G-Seven Calc v2.1

[kewlbigdan]

G-Seven Calc v2.1
by KewlBigDan

THIS SYSTEM IS NOT CERTIFIED BY IDEALLIANCE and will never be. Seriously $7000??

This Excel Document is FREE. You must of course own the Excel (2007/2010) application. I am not sure it works on MACs, other Excel versions or other Excel document emulators.

I have used this software 100's of times for RIP curve calculations, verification, and G7 certifications and it gets us through each time with no problems.

I have to say it is not a polished system, and you have to have your data in a certain format for it to work but if you follow the instructions it should get you very close to where you want to be without spending $2000 for a professional app. Saying that, Purchasing any of the G7 Certified Systems would always be better if you want guaranteed results, but if your on a budget, or work for a cheap company and your tired of Fangraphs...this will work.

The 1 MACRO only imports (copy paste) the data from another excel file (your saved P2P25 data) so if you want to manually do that disable them, it still calculates fine.

My company put me in charge of getting us re-certified G7 Master Printer and I had no clue what G7 entailed. they also didnt want to purchase the Curve2 software and wanted me to just use the Fangraph method for 10 presses, 5 substrates, and mulitple runs. So rather than sit for 4 weeks manually calculating fangraphs for 150 P2P25s, (ok dont roll your eyes, I said I didnt know what I was doing, was just following orders).
So I searched on internet for another solution. There didnt seem to be any application other than the $2000+ applications out there. So I started reading, searching, experimenting. I started in Filemaker Pro, but decided to move to Excel as it works for all the calculations.
I got my hands on the G7 How To 2008.pdf which unlike the G7 How To 2009, Has most of the formulas required to get the results. This problem came translating these formulas into something workable in Excel. As the Formulas deal mostly with LAB, it took another month of searching mathimatical conversion formulas to be able to convrt Densities into *L and back again, and working out the correct NPDC curve data.
First I worked on the brute force method of just inputing the values from the Fangraph and doing a look-up, lots of data entry but after useing this method for testing I stumbled across how to do all the math to dynamically (learning polynomial equations in the process) calculate the curve for any SID. This was a boon as it opened up alot of other factors that then became possible.
So by this stage I could target teh NPDC curve dead on with a simple Correcttred RIP curve but the Grayscale *a *b formulas still evaded me.
So embedded in all the calculations are 5 different calculations by radio button for calculating the Grayscale. I tested each extensively but none really worked correctly. Maybe I was blind or dumb but I could not figure how to have excel find the Gray target off the P2P25 and then calculate the desired grayscale RIP curves.
6 months went by, I gave up. Then one day I was reading some obscure manuscript from a professor to his students about something and it all clicked. (The paper had nothing to do with G7 and was dated in the 70's if I recall, why I was reading it I have no idea, it was one of those moments when i typed some weird thing in the search engine and it popped up). Anyways, I rewrote, which I hate to do, hence the still embedded 5 grayscale calculations, the grayscale calculations with this new understanding and the results were spot on.
Since I wasn't G7 anything by this stage, I still had to use a G7 Expert company to verify and submit all our G7 Master Printer data and I submitted our data for analysts and the results from their Curve2 software matched exactly my results, down to the graphs depictions.

 

[Deleted member 16349]

Maybe something of interest. New G7 curve 3.

CHROMiX and HutchColor announces Curve3 is shipping - WhatTheyThink

Personally I think the whole G7 is a waste and a distraction from what should be done, but if that is what people want, then that is what they will have to do.

 

[kewlbigdan]

I am not in this for profit.
Curve3 costs about $2500.
This is free and gets you the same place.
Just not with the bells and whistles.
But then I guess a Fangraph gets you there as well.

Anyways as I said, I am posting this for those that can't afford, or dont want to pay the $2000+ for a G7 app. I developed it for my personal use and a vendor thought it was nifty and wanted a copy so I decided to Post it.

 

[chromix]

Actually, Curve3 costs $1199 (as did Curve2). It's 1/2 that for upgrading from an earlier version.

There are extras that can bring the price up but that is for simulating the second press run.

It sounds like you spent a lot more of your company's money (in time) writing your own solution but as you said, it's what they wanted. G7 is intended to be an open solution so people can build their own tools if they want. It sounds like you did, and that's cool.

regards,

Steve

 

[kewlbigdan]

Steve, I did it completely on my own time. When I put in for G7 Training, it was denied because the G7 Master Printing company (please dont laugh to hard here) saw no benefit from it, so I did that on my own pocket as well.
So now G7 Expert that is on MY resume, and this Excel spreadsheet is mine to give away, and I don't have to feel guilty when I decide to move to another job.
I always think if you can afford it, to use a professional software solution, unfortunately I know there are many guys out there working the Fangraph because the Boss will not fork out the $1500 for software. This is to help those people, not compete against the PRofessionals

 

[MGB_LE]

Maybe something of interest. New G7 curve 3.

CHROMiX and HutchColor announces Curve3 is shipping - WhatTheyThink

Personally I think the whole G7 is a waste and a distraction from what should be done, but if that is what people want, then that is what they will have to do.

Erik, I'm interested in your opinion. If G7 is a waste and distraction, what would you suggest people do instead? We haven't gone G7, in part because of cost, but if there are alternatives, I'm all ears.

 

[Deleted member 16349]

Erik, I'm interested in your opinion. If G7 is a waste and distraction, what would you suggest people do instead? We haven't gone G7, in part because of cost, but if there are alternatives, I'm all ears.

MGB_LE, G7 does not ensure colour now. It is mainly a calibration method to ensure that different devices print the same gray line. G7 is probably slightly better than the traditional dot gain compensation methods that have been traditionally done because it seems to be an attempt to align the whole printed colour gamut to the L line.

When I said "what should be done" this was not directed at users but at developers of technology. At this time, there are no easy to use and predictable colour management methods. Just ask Frank Romano. He recently made a rant about this on an Enfocus seminar.

Sorry I can't be of more help.

 

[Stephen Marsh]

When I said "what should be done" this was not directed at users but at developers of technology. At this time, there are no easy to use and predictable colour management methods.

I think that users of Kodak Prinergy should look into their bundled ColorFlow software, although to get the most from this under advertised tool they would need to upgrade to the Pro version to create their own profiles and devicelinks. Kodak ColorFlow is simple to use and it is designed to seamlessly and effortlessly provide not only colour management of a single device using curves, ICC profiles or devicelinks - but colour relationship management between multiple devices.

Just ask Frank Romano. He recently made a rant about this on an Enfocus seminar.

I made the mistake of downloading that webinar, after listening to half of it I decided that I had better things to do with my time, such as watching one of the other virtual safari recordings.


Stephen Marsh

 

[Deleted member 16349]

I decided that I had better things to do with my time, such as watching one of the other virtual safari recordings.


Stephen Marsh

If you are happy with the present situation and it gives consultants and suppliers such as yourself lots of work to bill customers, then I can not argue with your opinion.

My view is that if the whole process worked so well, one would get predictable results and not need lots of effort to get things to work.

So are you saying that now that Frank Romano is making some negative comments, that he is not worth listening to?

 

[Stephen Marsh]

If you are happy with the present situation and it gives consultants and suppliers such as yourself lots of work to bill customers, then I can not argue with your opinion.

There is always room for improvement, for both vendors and users of vendor’s solutions.

My view is that if the whole process worked so well, one would get predictable results and not need lots of effort to get things to work.

This area is what Prinergy’s ColorFlow is intended to address for the commercial market. From simple/limited “tint ramp” tonal measurements, curves are created. One can align colour between devices using “TVI” or “grey balance” methods. The software works this out and generates the curves, not the end user. One can also measure spectral characterisation charts and create ICC profiles and devicelink profiles to manage colour, above and beyond curves. ColorFlow uses the principle of a “Primary Colour Output” (PCO), which is the main output device, with multiple “Secondary Colour Outputs” (SCO) which are linked to the PCO. If there is a change in the PCO, the software automatically calculates, modifies and updates all linked SCO devices to match (without needing to make new measurements, although one can and should do so if one is not happy with the results). The whole system has been designed to work as seamlessly as possible, while also being simple in design so that users don’t need to be colour management specialists. No solution is perfect, however ColorFlow goes a long way to “make colour management simple and seamless”. ColorFlow is not available as a stand alone product, it is only available to Prinergy users, with the base version being a free component and paid update versions available to create ICC and devicelink profiles and to create “ink saver” profiles.

So are you saying that now that Frank Romano is making some negative comments, that he is not worth listening to?

Not at all, I am saying what I said. ;] What I said was that after listening to half of his rant, I decided that I had made a mistake. I did download his rant after all, knowing that it was a rant and that it was not intended for educational purposes (although I was hoping for something “more” from it, which is why I gave up on it). Frank and his opinions are respected and liked for many reasons. I like a good rant as much as the next person - however after listening to half of the webinar, I decided that learning something was better use of my limited time and energy. Others may feel different, as is their right. Who knows, at some future point in time, I may revisit the downloaded recording when I have the mental fortitude to do so or perhaps if I am feeling masochistic or in need of “light entertainment”.


Stephen Marsh

 

[Deleted member 16349]

There is always room for improvement, for both vendors and users of vendor’s solutions.


Not at all, I am saying what I said. ;] What I said was that after listening to half of his rant, I decided that I had made a mistake. I did download his rant after all, knowing that it was a rant and that it was not intended for educational purposes (although I was hoping for something “more” from it, which is why I gave up on it). Frank and his opinions are respected and liked for many reasons. I like a good rant as much as the next person - however after listening to half of the webinar, I decided that learning something was better use of my limited time and energy.


Stephen Marsh

I agree with you that the rant did not provide any solutions to the problems. Hard to listen to it if one feels there are solutions or wants to find out about solutions.

The point of my referring to his rant was to highlight the issue about the mess that exists in the colour management environment and that someone who is very respected feels that way. That was the only value of the rant.

 

[Justin M]

KewlBigDan,

I am currently in the process of trying to calibrate my HP Indigo 3550 to G7 standards. I downloaded your excel calculator and it seems really robust. I printed out the p2p25x target with no color management and linear curves and measured that. I then input it into the excel calculator to create the curves. I typed up the values except with Indigo curves they have decimals whereas a 50% dot is recorded as .50. Anyways, I created the custom curves but the image still has a magenta tint to it. And the gray circle test, the circle looks too magenta and doesn't match the outside. Any ideas on what I could be doing wrong here?

Thanks,

Justin

 

[Deleted member 16349]

KewlBigDan,

I am currently in the process of trying to calibrate my HP Indigo 3550 to G7 standards. I downloaded your excel calculator and it seems really robust. I printed out the p2p25x target with no color management and linear curves and measured that. I then input it into the excel calculator to create the curves. I typed up the values except with Indigo curves they have decimals whereas a 50% dot is recorded as .50. Anyways, I created the custom curves but the image still has a magenta tint to it. And the gray circle test, the circle looks too magenta and doesn't match the outside. Any ideas on what I could be doing wrong here?

Thanks,

Justin

The G7 method does not ensure accurate colour. It is meant to calibrate the device so the gray line is correct. That is basically it. This has been stated by the originator of G7, Don Hutcheson, right from the start of its introduction.

Others may imply that it ensures accurate colour but so far I have never read that Don Hutcheson has ever claimed that.

So you can be doing the right thing with respect to G7 but you may need additional colour management applications to get the colour right.

 

[Justin M]

Erik,

Correct, G7 doesn't control the saturation of colors. I'm saying, it looks like even after the new curves, the gray balance is still off. Even though the HR, HC, and SC patches are very close for K and CMY patches. Even the circle test where the inside is CMY and the outside is K only should be really close after only G7 curves to my knowledge.

Are you saying that it's possible for the grays to be still off after new curves?

 

[Deleted member 16349]

Erik,

Correct, G7 doesn't control the saturation of colors. I'm saying, it looks like even after the new curves, the gray balance is still off. Even though the HR, HC, and SC patches are very close for K and CMY patches. Even the circle test where the inside is CMY and the outside is K only should be really close after only G7 curves to my knowledge.

Are you saying that it's possible for the grays to be still off after new curves?

Not totally sure what you mean. If you are talking about the gray balance in an image, that I would say is colour and G7 does not ensure that it will be correct.

As a side note, I seem to remember that the patches of CMY gray and K did not have the same target colour in the G7 method. Maybe this has changed but I thought it was strange that they wanted it to be different.

Someone who is experienced in the application of G7 hopefully can help you better. I just know it does not ensure colour accuracy on its own. Not just saturation but also hue.