.2. There isn't really a "best" way, these decisions all have pluses and minuses. TO be honest, because I use a different RIP, I work in grayscale dot gain 20%. I've had no problem printing to QTR standard LAB based curves, or Cone 2.2 based curves, buy preconverting- either to one or the other workspaces, or a qtr custom icc profile, or Roy's supplied LAB output profiles, for either method. If you use Print Tool, preconversion is not necessary.
Tyler

Re: [QuadtoneRIP] Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-02-09 by Roy Harrington

Hi All,

Hopefully I can add some more to this without creating more confusion. I think its worth a bit of background.

In QTR Linearization is a simple correction curve that results in a straight-line of L values when
plotted against a straight-line of grayscale values. This has been the principle right from the start. The idea
is to have consistent behavior over a wide range of curves. The correction curve is incorporated into the .quad values.
L-values (Luminosity from LAB) are based on human vision, evenly spaced L-values should be perceived as evenly spaced. There are mathematical formulas for this but its based on human studies not a math theory.

There are a couple of things to note about this. First the idea is to be able to edit images in say Photoshop such
that you know what the print will look like in the end. Back in the darkroom days you took notes so that you
could do the same thing when you made another print from the same negative. The beauty of a digital workflow is
that it';s at least conceivable that you can actually see (actually a bit of imagining) what you are going to get
before you print the image. So screen-to-print matching is always the ultimate goal -- within the limitations of
reflective paper versus a glowing screen.

When you edit/view an image in Photoshop or any other program, file have an embedded ICC profile that maps
the actual numbers in the file to an L-value that is displayed. The Color Management System is the big black box that
converts file numbers to screen numbers or to printer numbers in such as way to match L-values as much as possible.
With the screen this always going on all the time -- there's no disable. This is easy on a screen since you only
have to profile the screen once and all programs can use the same thing. This is all built into the OS (both PC & Mac).

With printers though there are lots of variables so the one-sizes-fits-all concept does not work much of the time.
So how does this all relate to printing B&W with QTR driver (or any other way)?

There are two main issues. The usual embedded profiles for editing -- both RGB and gray -- are all "idealized"
profiles, meaning they theoretically range from absolute white to absolute black neither of which are attainable.
Second, they all have various curves defining the match between gray value (K) and luminosity (L).
So there are always issues of compressing into dMin through dMax and matching the curve in between.

-------------
So that's the basic problem and there have been many varied ways to deal with it.

While Linearizing L-values makes a lot of sense, just NoCM mapping say GG2.2 to QTR driver linear on
matte paper results in noticeably lighter prints than you9;d think or want. -- because dMax is pretty low that end of
scale is farther from the ideal pure black. See the pink line in Brian's post -- the whole line is significantly
higher (i.e. lighter) than the 0-to-100 diagonal would be. Additionally the GG2.2 L-values are not linear
either so what you based editing the image on is different. I made a linear L-value profile Gray Lab that helped
a little but still the mapping is not the best.

Since Jon Cone started making his own .quad profiles he's reportedly made them to better match GG2.2 with
NoCM. I'm not sure of the exact mapping so its hard to comment for sure.

Others such as Paul Roark have just designed their own PS curves that can be applied before printing.
Both of these are simply color management hand-done and can work just fine.

Color managed ICC profiles with Black Point Compensation are the industry standard way to do this mapping
in the most flexible way. Most everything CM talks about color but B&W fits into this just fine too.
On a PC this would always require a manually applied Convert-To-Profile so its a bit of a hassle. On a Mac
this worked quite well up through CS3 but then that was messed up from CS4 on and later OSX versions.
Eventually I wrote Print-Tool for the Mac so I could get back to the old working method.
If you read the BPC doc that Ernst posted there's lots of confusing technical info but the bottom line is the
mapping in XYZ space (for B&W really only Y) makes for perceptually better matching of screen-to-print.
Note that nothing is perfect -- see Brian's second image for the curved black line -- i.e. the BPC mapping.
Throughout most of the range its closer to diagonal but curves at the bottom compressing the shadows a bit.
So, yes, it doesn't work miracles but its the "best" compromise. If you want more open shadows you've
got to edit your file to do that -- I think you have the best control doing this. Soft-proofing with simulate
ink-black can help visualize if you like. -- another gotcha here is use the RGB-Matte-Paper because the
Apple CMS used by Print-Tool doesn't support this in grayscale (argh!). (I think you can pretty much get over
needing the soft-proof and just visualize/imagine how to edit)

-------

Finally to come full circle on the discussion. K7 .quad files are not re-linearizable by QTR driver because
there is no .txt/.qidf file. I think they are all pretty good to start with so usually this is not an issue.
But adding an ICC profile built on the K7 curve you have gets you the full ICC screen-print matching
regardless of how "linear" the K7 works on a different paper or different printer. This is by far the most
straightforward method on a Mac with Print-Tool but a bit more hassle on a PC.

Roy

Show quoted textHide quoted text
On Sun, Feb 8, 2015 at 9:56 AM, richard@richardboutwell.com [QuadtoneRIP] <QuadtoneRIP@yahoogroups.com>; wrote:


Like I said earlier in the thread, I have been kept awake with this problem off and on for the last few months/years and it all started clicking earlier last week. partly due to the conversation about the problems with QTRs linear "curve" and the reason for needing ICC profiles to match the print space to the working space. I still think using the ICC profile with QTR severely blocks up the shadows, so I was attempting to map the .quad values to a "modified gamma" curve and print without color management—kinda going in-between where there is an increased smooth transition to the dark shadows but not the hard dip that results in using the ICC profiles. The natural next step is to be able to map any existing .quad profile to different targets—either a straight linear line or "modified gamma". There is some problem if the original profile is "too far off" but what I have been testing is a way to get away from the QTR linearize function, and only use QTR to build the raw profile using the ink limits and gray overlaps. I just did a three print test series with K6 inks and that approach worked better than the standard QTR profile creation workflow of linearizing a raw curve with the 21 step target and then creating an ICC profile (or printing with just the straight line increase).

All this came about because I figured out that my 1430 I use for testing at home is so far out of whack that no profiles other people have created work for this printer. I am looking into getting it replaced but since I need to build profiles from scratch, i developed some tools and methods for making it easier. I then take what I am doing to the studio and test on a properly functioning 3800 with Cone inks, and a 9900 with Epson inks.

Anyway. I am still testing and refining all this so I don't want to get too far ahead of myself here, but I am working on something that could be very interesting, and could solve a lot of problems linearizing wonky printers, or just make the standard QTR workflow less prone to error. I am not sure how it would translate to digital negatives yet, but that might just be the next step.

Richard Boutwell





--

Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-02-10 by brian_downunda@...

Thank you all for your comments. I have a feeling I'm on an epic voyage of REdiscovery. I've used QTR for just on 10 years, and in fact next month will be the 10 year anniversary of paying my $50. Some of this is starting to come back to me. In the early years I was using K2 and K3 curves. I recall when those generic profiles that Ernst referred to were released, as they were a revelation and an aid to workflow. I'm starting to recall the discussions about perceptual linearity. However for the past nearly 7 years I've used mainly K6 or K7 and so have forgotten a lot of it.

@ Tyler
BTW, I'm on Win so I don't use print tool (sadly) and so have to pre-convert.

@Roy
Thank you for such a thorough exposition. Some replies.
. I'm in complete agreement that the NoCM & GG2.2 workflow leads to a print with weak shadows, at least initially before consequential edits, although the extent of this is very much image-dependent. I don't think that Jon has changed things much - he still wants K6/K7 curves that track that pink line exactly.
. I also agree that the CM & ICC workflow compresses the shadows, but this also is image-dependent.
. So for some years I've used a couple of techniques that try to work somewhere between these two. Putting or keeping weight into the shadows, but not too much and without losing detail of blocking up. Sometimes working in GG2.2 without CM and sometimes working in ICC with CM.
. I'm all for soft-proofing. It is the big advantage of the digital age over the wet darkroom, IMHO.
. And I think that converting to ICC does give the best screen to print match, but at a cost of the shadow detail, which I need to recover.
. It also linearises the printer, according to one usage of the word.
. Jon's approach also uses soft-proofing, but without CM you need to use the "preserve numbers" option. I usually don't find this as convenient a workflow, and it's harder to deal with a printer that is displaying non-linear behaviour, as in my first image.

So what's my point? Well, I'm trying to do two things, with Photoshop curves.
(i) I want to correct the non-linear behaviour of my printer, at least in the Jon Cone sense, ie. have it printing on the pink line. I think I can do this with a PS curve. I'm still refining it.

(ii) I want to be able to use a workflow that enables me to choose a point between linear in the Roy sense and linear in the Jon sense. I.e. a line that is as straight as possible between the pink and black lines in chart 2.

I've seen the Roark stuff. http://www.paulroark.com/BW-Info/QTR-Printing-Windows.pdf As you say, his curves simulate applying an ICC. I guess I'm trying to re-derive that curve for my papers more scientifically. Once I've got that I can choose what opacity to use for that curve. I can also create an inverse of that curve, which I can then use when I convert an image to the ICC, which also "linearises" the image, and then apply the inverse curve with some percentage opacity to partly reverse the ICC conversion.

For a number of years I've tried both of these approaches using the Roark curve and its inverse as rough approximation of the CM approach and I've been happy with the results, but want to improve on them.

Summary: Converting to GG2.2 opens the shadows and converting to the ICC closes them. I'm looking for a workflow that allows me to pick a point between these two and vary it as I choose. I'm also looking for something that allows me to iron out the idiosyncracies of my printer. I'm trying to use PS curves, but am open to alternatives.

But I still take issue with Roy's statement in his first post that "Just create a custom grayscale ICC built on top of the existing .quad file. Then print using this ICC. It has the same affect as relinearizing the curve plus you get thecolor-management system matching the embedded profile in your image." Yes it's linear, but it's a different kind of linear to that which the original Cone .quad was aiming for. I think that needs to be clear.

Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-02-16 by brian_downunda@...

My last couple of long posts seem to have stopped this thread dead. Let me try to restart it with a slighly shorter one that returns to the question of the OP.

I have taken Jon Cone's linearisation checker spreadsheet and extended it so that it spits out the points for a photoshop curve that is the inverse of the one you get from plotting the measured L values. I then printed the 21x4 with this curve applied and remeasured the linearity and it was pretty much dead straight along that pink line. I tested this for several papers and it worked in each case. So this provides one solution.

However it does mean remembering to apply the curve for each image. It would be a lot simpler if this curve could be applied to the .quad file. But the photoshop curve is L whereas the .quad file has ink values, which I assume are more akin to density. Undeterred I made a couple of attempts. I used a cubic spline to interpolate all 256 points from the 21 linearity measurements.

I had some success. The straight L curve doesn't provide enough of a correction, so I migrated my inverse curve calculations from L to density and applied them to the .quad file. I got fairly close, but not quite close enough. So what am I missing? For the photoshop curve, I had to apply a scaling factor to translate a dmin-to-dmax curve into the 0-255 range. I suspect that I'm missing some sort of scaling factor here as well. Until I can get this to work, I'm using the photoshop curve to linearise.

I've read Mike's post below several times and I still don't quite understand his methodology. I don't quite get his reverse lookup. Mike - if you're still around, I'm happy to exchange spreadsheets and explain my methodology in more detail. It must be possible to get this to work somehow, other than paying $99 per paper.

B.


---In QuadtoneRIP@yahoogroups.com, <drmrking@...> wrote :

Show quoted textHide quoted text
After many months of wracking my brain and experimenting, I had a light bulb moment and realised the solution was staring me in the face all the time - you simply print and measure the linearization strip and that creates a response curve for your printer+ink+paper. Then you do a reverse lookup from that curve back the the quad file values for the linear steps you want to use.

So to give a simple example, if hypothetically you want to linearize at Lab Dmin,10,20,30,40,50,60,70,80,90,Dmax
you simply extract from the quad file the values that give you these Lab values on your response curve.

The only requirement is that original response curve has to be continuously increasing otherwise you can get duplicate values that this approach cannot resolve. But that's easy to avoid with a reasonable step width.

It works great and I was able to use linearization steps from 21 to 128+ with ease. 128+ is a special case and requires a consistent paper surface and the average of several sets of readings, which in turn is only practical with a sheet reading spectro.

To do this in practise you need to set up a spreadsheet to do the heavy lifting of searching for the values and filling in the gaps between the linearization points etc. I created one for my own use and shared a version with a few others to test - which all worked great. I was planning to develop a web based service to do this cheaply for others, but I got waylaid by other more financially pressing projects. I've been thinking for the last year or two that I should share more widely the work I did, so others can use it.

When I've got some time over Christmas I will share the spreadsheets and some simple instructions.

Cheers,
Mike




Re: [QuadtoneRIP] Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-05-17 by tracy@...

"For those on Mac's instead of trying to re-linearize K7 .quad files which is hard to do,
go the ICC route. Just create a custom grayscale ICC built on top of the existing .quad file.
Then print using this ICC.

...The MeasureTool issue is still a pain -- I run Parallels on the Mac with WinXP running so
"

OK: I hate to be the dullest blade in the drawer, but here goes...

I'm using Piezography. Right now I create my image and print it thru PrintTool w/NCM. Seems OK to me, but if I can make it better. (I just got a shiny new i1 Photo Pro, so I want to play...)

Does "... create a custom grayscale ICC built on top of the existing .quad file" mean to print out a target thru a .quad file for a given paper, just as if I were printing a photo? Then measure that result into an .ICC profile?

If so, then will such a profile make use of all the K7 inks when I print? Exactly where do I choose to use that profile? In the PS dialog, or in the PT driver?

Doesn't an ICC profile run off to the Profile Connection Space, which is a color space? Are not the Piezography curves just curves (amounts of ink) and doesn't that completely bypass the PCS?

I feel like this 70 year old brain is beating around the edges of what's being said here. Just not wrapping my brain around how this works, out here in the real world, one step after another.

and then I get to "The MeasureTool issue is..." Now I'm really confused. I thought the Measure Tool wasn't involved in the creation of an ICC profile. Wouldn't that be used if I were trying to directly linearize the curves instead of generate a profile?

Likely someone is slapping their forehead right now, but if I don't ask, I won't learn...

Thanks for your patience.

Re: [QuadtoneRIP] Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-05-17 by jeff.grant@...

Tracy,

Brian is travelling at the moment so he may not answer for a day or two. Richard Boutwell cracked what you need to do to use TXT files with i1Profiler on the Mac a while back. Here's a link to his site: i1 Profiler and 21x4-random QTR Step Wedges This is what you are gong to be printing and measuring to make profiles along with the QTR Create ICC tool.

i1 Profiler and 21x4-random QTR Step Wedges
Use the current version of i1-Profiler to linearize custom Quad Tone Rip profiles
View on www.bwmastery.com
Preview by Yahoo

Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-05-17 by brian_downunda@...

I am indeed travelling, and typing on a tablet is tedious. I will give you my answer your questions in a few days. Others may chime in. Be warned that there are two quite different philosophies here, and multiple opinions about how to apply them. I will do my best to explain simply.

Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-05-24 by brian_downunda@...

I'll do my best to answer this question simply.

The aim in creating a QTR curve is to make it linear. That is, you want the luminosity values that it prints to lie on a straight line when you graph them. This gives you an even separation of tones in your print. You print out a test chart like the 21x4 chart that ships with QTR using the curve in question, and measure the luminosity results (using Measure Tool or similar software) and plot them. If you look at the two charts I posted in post 17 of this thread, you'll see a pink line. You want the luminosity values that you plot - the black lines - to lie on this pink line or fairly close to it.

If you create QTR curves using the curve creation tools that ship with QTR, then this is easy to do, assuming that you have a spectrophotometer like an i1. Printing and measuring the 21x4 gives you the linearisation numbers, and you can append them to the curve. Reprint using the updated curve and remeasure, and you'll get a the black line to sit on or close to the pink. There are various tutorials around about how to do this.

But K7 curves don't work like this. They are created by Jon Cone and InketMall using their own proprietary software, so you can't use the QTR curve creation tools to re-linearise them.

So what to do if you need to re-linearise a K7 curve that needs it? Well, (i) you can pay IJM $99 per curve to create custom curves for your printer. (ii) An alternative that various people here have adopted is to create their own custom spreadsheets to hack the .quad files that contain the curves and do some approximate re-linearisation.

Roy is suggesting (iii) - when you print the 21x4 and measure the patches (Measure Tool again), you can also use the results to create an ICC profile. QTR ships with QTR-Create-ICC which does this. You drop the measurements on this program and you get an ICC. Again, there are instructions around about how to do this. You've got a shiny new i1 Photo, so give it a try. You can at least use the ICC for soft-proofing (see below).

Now the question is, how you use the profile? Well, one thing you can do is use the ICC to soft-proof how the image will print. In the Jon Cone workflow, you *do not* convert to this profile, so in Photoshop you must select "preserve numbers" in your soft-proofing options (I'm not sure whether you can do this in Print Tool, even though that's what you'll print with). This works, as you can see how the image will print, including the effects of any non-linearity in the curve. You can edit the image to compensate for the non-linearity, but your curve is still non-linear.

What Roy is suggesting is to *convert* the image to the ICC for printing. What effect will this have? Well in that post 17 of mine, I demonstrated this. The first chart is from measuring my curve, and as you can see it's not very linear. For the second chart, I converted the 21x4 to the ICC I created from the initial measurements, printed it and remeasured. You can see that doing this has evened out all the wiggles in my curve - it's nice and smooth. But it's a long way from that pink line. Since it's below it this means that the image will print darker after the conversion. You can use your new ICC to soft-proof this, but this time leave "preserve numbers" unchecked.

Why is the ICC designed to have this effect? Because Roy designed the ICCs to enable you to print the file in a "perceptually linear" manner. I.e. one that looks roughly like it does on the screen. But to do this it is compressing the shadows quite a lot, and even Roy conceded above (post 24) that this compresses the shadows, and you may need to edit them to compensate.

So that's why you'd tell Print Tool (not PS) to convert the image to the ICC rather than print in GG2.2 - to straighten out the wiggles in a non-linear curve. And that's also why you wouldn't do it - because it darkens the print and looses shadow detail (how much it does this will depend on the image).

So as I said in my interim reply, there are two quite different philosophies in play here. Jon Cone places a premium on preserving shadow detail and opening the shadows, and tells you *never* to convert to the ICC, only to use it for soft-proofing. But if you follow this workflow, you've got no (easy) way to re-linearise the K7 curve. You've got to pay $99. Or develop a spreadsheet to hack the .quad file.

Roy on the other hand suggests that you create an ICC and use Print Tool to convert the image to it for printing. If you've got an i1 or similar then this is easy, and it gives you a form of re-linearisation. But you'll get quite a different (darker) print to the intentions of the piezography system.

Does linearisation matter? Well It gives you a known starting point and reference point for printing. It means you're not editing every image to compensate for curve non-linearity.

This is long, but I've tried to make it simple.


---In QuadtoneRIP@yahoogroups.com, <tracy@...> wrote :

"For those on Mac's instead of trying to re-linearize K7 .quad files which is hard to do,
go the ICC route. Just create a custom grayscale ICC built on top of the existing .quad file.
Then print using this ICC.

...The MeasureTool issue is still a pain -- I run Parallels on the Mac with WinXP running so
"

OK: I hate to be the dullest blade in the drawer, but here goes...

I'm using Piezography. Right now I create my image and print it thru PrintTool w/NCM. Seems OK to me, but if I can make it better. (I just got a shiny new i1 Photo Pro, so I want to play...)

Does "... create a custom grayscale ICC built on top of the existing .quad file" mean to print out a target thru a .quad file for a given paper, just as if I were printing a photo? Then measure that result into an .ICC profile?

If so, then will such a profile make use of all the K7 inks when I print? Exactly where do I choose to use that profile? In the PS dialog, or in the PT driver?

Doesn't an ICC profile run off to the Profile Connection Space, which is a color space? Are not the Piezography curves just curves (amounts of ink) and doesn't that completely bypass the PCS?

I feel like this 70 year old brain is beating around the edges of what's being said here. Just not wrapping my brain around how this works, out here in the real world, one step after another.

and then I get to "The MeasureTool issue is..." Now I'm really confused. I thought the Measure Tool wasn't involved in the creation of an ICC profile. Wouldn't that be used if I were trying to directly linearize the curves instead of generate a profile?

Likely someone is slapping their forehead right now, but if I don't ask, I won't learn...

Thanks for your patience.

Re: [QuadtoneRIP] Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-05-24 by Ciprian

Jon Cone places a premium on preserving shadow detail and opening the
    shadows, and tells you *never* to convert to the ICC, only
    to use it for soft-proofing.  But if you follow this workflow, you've got no (easy) 
    way to re-linearise the K7 curve.  You've got to pay $99.  Or develop a
    spreadsheet to hack the .quad file.

<sigh> And this is the part where all the stories end-up with a big "here be dragons!" sign. 

Brian, is there some reference some theoretical framework about the math involved, about the algorithm, something that would point out to the steps needed to linearize a K7 ink set? In other words, why is that everyone seems to be so afraid of the math involved in the linearization process? What's the catch? Are we talking incredible complex equation systems or something like that?

Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-05-25 by brian_downunda@...

True, while none of us understand precisely how Jon Cone creates K7 curves, several of us claim to have ways of hacking or tweaking the .quad files. But no-one has said precisely how they do it. Michael King has never published his spreadsheets. Richard Boutwell is writing a book, although it's not clear to me whether he has a way to re-linearise a K7 curve from IJM, or is creating them himself from scratch using the QTR curve creation tools.

For my part, I've got a spreadsheet or two, but I've been hesitant to document this because I don't fully understand the maths. There's no "incredible complex equation", although it's a little messy. I can calculate ideal and actual densities for a K7 curve, but I can't work out how to translate these into modified values in the .quad file. Well I can, but my current approach doesn't linearise the .quad file sufficiently. I'm missing something. One day I might ask Roy about the bits I don't understand. So I took a different route.

I am setting up a B&W blog (isn't everybody?) where I will probably document this. But I am time-poor at present and will be offline for much of the next few months. So here is a sketch outline of how I do it at present.

1. I create a dummy curve in QTR that uses only one ink - Shade 1, and let it range from 0 to 90%. I use an existing curve as the base, but strip out all the linearisation etc data. I instruct QTR to generate a .quad file. I put this to one side as a reference point for step 3.

2. I then take the linearisation data that I get from dropping the measurements of my 21x4 chart (I actually use a 51x3 chart) onto QTR-Linearize-Data, and input this data into my dummy curve. I regenerate the .quad file.

3. So now I have two .quads - one generated without the linearisation data and one with. In a spreadsheet I take the ratio of these two columns of numbers for shade 1, and scale the values of each of the seven shades in the real K7 .quad file by this set of 256 ratios. Setting up a spreadsheet to do this is a little tedious, but once you've done it, you can reuse it. The relinearised .quad isn't quite as straight as a $99 curve from IJM, but by golly it's close. Certainly close enough IMHO.

I'd like to be able to do this entirely in a spreadsheet using the measurements of the 21x4, i.e. without resorting to QTR and dummy curves. I've come close, but there's something small I don't understand. Perhaps I will ask Roy when I have more time. Anyway, you can either try to understand and replicate what I've done, or wait a couple of months until I blog all this, with the necessary files.

No dragons, just the Triantiwontigongolope.
"When first you come upon it, it will give you quite a scare,
But when you look for it again, you find it isn't there."


---In QuadtoneRIP@yahoogroups.com, <ciprian333@...> wrote :

Jon Cone places a premium on preserving shadow detail and opening the
shadows, and tells you *never* to convert to the ICC, only
to use it for soft-proofing. But if you follow this workflow, you've got no (easy)
way to re-linearise the K7 curve. You've got to pay $99. Or develop a
spreadsheet to hack the .quad file.

<sigh> And this is the part where all the stories end-up with a big "here be dragons!" sign.

Brian, is there some reference some theoretical framework about the math involved, about the algorithm, something that would point out to the steps needed to linearize a K7 ink set? In other words, why is that everyone seems to be so afraid of the math involved in the linearization process? What's the catch? Are we talking incredible complex equation systems or something like that?

Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-05-25 by Lutsky, Berel


Responded to this off line last week, but I am stuck in the airport for too long today, So here's my 2 cents. I am a long time user of Piezography, through several versions and generations of development. Including the stage before QTR. What you are getting is a turnkey BW system that has been engineered from the beginning to maximize the potential of the ink sets and the Epson print driver. The question that one needs to answer when subjecting this to a DIY process is how much time do I want to spend making curves and/or mixing inks vs. making prints. The real short answer is that the IJM K6/7 curves provided free to QTR users will, 99% of the time will not need any linearization. You can view the curves in QTR, and wil see right away that they look different from those created in QTR, both in their shape and overlap. There are special instructions for using them in QTR which should be followed for best results, Only problem and it is a small one is that there is no PS soft proof available. Two solutions for this Hard way is a workaround to create an ICC profile which can only be used for soft proofing-look at the Northlight website- the easy way is to set a calibrated monitor to a soft proof profile a
Of gray Gamma 2.2 for viewing. This will give you a good look at output densities and shadow detail. This works well most of the time, with the curves provided. If your paper is not profiled choose something similar. The needs of specific images/papers can usually be addressed with a slight curve adjustment in PS or LR. Try to print to the needs of your image, not a step wedge,

Berel Lutsky
Associate Professor of Art
UW Manitowoc
920-683-4735

Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-05-26 by brian_downunda@...

We know that it's supposed to be a turn-key system, Berel, but in my experience and that of another new K7 user, your 99% number is *way* too high. I too much prefer to print images than step wedges, which gets tedious very quickly. I was dealing with the "needs of specific images/papers ... with a slight curve adjustment in PS", but it's tedious for every image. What I've done to the .quad file is conceptually the same thing, and it's much more convenient.

The soft proofs, while approximate, are invaluable, and save a lot of ink and paper.

I don't begrudge Jon his $99 (somewhat higher in $AUD), given the amount of embedded IP. But posting profiles from the other side of the planet is tedious. And for those using desktop printers and multiple papers, getting a new printer is probably more economical that a complete reprofile. I may consider some if and when he goes back to giving us the option of scanning our own charts, but that's unlikely. I know at least one photographer who runs a large format printing service who moved away from piezo partly over this issue. I'm not convinced that the current approach is encouraging wider adoption of the system.


---In QuadtoneRIP@yahoogroups.com, <berel.lutsky@...> wrote :


Responded to this off line last week, but I am stuck in the airport for too long today, So here's my 2 cents. I am a long time user of Piezography, through several versions and generations of development. Including the stage before QTR. What you are getting is a turnkey BW system that has been engineered from the beginning to maximize the potential of the ink sets and the Epson print driver. The question that one needs to answer when subjecting this to a DIY process is how much time do I want to spend making curves and/or mixing inks vs. making prints. The real short answer is that the IJM K6/7 curves provided free to QTR users will, 99% of the time will not need any linearization. You can view the curves in QTR, and wil see right away that they look different from those created in QTR, both in their shape and overlap. There are special instructions for using them in QTR which should be followed for best results, Only problem and it is a small one is that there is no PS soft proof available. Two solutions for this Hard way is a workaround to create an ICC profile which can only be used for soft proofing-look at the Northlight website- the easy way is to set a calibrated monitor to a soft proof profile a
Of gray Gamma 2.2 for viewing. This will give you a good look at output densities and shadow detail. This works well most of the time, with the curves provided. If your paper is not profiled choose something similar. The needs of specific images/papers can usually be addressed with a slight curve adjustment in PS or LR. Try to print to the needs of your image, not a step wedge,

Berel Lutsky
Associate Professor of Art
UW Manitowoc
920-683-4735

Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-05-26 by brian_downunda@...

Thanks for letting me know. That's a relief. It's hard to explain this simply, esp when I don't know how much prior knowledge the reader has. On occasion I have managed to confuse and lose people with my long posts / messages.

Re: [QuadtoneRIP] Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-05-27 by Ernst Dinkla

Not for QTR but to create B&W profiles for my HP Zs + Qimage Ultimate with QTR's profile creator. For measuring I'm using PatchTool meanwhile. The latest version of MeasureTool running on Windows 7 delivered locked measurement files. Could not figure out what caused that. I can run it on the XP + Virtual PC emulation in W7 but that gives more trouble with file exchanges. ColorPort created other issues, mainly with the averaging of target patches. ArgyllCMS does not do that well either and I have to do more tweaking on the files for the QTR tools. PatchTool is way more versatile and I trust Babelcolor on keeping it up to date. However it is not free, but my time is neither. For creating my own targets I actually use patch data made with ArgyllCMS, import them in PatchTool, rearrange them in PatchTool and after printing measure them with PatchTool. There is an averaging feature in PatchTool but with the 34 steps target I use now it does not bring more quality in the profile as far as I could measure. Using an Eye1 Pro but PatchTool and ArgyllCMS cover the latest spectrometers too.

Met vriendelijke groet, Ernst

December 2014 update, 700+ inkjet media white spectral plots


Show quoted textHide quoted text
On Sun, May 17, 2015 at 7:37 AM, tracy@... [QuadtoneRIP] <QuadtoneRIP@yahoogroups.com> wrote:

"For those on Mac's instead of trying to re-linearize K7 .quad files which is hard to do,

go the ICC route. Just create a custom grayscale ICC built on top of the existing .quad file.
Then print using this ICC.

...The MeasureTool issue is still a pain -- I run Parallels on the Mac with WinXP running so
"

OK: I hate to be the dullest blade in the drawer, but here goes...

I'm using Piezography. Right now I create my image and print it thru PrintTool w/NCM. Seems OK to me, but if I can make it better. (I just got a shiny new i1 Photo Pro, so I want to play...)

Does "... create a custom grayscale ICC built on top of the existing .quad file" mean to print out a target thru a .quad file for a given paper, just as if I were printing a photo? Then measure that result into an .ICC profile?

If so, then will such a profile make use of all the K7 inks when I print? Exactly where do I choose to use that profile? In the PS dialog, or in the PT driver?

Doesn't an ICC profile run off to the Profile Connection Space, which is a color space? Are not the Piezography curves just curves (amounts of ink) and doesn't that completely bypass the PCS?

I feel like this 70 year old brain is beating around the edges of what's being said here. Just not wrapping my brain around how this works, out here in the real world, one step after another.

and then I get to "The MeasureTool issue is..." Now I'm really confused. I thought the Measure Tool wasn't involved in the creation of an ICC profile. Wouldn't that be used if I were trying to directly linearize the curves instead of generate a profile?

Likely someone is slapping their forehead right now, but if I don't ask, I won't learn...

Thanks for your patience.


Re: [QuadtoneRIP] Re: New to Linearize Piezo K7 inks with Eye One 2 X-Rite software

2015-06-09 by richard@...

There isn’t some kind of secret or overly-complicated math (ok, it is some complicated math) that needs to happen to relinearize a quad file, but it is a lot of work, and it took me many hours (six months?) and more than a few boxes of paper to get to something I feel is a “perfected prototype”.

I made a long post on my site that has some overlap with what I wrote here: http://www.bwmastery.com/blog/2015/relinearize-quad-curves

To answer Brian’s question and to clear up what I’ve been able to do through testing and refining a number of different methods:
  • For creating QTR profiles I do have a way of somewhat automatically filling in the ink limit and overlaps for partitioning k6/k7 inks using the standard QTR Curve Creation tools and workflow (as well as some additional gray gamma gray overlap settings). This is information that can be found and pieced together from various sources online. I just did it in a more logical, repeatable, and refined manner, and this is what will make up some of the upcoming book. Some of that is in the post here: 
http://www.bwmastery.com/blog/2015/in-search-of-the-perfect-qtr-profile

  • I also have a way of parsing out the Piezography master curves to 21 control points so ACV curves can be created and edited in Photoshop and then assigned to each channel in a QTR ink descriptor file (doing this with the ink\_curve= input bypasses the standard QTR gray ink partitioning functions and creates new master quad curves based on each of the ACV curves). You can see how this looks in an ink descriptor file in one of the screenshot illustrations in the post about relinearizing)

  • When I have made my own profiles from the master curves I use a K curve that was created with an ACV and lowering the ink limit so there is not as much ink being loaded up at the very end of the scale. - Those new master curves can then be linearized with my spreadsheet template/prototype that takes in an existing .quad file and a 51x3 measurement data file and then automatically creates a correction curve and arrives at a new linearized set of quad curves.

  • If all you had were those ACV curves for each ink in the QIDF, you could print and measure the 21x4 step wedge, place it in the linearize= line and with a bit of luck you could create your own custom “piezography-style” curves with just the tools available in QTR. The problem is that linearizing with the QTR tools doesn’t work consistently and you get more errors than it is worth. Ask me how I know…)

  • Alternatively, with my method I can introduce a slight compression in the shadows and a different shaped gray curve the new quad curves are mapped to, but that does not block up like using the color managed workflow for “relinearizing”

  • Since the my method works directly from an existing .quad file it means that I can also relinearize existing Piezography curves for papers aging or out of spec printers, or to map them to a different shaped gray curve (I’ve done this as a test for myself and a few different people now).

  • The new linearized quad values are then pasted into a text file template with the correct header information for the printer and number of inks being used and is then saved with the .quad extension and installed like usual.

  • It is also possible for me to create custom Quad Profiles from the existing Piezography master curves (although the higher limit of \~60% in the K channel is a problem and can cause reversals from 96%-100%.) That is why I think there is something about the ink limits for the custom curves being set for whatever the black point or dmax is and then the other steps are scaled up/down (or left/right depending on how you look at it).

Some of the maths involved with the piecewise curve fitting and spline functions are over my head, but the steps of arriving at an accurate correction curve and interpolating new quad values aren’t. Once I got the correction curve correct it was then just a matter of applying different spline interpolation functions to arrive at the correct quad value for every 256 points on the scale.

I apologize for being somewhat cagey about the details of how exactly this all works, but it does represent several months of work and now I am working on it possibly being developed into a standalone application. Until that is finished, I am offering a relinearization service through my bwmastery site.

I also created an updated single 51 step target and i1 profiler workflow for measuring the target single 51-step target 3 times (rather than printing the same target 3 time and measuring each target once).


Richard Boutwell



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