Don hutcheson's equations and npdc graphs, and color management

Don hutcheson's equations and npdc graphs, and color management

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disbellj

Well-known member
Hello all,

My name is Don Isbell, Jr.

I have not been in prepress or printing for about a year now (I am now a Forex trader, Don Isbell, Jr. | LinkedIn), but was looking at an Excel document that I made years ago, and converted to Apple Numbers.

Background:

I've kept up with GRACoL since its beta stage, and although this is old stuff, it is and will be relevant in the future as time passes. I figure for many the Excel doc and understanding the graphs may be new, and helpful, so I am posting it here.

Understanding the graph:

INDEPENDENT OF PAPER DENSITY, there are CURVES (named Neutral Print Density Curve, or NPDC, that Don Hutcheson, www.hutchcolor.com, who also chaired GRACoL, and introduced NPDC to the community).

After seeing that SWOP separations could be printed without color managing CMYK, on coated (GRACoL2006_Coated1v2) or uncoated (Beta Uncoated 2009), and appearance between SWOP and GRACoL separations when printed on GRACoL, plus U.S. and Europe appearance was so close (within a couple percent), I was satisfied with my research.

Also, through experience I honored embedded RGB profiles, and used sRGB IEC61966-2.1 profile for RGB images received that has no ICC profile embedded, and had no color problems

Bottom line, I was able to easily implement GRACoL by first getting within LAB tolerances for solid C-M-Y-K-CM-CY-MY using an Eye-One with no filtration, then easily using the graph/the DENSITIES WITHOUT PAPER to GET my TARGETS, and getting TO those ON PRESS with a densitometer SET to give readings SUBTRACTING paper.

Consequently, this math is SO precise that it shows how the official ICC profiles FOR EACH PAPER TYPE could be tweaked to better conform to the NPDC for that particular paper type and density range that the paper has (in fact, most color "problems" come down to coated papers can hold higher densities and result in brighter colors than is possible on uncoated paper). COMMON PROBLEM: MISUNDERSTANDING BY PRINTER AND/OR CUSTOMER OF WHAT IS ACHIEVABLE ON UNCOATED PAPERS AND THEY MAY NEED TO USE COATED PAPER AND NOT UNCOATED TO GET TO THEIR COLOR.

This graph and the target densities at 25, 50, and 75%, with VISUAL way that these ICC profiles interact with graph of GRAY DENSITY is basically one tool that can be used to not only understand color and printing, but can be used to correct printing too.

You can get the original Excel document (in Excel format) at:
COMPARE NPDCs - DON HUTCHESON FORMULA.xls - 4shared.com - online file sharing and storage - download
COMPARE NPDCs 2009.xls - 4shared.com - online file sharing and storage - download
TVI 2009-ADOBE GRACOL TO GRACOL.xls - 4shared.com - online file sharing and storage - download
TVI 2009R-ADOBEGRACOL TO GRACOL.xls - 4shared.com - online file sharing and storage - download

There are others I made, but I can't find them, and they are superfluous.

Thanks goes to Don Hutcheson for making this available freely to the community, so that we can get to ISO standards in a more precise way, even more precise than ISO defines :) Thanks to Don for doing what he could to get us on the same page. I am just a lover of color, and tested and verified for myself and the community what Don was putting forth. I like it a lot. I could be a color consultant, but would rather trade. I hope these documents help you, like Don did, and like I have always tried to do on here when I participated - given freely - and I just love math, so checked his math and see the great benefit of G7 process/graphs.

You'll also see that I use TVI (tone value increase aka dot gain) to compare Adobe and GRACoL ICC profiles using math from color scientist Bruce Lindbloom, www.brucelindbloom.com. These are ONLY VALID for comparison of TVI from two papers with these characteristics:
Printed solids and paper color with very close LAB values between the two papers.

I just like TVI (I'm old school), but see it also is not necessary with the NPDC graphs. So it's here FOR TEACHING/COMPARISON PURPOSES ONLY.

Kind regards,

Don
 
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J

Well-known member
Have a consultant create a print methodology and what you get is a methodology that only a consultant can implement. :p

J
 

disbellj

Well-known member
Are you saying can't implement this? OK. I found it quite easy myself. Do you have questions?

Kind regards,

Don

BTW, I'm no consultant, just said with my knowledge of color all around, I could be one. 15 years was enough for me in prepress and color. Don't want to be in the industry myself, but still have friends I made in the industry and an understanding of print process from beginning to end. Have a more fulfilling career for me now IMHO. Just wanted to share stuff I consider valuable from my previos career. Maybe it's only valuable to me. BTW, on a press, you get to solid densities you need to reach LAB target (yes, it's possible, I did it), you move just the 50% on plate per NPDC chart, and rest falls into place on press. On an inkjet printer, just use GRACoL as source for CMYK sent to printer, sRGB for source on RGB sent to printer, and convert to printer profile as destination, and you're done. Using the Adobe North American General Purpose defaults is efficient. Sorry if I made this sound difficult.

Happy New Year.

Have a consultant create a print methodology and what you get is a methodology that only a consultant can implement. :p

J
 
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gordo

Well-known member
Are you saying can't implement this? OK. I found it quite easy myself. Do you have questions?

I have some questions.
But first an observation.
Dot gain is not a print production target. Tone reproduction is. i.e. it does not matter what dot gain occurs as long as final presswork tone reproduction aligns with the industry standard.

1) Is there an ISO specification for tone reproduction? ISO 12647 is very unclear on this point. Can you provide insight?

2) How does the NPDC tone curve compare with a tone reproduction curve compared with ISO 12647. I.e. when a press is set up according to G7 what does the tone reproduction curve look like?

3) Do you achieve grey balance if you simply follow ISO 12647 vs G7? AFAIK this has not been tested.

4) Since G7 only deals with gray balance, not color, has its premise that grey balance/NPDC, results in a common appearance across different print methods ever been formally tested? AFAIK the answer is no.

best, gordo

BTW several vendors including Heidelberg, 3M, and Creo, and others, all had/have grey balancing software.
 
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D

Deleted member 16349

Guest
1) Is there an ISO specification for tone reproduction? ISO 12647 is very unclear on this point. Can you provide insight?

.

Gordon,

This paper might be related. As I understand it, conformance to ISO is not so good. Maybe I am not reading the paper properly but that is what it implies to me.

http://cias.rit.edu/~gravure/bob/pdf/picrm201108.pdf

There is also another paper, not published yet on Robert Chung's RIT site that seems to specifically refer to the G7 data. That might be of interest when it finally is provided there.

See: Bob Chung

It is a nice idea to have standards or specifications or methods but in the end if a large group of printers can not meet them, there is something wrong.

As you know, I think it is due to capability issues which are not being addressed.
 
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disbellj

Well-known member
gordo,

How's it going my friend? Long time.

This is my understanding, perception and implementation of freely available math in G7 beta original documentation, as well as updates up to end of 2010, and freely available math on the internet at a few different sources that helped me implement it, in essence building my own software that is like IDEAlink Curve. We have targets, we have tolerances, so if we have Excel, willing to put in some time, then we can build what we need. Thing is, it took me some time to get all that together and implement, so for others I ended up saying that the IDEAlink Curve software was worth buying, and that I didn't want to cause conflict by making my own version available publicly basically. Using the graphs will get you there without my automation as far as NPDC. But the first part is important and must not be overlooked.

In a way, I see what you're saying about dot gain. But that is only part of the picture. Allow me to try and simplify by an example.

Let's say we have a tent to put up. We have the tent, four stakes, and a pole for the center that makes the whole thing stand up straight. We must have all parts for it to work, right? Right.

Tent = Laid out flat = same dot response on plate as in file, or in other words 50 in file comes out to 50 on plate.
Four stakes = Four primary solid COLOR (LAB). Get C, M, Y, & K . This is the first part that must not be overlooked.
Center pole = Gray tone scale response curve. What gray is wanted on press for K or CMY. What makes the whole thing "stand up". It's definitive. Not arbitrary in any sense.

ISO 12647-2 lacks, where ICC color management does not. With an ICC profile, you have an EXACT target.

When Europe came out with ICC profile ISO Coated, the primaries were not right, blue was purple on conversion from RGB to CMYK due to the software made to make the profile.

Europe updated to ISO Coated v2. GRACoL uses exact same four primary CMYK solid LAB targets as ISO Coated v2 (and same secondary CM,MY,CY overprints). So U.S. and Europe are same on solids. So we all have the stakes in the ground at the right place.

NOW, SINCE THIS IS TRUE, WE CAN USE NPDC OR TVI/DOT GAIN IMHO for next step. Europe uses TVI/DOT GAIN. GRACoL/U.S. uses NPDC (gray tone scale in DENSITY, for all paper types, using one graph which I've attached. In the Excel documents, you will see input printed LAB values for grayscale. The readings can come from PhotoShop using official ICC profile and Absolute Colorimetric Intent in color settings and reading Lab values in palette. The readings can also come from a GRACoL 7 proof. The readings can also come from a printed GARCoL 7 piece on press.

After the readings are obtained in LAB, the L* is converted to density using math. Then paper is subtracted, and finally the value is plotted on NPDC graph. Because of the "steps" in Excel, you also have the opportunity to bypass LAB, and input density values with paper and let program subtract paper and plot the result on graph, -OR- bypass LAB and density with paper input, obtain readings with densitometer set to subtracting paper.

Now with the NPDC graph, we have definitive targets. Funny thing is, difference between TVI Europe and NPDC U.S. is a "big" as a couple precent. Almost indistinguishable.

I would highly recommend deleting values from column named "PLOT ON NPDC GRAPH" for those printing conditions you don't want to see, and compare e.g. ISO coated v2 and GRACoL2006_Coated1v2, to see the difference in NPDC, and how close U.S. and Europe is. You can not save the Eccel document, and open again and compare another paper type, etc.

Like I said, I do have my own version of IDEAlink Curve that I built from G7 How-To documentation and freely given math in that document, on Don's website, but because of all the hours that went into me building it, I fully understand the price charged for the software, so recommend it to others for easy implementation of G7 for press. I myself, to automate the NPDC graph, had to find math for bezier curves and implement that, after finding and implementing math from most recent update to G7 that gives custom target values for solids and overprints - with new aim values dependent on paper.

Also, as far as others having gray-balancing software, unless you have a paper where the SWOP separations that prepress receives from customers has too high Total Ink Limit (too much ink for paper type), there is no reason to even touch the CMYK in the file. Everyone used old SWOP as their target when making these new printing conditions. It's all basically the same sep on different papers, with TIL in software only for papers who can't take the 300 TIL in the default SWOP profile.

Kind regards,

Don


I have some questions.
But first an observation.
Dot gain is not a print production target. Tone reproduction is. i.e. it does not matter what dot gain occurs as long as final presswork tone reproduction aligns with the industry standard.

1) Is there an ISO specification for tone reproduction? ISO 12647 is very unclear on this point. Can you provide insight?

2) How does the NPDC tone curve compare with a tone reproduction curve compared with ISO 12647. I.e. when a press is set up according to G7 what does the tone reproduction curve look like?

3) Do you achieve grey balance if you simply follow ISO 12647 vs G7? AFAIK this has not been tested.

4) Since G7 only deals with gray balance, not color, has its premise that grey balance/NPDC, results in a common appearance across different print methods ever been formally tested? AFAIK the answer is no.

best, gordo

BTW several vendors including Heidelberg, 3M, and Creo, and others, all had/have grey balancing software.
 
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gordo

Well-known member
Thanks Don for the additional information, however, you did not answer my questions.
Unfortunately Don's math - e.g. NPDC ND = IF(SiCoY > 0, LOG10(100/SiCoY), 1000) - is beyond me.

best, gordo
 

gordo

Well-known member
[snop]
It is a nice idea to have standards or specifications or methods but in the end if a large group of printers can not meet them, there is something wrong.

Before you can try and meet them you have to understand them. IMHO, they are so poorly written that I don't think the average printer is able to understand them. Also, some methods, and core underlying principles are not based on any actual scientific testing. It is very often a faith-based manufacturing process.

best, gordo
 
D

Deleted member 16349

Guest
It is very often a faith-based manufacturing process.

best, gordo

Amen and hallelujah!
Pass the CTP (collection to plate) and your printing sins will be forgiven and have faith that the customer will pay.
 

disbellj

Well-known member
Well, I use a microwave, drive a car, and use all kinds of things that I don't know how they work. So to USE this, it's OK if you don't understand the underlying math.

To know how color works though, you must educate yourself on properties of light - where color comes from, work that was done many years ago dealing with Lab, standard observer, etc., etc..- OR- you can have a mathematician make it easy for you.

When you use a spectrophotometer, you don't have to know math. You know that getting gray you need to deal with L* channel and not a* and b* channels, which should both be as close to 0 to get gray.

When you have IDEAlink Curve you don't have to know math. You want to BUILD what I've built? You must get some understanding of what it is you are doing (what IS the process you are implementing? I had to do that and wanted to do that to make sure it wasn't far from what we were printing, and actually was an improvement. The answer was yes on both accounts, so made sense to move to GRACoL 7 via my software I had built for verification and education purposes.

I would say if it's beyond your head, think of the solids needing APPEARANCE matched, then grays needing matched, then the rest falls into place, which it does and I know not from only theory but from implementation experience. Then 3/C density does tell you exactly which channel needs moved in C, M, or Y on press to get that channel to be equal gray with the others. I guess it comes down to education. Erik I respect but highly disagree with since he has yet to try and understand what I know, yet a chiller was all we needed other than a well maintained old 628 press to not only reach GRACoL, but hit every job within tolerance every day, day in and day out with little makeready time (50 sheets?). The tolerances are given for each 25, 50, and 75 by the specification.

I didn't invent it. I had questions and found answers through research. I proved to myself it works though. Can't prove to anyone else it works without basically giving away the final G7 calculator I built, which would make IDEAlliance upset I'm pretty sure. I give away for free what they charge money for because I built my own and want to? Hey the math was free, and I built it, so I can give it away. But it would kill IDEAlliance consultancy business. It would actually help people see how easy it is though in implementing once you have the software built. It's simple PASS/FAIL feedback. You are hitting the specification or not. No ambiguity about it. And if you understand Lab as the G7 documentation instructs, then you can either on the computer in Adobe programs set to Absolute Colorimetric and using correct output profile or on press change CMYK until Lab targets are hit or in tolerance for the paper type.

Printers are not meeting specification because they are cheap and don't want to spent a dime on color (what makes the tent stand up aka its their business to know color), yet can spend thousands when a press breaks. It's called bad priorities. My ex-boss after their business closed, called me to get new printer he worked at to GRACoL 7. I said I wouldn't do it for free since I was on unemployment. I never heard back from him. Let's say there is a reason I got out of the industry. Willful ignorance and being treated like what I said was a problem when what I had talked about gave them no color problems. Just like everything else. When the crap hits the fan, you are needed and they see you actually doing something. But when everything is running smooth, it must be by accident and couldn't have possibly been engineered/implemented that way so that you don't have problems <sarc>.

I had to bring the printer I worked for kicking and screaming (no, basically they saw no benefit until they were asked by a customer to do it, and I was ready because of my research, and was able to implement IN SPITE of their WILLFUL IGNORANCE of the subject matter). One bad run by the pressman who didn't use the SIMPLE instructions on a job (the thing didn't even look right, I knew it was going to be rejected, but he ran it anyways, and I wasn't the boss, so what could I say? Well, that one job was my years salary, so they had to let me go, and closed the company a week later. But hey, spending a lot less and obeying the simple instructions were too much. I say you get what you deserve when you don't care and you go out of business due to this. Who paid the price? I did. The one that implemented the specification that would have saved that company were it used on that particular job and the job not be ran by an emotional pressman that didn't care that day.

As far as your questions, I talked about dot gain and:
1. How the standard is not specific enough where the specification ICC profiles made from the standard characterization data (think press fingerprint) IS the proof in the pudding, and is not ambiguous in ANY way.
2. Look at the provided NPDC graphs to see the curve and to match that curve. Use the Excel sheets provided free by me to use Lab or density to do this yourself. You don't have to know math equation to see that what is input (your printing condition if you want) is not matching the specification, and exactly where in the tone scale.
3. Yes it has been tested. The result is called ISO Coated v2 ICC profile, and GRACoL2006_Coated1v2 ICC profile. Kodak has a solution that is most listed on the swop website as getting to #1 (coated aka GRACoL 7), and I used that solution to print proofs that I literally could not get wrong. The whole proofing system locked me in to the right proofs, and gave me no control, which because we were printing to specifications, didn't want prepress to have control in the proofing software (was and is not necessary. Just check match by Lab printed numbers once a week is all prepress has to do for proofer. For plates, it checks 50 dot. In Adobe software it uses the defaults. Since it is SO simple, I figured there would be no need for me. Is there many prepress jobs available? I handled the whole department by myself for 8 years, so it only takes one good person that can handle everything in prepress.

Kind regards,

Don


Thanks Don for the additional information, however, you did not answer my questions.
Unfortunately Don's math - e.g. NPDC ND = IF(SiCoY > 0, LOG10(100/SiCoY), 1000) - is beyond me.

best, gordo
 

disbellj

Well-known member
You are the people that should be trusted and you don't even know what you are doing. You can't debate because you are clueless on COLOR.

Is this NOT printplanet.com? Learn, teach, debate? Yeah, and you "experts" are saying this is faith-based? This is NUMBERS. Nothing more. Sorry I'm over the experts heads even after being off a year. I guess we know (why I forgot I don't know) why people are having color problems. You don't know and won't even try to understand the process, won't spend a dime to find out, or even spend some time reading the FREE documentation, yet expect good results. Sorry, this is why you have problems printing if you do, and why I had none but got laid off because of someone else who, like it seems the majority in this industry, claim they know what they are doing, but can't do it and can't even comprehend it, and won't even make sure that e.g. the 25% gray patch reads within .02 density of .22 density. Ridiculous.

Four people voted in my poll. All four have no use for this thread, in the color management section of printplanet, and most printers can't seem to hit this. Let's see: No education, no desire to educate, no understanding of color and light, don't care if the booths are 5000K or not, but we want great color. In your dreams maybe LOL. If you can't get good color, connect all the dots in this paragraph and see why.

There's not many people who care as much as I do about their job, printing, or color, and would go out of their way to educate themselves like I did. Sad but true. They'd rather complain than do anything useful like learn something new. This is why I left the industry. Thanks for reminding me guys. The question is: What will YOU do when you are no longer needed because you don't really understand color? And people like me have all gone and don't care to help the industry because it is so apathetic and obstinate (the people working in it makes the industry the way it is) and we are not welcome or appreciated?

Nothing personal guys. Just have had enough of people being willfully ignorant, and go to name-calling because they can't debate the facts. I present the facts and could present more, but why would I give my final G7 calculator at all when what I have given has not been used by even the people that can download it and respond here. You see yellow slots in Excel? That's where your proof or press input data if you want to. The rest is done for you to make this like kindergarten, but all I hear are the excuses. Must be nice to be able to make excuses. I never was able to. I had to make it work or give real reasons to my boss why it wasn't going to work. The only answer I had to give is when a customer wants bright color on uncoated offset paper, they can't because of the paper type, and it came down to unrealistic expectations and lack of education on both the printers, sales (for they have coated and uncoated guides to show approximately what is possible), customer service (again, ignorance), and most prepress couldn't do what I did because most don't stay in prepress as long as I did, and spent as many hours on and off the clock as I did.

Knowledge is power. Stay powerless if you want to. I don't want to.

Kind regards,

Don
 
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D

Deleted member 16349

Guest
You are the people that should be trusted and you don't even know what you are doing. You can't debate because you are clueless on COLOR.

Is this NOT printplanet.com? Learn, teach, debate? Yeah, and you "experts" are saying this is faith-based? This is NUMBERS. Nothing more.

Don, sorry you are getting upset. It is understandable since you feel you have something of value to provide and I am sure you do.

But there are issues that are still valid that others hold to be true.

Colour does not exist in Nature. Colour is not a property of light. Colour is a perception in the mind. All of colour science is an attempt to deal with a psychological perception and attempt to put that in numbers. So back in 1931 there was an attempt to define colour mathematically. It works quite well but it is NOT an exact science mathematically. The math might be precise but the reality of perception is not. There are many reasons why colours are perceived differently than what the mathematical description says the colour should be.

G7 has nothing to do with colour. Don Hutcheson has never claimed G7 controls colours. It only calibrates the gray line of devices. I have also heard him comment in an online presentation that the upper portion of the NPDC is difficult to determine due to the amount of variation in the offset process. To me that says that only 2/3 of the neutral line can be calibrated well.

I have never heard anything from Don Hutcheson that I thought was dishonest or misleading. But I have heard from others comments about the potential of G7 that is just not true.

I don't think the approaches of using G7 or any targets for TVI are the right future methods to help reproduce colour. I don't see them as being mathematically capable methods of providing solutions to colour reproduction. But that is my personal view.

I will also agree that discussing some of these issues on this forum is not much fun, because there will always be view points that are going to be in conflict whether they are valid or not.

You are lucky you found another career path that gives you satisfaction and I hope that continues.
 
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gordo

Well-known member
My goodness Don

First off, I am not an expert. I did attend 5 of the GRACoL press runs when I was a member of the Idealliance. Based on what I saw and what was said/done at the time, I resigned.

Regarding your comment on the poll results:
Four people voted in my poll. All four have no use for this thread, in the color management section of printplanet, and most printers can't seem to hit this. Let's see: No education, no desire to educate, no understanding of color and light, don't care if the booths are 5000K or not, but we want great color. In your dreams maybe LOL. If you can't get good color, connect all the dots in this paragraph and see why.

You draw such strong conclusions from such little evidence. There may be another explanation.

If you remove the tributes to Don Hutcheson and background information your original post contained very little actual information. Maybe that is why you got such a small response. Or maybe because it's New Year's Eve, or it's just a holiday week?

I have not been in prepress or printing for about a year now (I am now a Forex trader, Don Isbell, Jr. | LinkedIn), but was looking at an Excel document that I made years ago, and converted to Apple Numbers.

What are "Apple Numbers"?

INDEPENDENT OF PAPER DENSITY, there are CURVES (named Neutral Print Density Curve, or NPDC,

And what is the significance?

After seeing that SWOP separations could be printed without color managing CMYK, on coated (GRACoL2006_Coated1v2) or uncoated (Beta Uncoated 2009), and appearance between SWOP and GRACoL separations when printed on GRACoL, plus U.S. and Europe appearance was so close (within a couple percent), I was satisfied with my research.

It's hard to understand what you mean. Aren't all separations color managed? So what does: "printed without color managing CMYK" mean? I don't know what you mean by "plus U.S. and Europe appearance was so close (within a couple percent)" "Appearance" is a vague and subjective term. For example, at one of the GRACoL runs that I attended, Don H was admiring how close the appearance of the current press sheet looked to one that had been printed a month ago at another printer. But to my eye, and a few of the others attending - they press sheets appeared quite different.

Also, through experience I honored embedded RGB profiles, and used sRGB IEC61966-2.1 profile for RGB images received that has no ICC profile embedded, and had no color problems

I think that's common practice but worth mentioning again.

Bottom line, I was able to easily implement GRACoL by first getting within LAB tolerances for solid C-M-Y-K-CM-CY-MY using an Eye-One with no filtration, then easily using the graph/the DENSITIES WITHOUT PAPER to GET my TARGETS, and getting TO those ON PRESS with a densitometer SET to give readings SUBTRACTING paper.

Testimonials are nice, even with the YELLING. But they do not contain much information.

Consequently, this math is SO precise that it shows how the official ICC profiles FOR EACH PAPER TYPE could be tweaked to better conform to the NPDC for that particular paper type and density range that the paper has (in fact, most color "problems" come down to coated papers can hold higher densities and result in brighter colors than is possible on uncoated paper).

Math tends to be precise, and yes profiles can be tweaked - with or without NPDC curves.

COMMON PROBLEM: MISUNDERSTANDING BY PRINTER AND/OR CUSTOMER OF WHAT IS ACHIEVABLE ON UNCOATED PAPERS AND THEY MAY NEED TO USE COATED PAPER AND NOT UNCOATED TO GET TO THEIR COLOR.

YELLING again. This is not a technical problem, it is a communications problem which has nothing to do with NPDC curves or G7. In any case, your statement doesn't contain any helpful information.


This graph and the target densities at 25, 50, and 75%, with VISUAL way that these ICC profiles interact with graph of GRAY DENSITY is basically one tool that can be used to not only understand color and printing, but can be used to correct printing too.

Perhaps you could explain how and why this is one tool that can be used to not only understand color and printing, but can be used to correct printing too

There are others I made, but I can't find them, and they are superfluous.

Then why mention it?

I am just a lover of color, and tested and verified for myself and the community what Don was putting forth. I like it a lot.

Perhaps you could share just how to did your tests so that others could verify your conclusions.
 
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gordo

Well-known member
@Don,

Here are my questions and your answers:

G
1) Is there an ISO specification for tone reproduction? ISO 12647 is very unclear on this point. Can you provide insight?

Don
1. How the standard is not specific enough where the specification ICC profiles made from the standard characterization data (think press fingerprint) IS the proof in the pudding, and is not ambiguous in ANY way.

My understanding is that the ISO profiles only contain colorimetric information - not tone values. Also I was hoping that you could explain the tone curves that appear in ISO 12647 since there is no clear explanation in the document itself.

G
2) How does the NPDC tone curve compare with a tone reproduction curve compared with ISO 12647. I.e. when a press is set up according to G7 what does the tone reproduction curve look like?

Don
2. Look at the provided NPDC graphs to see the curve and to match that curve. Use the Excel sheets provided free by me to use Lab or density to do this yourself. You don't have to know math equation to see that what is input (your printing condition if you want) is not matching the specification, and exactly where in the tone scale.

What I was hoping for is a dot gain or dot area curve to see how different, or similar, the curves from an NPDC set up compares (when base hues are both ISO). This should be a simple thing to do, but it was not done at any of the GRACoL 7 press runs that I attended, and is information that does not seem to be available. If, for example they are the same, or within a few % then the NPDC may be an unneeded complication.

G
3) Do you achieve grey balance if you simply follow ISO 12647 vs G7? AFAIK this has not been tested.
Don
3. Yes it has been tested. The result is called ISO Coated v2 ICC profile, and GRACoL2006_Coated1v2 ICC profile.

Those are not tests. Those profiles are the result of measuring press sheets that AFAIK were not printed using G7. AFAIK, they were based on the premise that ISO is based on (as noted in the publication: linear film-imaged plates). If that's the case (or those were the tests) then ipso facto G7 is a redundant complication.

G
4) Since G7 only deals with gray balance, not color, has its premise that grey balance/NPDC, results in a common appearance across different print methods ever been formally tested? AFAIK the answer is no.

I don't think you answered that question.

What I'm trying to get at is that when specifications and methodologies are developed they need to be related to existing specifications and methodologies and be clearly and unambiguously communicated to the intended audience in a way that they can be practically applied in a typical production environment.
They should also be based on sound, published research.
Otherwise there is confusion and lack of adoption.

A good teacher should not blame the student when the pedagogy is flawed.

best, gordo
 
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disbellj

Well-known member
gordo,

Don Hutcheson nor anyone else is going to help yuou. Sorry. You have to be open-minded. Bruce Lindbloom is a color scientist that midified the Murray-Davies formula and you can use TVI to compare in the Excel documents I provided if you actually looked.

The NPDC graphs are density minus paper. Do you know density? Then a gray tone curve of density can't help you? If your density doesn't match, you ar wrong. Simple enough for me. I made mine match, and guess what? Stuff worked like was said to work, day in, day out.

TONE CURVE = NPDC.

Sorry that you consider that yelling. I use capitals when I want to point something out. It seems if there are capitals in a sentence, it makes you not understand? And as far as methodolofgy, if you attended 5 meetings and I didn't attend one, yet I got it and you didn't, what am I to say other than I did want to understand and wouldn't stop until I did.

As far as explaining to you, I use LAB color. That is the color I need to match. Conversion problems are in the Color Management Module, which is part of the program that makes the ICC profile, and why standard ICC profiles use dby everyone is needed. Nothing else means much to me except for the fact that CMYK target swatches, with default SWOP profile assigned, and Relative Colorimetric Intent are practically the exact same as the NPDC, ISO Coated v2, and I can know exactly what I'm geting on press before I print one thing, and can color correct printed LAB and CMYK values while in CMYK color mode like I said. I can tell you if a color can or cannot be obtained on a printing condition/paper type, can match someone's proof (came up with my own instructions on how to do it almost perfectly match). If this is worth nothing, then gaining knowledge is worth nothing.

I can say that G7 gives targets. If I tell you the targets for solid inks APPEARANCE (YES LAB IS APPEARANCE, AND YES LIGHTING HAS SOMETHING TO DO WITH GETTING THE CORRECT COLOR, THAT IS WHY SPECTROS OUTPUT A CERTAIN DEGREE OF LIGHT).

You have a program you can buy, or you can learn to "roll your own". I like "rolling my own". I like learning.

TVI can only be used with same paper LAB and solid printed C,M,Y,K printed values. Otherwise, TVI falls short. NPDC doesn't. Make a GRACoL proof. Measure the Lab values. If your printed results don't match the Lab values of the proof, then you need something on press to be done.

I got to go visit with my wife. She's upset that I've taken this time to do what I'm doing. I don't blame her. What I am saying is using terms anyone studying G7 should know. If not, then you have moer to learn I guess.

I have answered your questions. If you don't see the answers, re-read until you do.

Kind regards and Happy New Year.

Cya,

Don

P.S. G7 WAS this simple: Get 7 solids to within tolerances given using LAB. Get gray balance within tolerances using density. The reason for the difference at the higher end is because My density to hit LAB numbers may result in different SOLID density than the graph shows. When this happens, you split difference between nearest NPDC lines from 100 down to 50%. The last addendum to G7 added complexity to the solid targets for a reason: To have PAPER DEPENDENT solid target values and PAPER DEPENDENT gray balance values. I added the needed math to my program to implement this. But you don't have my program, so either you DON'T allow for PAPER DEPENDENT solids and grayscale like G7 NOW calls for, use normal target values and tolerances, -OR- buy training and a program that allows you to not only use the device, but you'll learn WHY hopefully that you are using this device and not doing the math by hand. It HAS been made simple. Education will cost you time and money. And if you think knowledge costs, see how much more ignorance of this simple process costs you in the long run. Of course if you need even MORE exact color, then you will be set up to use official ICC profile and color correct and get correct LAB values in PhotoShop before printing a thing and know it will look like what you expect or if it is unachievable given the paper type or because the color was out-of-gamut. Out-of-gamut mapping happens using the ICC profile. IF you all want the same blues across the board, you MUST use the same official ICC profile like Europe does across the board. Otherwise, you'll have differences. At the end, if Total Ink Limit is too high for paper type to be printed on, ONLY THEN use your own custom ICC profile to convert to different GRACoL profile with less Total Ink Limit. I do wish the industry the best. That's why I came back here to share. I didn't have to. I do have another career I am happy in now, that took years of failure before success. No matter what you choose to do in life, if you don't want to be part of the 90%+ business failure rate, you'll CHOOSE to get educated on that particular subject as much as possible without making excuses that never get you anywhere, I would think.

BTW, since both ISO Coated v2 and GRACoL2006_Coated1v2 ARE BOTH ISO12647-2 compliant, uses Bruce Lindbloom's short TVI calculator to just change 50% if you want and smooth the curve. This is same math that gives dot gain in a spectrophotometer. -OR- use G7 and GRACoL profile, and graph and don't pay a dime. Either way it don't matter to me. If you can hit a GRACoL proof within tolerances (and yes G7 can be used to verify the proof - do you actually think I took the vendor's word for it? No), then you're good to go.
 
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J

Well-known member
@Don

Sorry that you consider that (using all caps) yelling. I use capitals when I want to point something out. It seems if there are capitals in a sentence, it makes you not understand?

For your edification (click on link in brackets to see the original web page):

( All caps - Wikipedia, the free encyclopedia )
"With the advent of the internet, all caps in messages became closely identified with "shouting" or attention-seeking behaviour and is considered very rude. As a result, netiquette generally discourages the use of all caps when posting messages online. While all caps can be used as an alternative to bolding for a single word or phrase, to express emphasis, repeated use of all caps can be considered "shouting" or irritating."

( Netiquette - Wikipedia, the free encyclopedia )
"Another rule is to avoid typing in all caps or grossly enlarging script for emphasis, which is considered to be the equivalent of shouting or yelling."

( Why should you stay away from all capital letters online )
"Why should you stay away from all capital letters online?
Answer: Using all capital letters online is often considered to be the equivalent of yelling."

Using all caps the way that you do has been considered the equivalent of yelling pretty much since day one of the internet and www. So, it's not just gordo that has an issue with how you craft your posts.

J
 

disbellj

Well-known member
J,

I give a load of content and all you reply is about caps. How can I come back to such a masterpiece of non-related-to-topic-at-hand work you've put together???

Like I said, stay powerless if you want to. If how I'm saying what I'm saying is more important than what I'm saying, go ahead and miss the important points entirely. That's up to you.

BTW, this will be the last time I respond to you unless you keep on the topic at hand. I have no inclination for fluff. The material I presented is all practical. Don't spend a dime. But if none of you can read the instructions on the graph and implement them, then you have no hope if you will not spend money even after not doing something simple as following instructions PRINTED ON THE GRAPHS (yes, that is important info. I don't give a rat's ass what anybody thinks of it. If you read MY posts, I CAPITALIZE IMPORTANT INFO so that it can STAND OUT. If capitalization hurts your eyes, you are more than welcome to copy and paste to a text editor and make everything lowercase if that would take your focus off the capitalization and put your focus on the issue at hand.

There is no other reason for me to reply beyond this if the topic is not replied to with something of value to the topic at hand.

Kind regards,

Don
 
All those CAPS are Killen Me.....Oh why wont this thread go away !!!:confused:

I know Ive seen this all before on another forum........oh God let it end now !!

Too painful to relive all of that stupidity again !
 

maas

Well-known member
Lets get this interesting discussion back on topic, as a printer i am intrested in how you implemented this i.e. what target did you run what SID etc
 

disbellj

Well-known member
Lets get this interesting discussion back on topic, as a printer i am intrested in how you implemented this i.e. what target did you run what SID etc

maas,

The solid ink density you use for house densities is the density you have when getting 7 solids' Lab values within tolerance of GRACoL-supplied target values (C,M,Y,K,CM,MY,CY). Before the process, I correct for paper error based on math given in addendum to get modified solid target Lab values.

Once Lab target values are reached within tolerance, then I write down those densities and they are the house densities to use for that paper type. Then I use NPDC graph's printed instructions and graphs themselves to correct plate curves at 50% (if needed) and then smooth plate curves. If magenta and yellow are not gray, you can use GrayFinder to move M and Y 50 slightly to make gray. To verify, I use spectrodensitometer reading density without paper, all channels, and make sure that the CMYK are all within tolerance when scanning 25, 50, and 75% K and CMY gray patches. Don't need it automated like I did it, so I will not show pics of this part of the process. Just follow instructions on graphs.

In attached pictures you will find a GRACoL certified proof verified as being within tolerances. You will also find Beta 2009 Uncoated proof being verified that it is also within tolerances. This same Excel document I made I used for easily verifying press sheets also. Note: Use spectro e.g. Eye-One, and make sure your spectro does NOT have UV filtration.

Thank you maas for asking the only relevant question on this thread. The rest of the hucksters just wanted to cause trouble. That's just sad. Thank you for getting down to what really matters and asking the one important question, which is: How can I do it? Hope you can now.

And thank for doing so with some respect. Got you a long way with me. And I say thank you for the respect that you gave, that is due me. Just being willing to learn and not do like the others and make fun of and act childish, which gets one nowhere with me.

Also, if you find what I've given here valuable, please vote the thread up, instead of voting it down like the close-minded people so far have that only been here as an irritation and not added anything meaningful to the discussion.

Kind regards,

Don
 

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