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

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

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tmiller_iluvprinting

Well-known member
how 'bout a group hug!

how 'bout a group hug!

Having bantered and debated with Mr. Isbell in the past I know what most of you are going through. Don arrived at a place where any printer worth there salt arrives, matching press sheets and proofs. The journey was just longer for Don. My employer has been super supportive, G7 Training, IDEAlliance Curve Software, Spot-On! Software, Eye1's, DTP 70's just to name some of the tools that my employer has flipped the bill for. Don didn't have the luxury of working with some of the best, Mr. Hutcheson, Mr. Hunter, Mr. Bohnen, Mr. Wyse, just to name a few that have guided my path on this colorful journey. Don chose not to seek the advice of Dr. Rodriguez, Mr. Pritchard, or Mr. Eddington, but rather spend countless hours pondering and tweeking his own method of press and proof inter-agreement, while we were at happy hours, ball games, by the pool, etc. So does this make Don wrong? Not really! Doesn't necessarily make him right either, but God knows that if he spent as much time as he did, I'll just give him the benefit of the doubt. God, I love printing, this stuff is great!

Regards,
Todd
 

tmiller_iluvprinting

Well-known member
I inadvertently omitted Mr. Apollo from my who's who list of color management stars. Sorry Rich! And to everyone else who has helped me on my way, thank you!
Regards,
Todd
 

disbellj

Well-known member
Todd,

I spent hours automating the UP, OVER, DOWN, which are MANUAL steps printed on the graph, along with the 1st step of Lab solids. I didn't reinvent anything. My company would not pay for IDEACurve software, but I was being asked to do the impossible (get there without even a spectro, which I could have done the solid matching by eye, but really needed the EyeOne), so I made my own IDEALink Curve software. Made mistakes from using too many points. But EVERYTHING was taken from the G7 documentation from the outset. Was this my choice? Yes on where I got the info. No on wanting to build the software. I wanted to keep my job and have spent my career doing the impossible for the unappreciative. But I can tell you what I learned in Excel led to doing Excel stuff in programming MQL4, so I'm a trader, good at Excel, and MQL4. Three things I wasn't just 5 years ago. It's cool. I like being able to code my ideas and not pay a programmer to do it.

Well, looks like my previos post got deleted. But anyways, I love color too. I loved making pizzas as my first job. Do your best no matter what you do and you won't have regrets about it.

Kind regards,

Don
 
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tmiller_iluvprinting

Well-known member
....@Gordo

....@Gordo

Test Targets Volume 10, a RIT publication has an interesting paper written comparing TVI and G7 Calibration Methods by simulation. The publication also has other papers that explore OBA's and their effect on color, as well as other relevant topics. Well worth the $29(US) cost, and a good read if you are interested.
Regards,
Todd
 

disbellj

Well-known member
Also got to say this one other thing Todd. As far as I am concerned, there was never a time when our proofs and press sheets didn't match.

Old way = Took fingerprint of how press printed linear film made into plates and put on press, and used that ICC profile in proofing. Problem = Different target at every printer for same paper type.

New way = Instead of fingerprinting press, MAKE press conform to ISO 12647-2 standard via GRACoL specification, using G7 method. Problem in old way now resolved. All pointing at same target.

I complained for years until we had a standard ICC profile like Europe had long before us. One profile we could all use = a common target. I tried to share my findings in Printing Across Borders. In fact, when you don't have a U.S. profile to go with for the paper type because it hasn't been made yet in U.S., use one from Europe.

So just for the record, I always matched press sheets. Way before G7. But there was no standard appearance for all printing customers to design to. So as an artist at heart, I always saw their point of view and tried to do the little I could to just get an ICC profile for coated paper #1, so they could know without printing a thing what it would look like in PhotoShop or InDesign.

What took me longer to get there than other people was I couldn't verify anything with a proofing EyeOne that contained UV filtration, because the target readings were for non-UV filtration spectros. So it took me years to get my boss to see any merit, he borrowed an Eye-One from XRite to "test", and during that short time, I had the device I needed to set up the press. Then checking each press sheet was able to be done with newly bought spectrodensitometer without spectro function (I kid you not).

So yeah I had a hard road, and don't recommend it. Buying some education and software/hardware makes it so much easier it's ridiculous not to, unless someone just gets a kick off of driving the people in their company crazy doing everything except what is needed to get to ISO 12647-2. If you can't verify it, you may be within tolerances, but don't know. Not knowing is a problem. But that's what you get when you have a printer that sees no problem, so why fix it. In my case, me being the only one in the building that gave a crap about color pretty much made me crazy, and in the end, the system I put into place G7 with verification, wasn't used, and the company shut down. I ask every company, which way would you go? The hard road, or the easy one? If I EVER had the say so (which I didn't and that's a fundamental problem - THE prepress AND color guy having NO input, VERIFICATION NOT ENFORCED AT PRESS AND BIN DERY), then the company would still be open today. But when the boss doesn't care, it really doesn't matter who else does. My story is proof.

Kind regards,

Don
 
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gordo

Well-known member
Old way = Took fingerprint of how press printed linear film made into plates and put on press, and used that ICC profile in proofing. Problem = Different target at every printer for same paper type.

New way = Instead of fingerprinting press, MAKE press conform to ISO 12647-2 standard via GRACoL specification, using G7 method. Problem in old way now resolved. All pointing at same target.

The old way as you describe it was the method promoted by many print color consultants 10-15 years ago. There are some cases where it makes business sense, but for the majority of printers it was as wrong then as it is now. (There is an explanation here: Quality In Print: Press and proof alignment strategies )

The "new way" as you describe it is actually pretty much the old way. I.e. the specifications in N.A. were input specifications that the printer was required to match. I.e. The certified proof embodied the color target that the printer was required. The problem was that in N.A. there was no consensus as to the primary and secondary hues used to make the certified proof. So one could have a Fujiproof and a Kodak proof both be certified yet display different colors. What GRACoL did was bring awareness of ISO 12647 to N America and make its hue targets the N.A. targets.
Somehow, AFAIK, the Europeans managed to follow ISO 12647 and achieve grey balance despite not having the G7 method (which is not for color but for grey balance). Perhaps someone from Europe could comment on that.

best, gordo
 

disbellj

Well-known member
gordo,

I agree with what you said. But it does come down to an ICC profile. Method you choose what you want to do. Europe uses TVI. ISO is a barn door for TVI tolerance. Not specific enough. There were problems in the ICC profile Europe had for conversion. So out-of-gamut mapping is in ICC profile. This is why a standard ICC profile is necessary to get same blues across board. Then if printer needs to do moe GCR on CMYK they receive, so be it.

I provided NPDC and TVI. Plug in ISO Coated v2 and GRACoL2006_Coated1v2 and compare in both calculatorsL TVI (aka Europe) and NPDC (aka U.S.). No matter which you decide to use, since we have ICC profiles, if you hit either one, you are within tolerances.

Although I will not go into more detail on GRACoL and G7 because I have, it should be highly noted that NPDC method was able to be used by many people on different paper types, and get to the natural appearance and make a custom ICC profile where GRACoL has not yet. IMHO NPDC is VERY useful, many paper types can use the same graphs, where TVI falls short if solids and paper between the two are not the exact same. This is what I've seen from my own research. Other than my own research, and what I've given, I can't tell you who has researched this. But I have provided my calculators so that ANYONE can look at and compare both methods, with yellow cells to input data, and graphs for visual verification/comparison.

Kind regards,

Don



The old way as you describe it was the method promoted by many print color consultants 10-15 years ago. There are some cases where it makes business sense, but for the majority of printers it was as wrong then as it is now. (There is an explanation here: Quality In Print: Press and proof alignment strategies )

The "new way" as you describe it is actually pretty much the old way. I.e. the specifications in N.A. were input specifications that the printer was required to match. I.e. The certified proof embodied the color target that the printer was required. The problem was that in N.A. there was no consensus as to the primary and secondary hues used to make the certified proof. So one could have a Fujiproof and a Kodak proof both be certified yet display different colors. What GRACoL did was bring awareness of ISO 12647 to N America and make its hue targets the N.A. targets.
Somehow, AFAIK, the Europeans managed to follow ISO 12647 and achieve grey balance despite not having the G7 method (which is not for color but for grey balance). Perhaps someone from Europe could comment on that.

best, gordo
 

disbellj

Well-known member
raffelj,

That makes my day!

The color/math geek in me enjoyed researching and making and using it :)

Now I get to know it is helping others understand what's in the G7 documentation when seeing the math behind it.

Bruce Lindbloom modified the Murray-Davies formula. It's Obvious Don Hutcheson admires the work freely given by Bruce, since Don has links to Bruce's website on his website in his free area. But I too find that Don's approach is simple and good.

I just used G7 documentation, again freely given on the web, and connected the dots.

The automation I didn't share took the longest of all, required me looking up advanced math on the web, and I find that on press, since I only needed to change the 50% value for each separation, the extra math was just a step too much, and not useful for press. A person can do it easily manually via the instructions on the K and CMY graphs to go "up-over-down" to find new plate values for 50% for each separation.

But the math is all VERY cool to me. I love it, and now see I'm not the only one :)

Kindest regards,

Don


Don,

Thanks very kind of you to share. The color/math geek in my is going to enjoy this very much.
 

Prepper

Well-known member
You are some kind of glutton for punishment! You escaped the zoo and came back for more? :)

There will always be more than one way to achieve anything, well, usually, and coming from where you were, and where I am still, there will always be believers, unbelievers and make-believers.

Ideas can be debated all day long but the proof is in the results, whatever works and works well for someone is what they should stick with.

You helped me a lot when I was struggling on my own to implement G7 and later on we got the software and tools we needed to do it easier.

I'm no expert by any means, but I do know that printing to G7 using GCR has done wonders for our color stability on press and proof to press matches and makeready times, 5 years running now. I keep threatening to throw a job at the press like we used to with just SWOP seps, no curves for TVI or NPDC applied, no GCR, just for laughs and let them remember what it was like struggling to get color match and stability on press.

I think the majority of people who have implemented it successfully have pretty much the same response from what I've seen.

Good luck Don, and don't look back!
 

David Milisock

Well-known member
Reading is fundimental, comprehension is not understandfing.

Reading is fundimental, comprehension is not understandfing.

Bruce Lindbloom is very talented, as a tradesmen for 37 years I find talent is something that's sorely needed.
 

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