Wednesday, January 28, 2015

Fluorescent Whitening Agent µ-conference

I have some good news. I counted 64 authors that will be representedat the 2015 TAGA Annual Technical Conference. We are still making adjustments to the program, but once things settle out I expect there will be 35 papers presented at our conference in Albuquerque. As vice president of papers for the Technical Association of the Graphic Arts, it has been my awesome privilege not only to decide which papers to accept for the conference, but I also got to read the abstracts.

TAGA Annual Conference, March 22 to 25 in Albuquerque

As I reviewed the abstracts over a couple of bottles of Shiraz, I noticed something odd. I mean something other than the fact that I was drooling. There were six abstracts submitted on different aspects of the same topic: Fluorescent Whitening Agents (FWAs). Imagine that! So as VP in charge of papers, I made an executive decision. I declared that TAGA 2015 will have a Secret Agent Micro-Conference on Fluorescent Whitening Agent Metamerism. That's pronounced "SAM-ka-FWAM", in case your wondering. And yes, I am in secret negotiations with a certain well known comic book company about licensing the super hero.

Note: FWAs are also known as Optical Brightening Agents (OBAs), and Secret Agents, but FWA is the more better term cuz it’s more scientifical and all that. 

Just in case you are wondering about FWAs and the new M1 condition, I have done a bit of writing on the subject.

A megacool UV flashlight on three paper stocks (left) and a white LED flashlight (right)

Here is a fabulous preview of the six fabulous papers on FWAs…

In 2014, Bruce Leigh Myers presented at TAGA, telling us that the handful of spectros that he could get his hands on (at RIT) didn't agree with each other as well as one would hope. No flat out shouting matches, but he was disappointed that they formed little cliques.

Later in 2014, he took his FWA test samples on the road to GraphExpo and wandered around, forlornly asking anyone who would listen to measure his samples. His new results will be presented. Will there be close agreement? I have my guess, but I’m not going to share.

Veronika Lovell (from Sun Chemical, with the help of Robert Marcus and Danny C. Rich) took up a similar challenge and looked very closely at three instruments that came from three different manufacturers. She, too, found significant disagreement. She had a hunch about what might be causing the difference and got out her slide rule to test this hypothesis. I can hardly wait to hear her results!!

David Wyble (of Avian Rochester, LLC) heard some people talking about all this “instruments don’t agree very well” stuff. He decided to dig a little deeper, asking some probing and fundamental questions. “Are the requirements specified in ISO 3664 and ISO 13655 adequate for the evaluation of instrument sources? Can the acrylic standards adequately simulate the behavior of the fluorescent compounds in commercial papers? How might physical standards be applied to the instrument profiling process? Can two instruments be adequately aligned either spectrally or colorimetrically?”

The even deeper question that will be answered is whether his co-author (John Seymour) will hold up his end of the deal and actually help out! Of course, we all know that John will take credit for the whole idea regardless.

Of course, measuring color is not the only issue when it comes to FWAs. We must also be able to assess color by eyeball in a standardized way. To do that, you need a standardized lighting with a standardized UV content in a standardized viewing booth. And you also need a way to make sure that your viewing booth really does have the spectral output that is claimed on the wrapper.

Every year, the Printing Industries of America gives out InterTech Technology Awards to recognize new products that are expected to make a difference in the printing industry. Just Normlicht was one of the 2014 recipients, and as such, they get a shot at giving a technical presentation of their technology at TAGA. Eric Dalton, who just happens to work for Just Normlicht, will give us a rousing overview of this instrument that is just another piece of the puzzle when it comes to taming this FWA monster.

How big is this monster, anyway? It’s about time somebody did a study on that! Luckily, somebody did. Changlong Yu did his Master’s Thesis on that topic. Not monsters in general, but one particular monster. Lemme ‘splain.

You print a proof, likely on an inkjet printer onto inkjet proofer paper. You take that proof out to press and try to match it. But you’ve already got one arm tied behind you back. The paper will be different. It’s likely that the FWA content is different. Changlong did a lot of psychometric testing and will report on how much difference is perceptible. You gotta love research that includes psychometric testing.

I dunno… some folks actually want to get paid for print jobs. That’s a concept a little beyond me, but Bob Chung is interested in the practical aspect – the application of Changlong’s research. Bob took the perceptibility difference a step further, and looked at how much of a change in color (due to FWAs) is acceptable. The cool thing is that he comes to a recommendation that is quite simple.

So, between the two previous papers, we got the hard copy proof thing nailed. How about softproofing? Peng Cheng wanted to address this part of the puzzle for his thesis. Peng used substrate corrected colorimetric aims to build profiles, and then did psychometric testing. There it is again… psychometric testing! Yes!

Did anyone notice that I said there were six papers, and then I talked about seven? You can't trust a math guy to count correctly.

All in all, I think we got us here the makings for the best Secret Agent Micro-Conference on Fluorescent Whitening Agent Metamerism since God said "Let there be light". Meet me in the bar afterward and I will teach you the SAM-K-FWAM secret handshake.

Oh I almost forgot. We have 29 other great papers that will be presented!

Wednesday, January 14, 2015

Red mammals

I am soooo embarrassed. I passed along factoid, and it was untrue.

Here's how it all went down. I made a simple statement in my blog post What color are your blue jeans?  The statement was an inconspicuous factoid, shared with my readers at no extra charge:

"By the way, the pigment responsible for gingers is only found in humans. No kidding. I red that on the internet, so it must be true."

Let me tell you, John the Math Guy fans everywhere. There ain't nothing like an egregious lie to bring down the wrath of ... well, I don't want to play into stereotypes of people based on hair color, but there was a fiery furor, I tell you. 

Redheads react to the error in my blog

The first hint of the upcoming storm came as a post on the blog itself. Janneke Duoma had this to say:

"The red haired cannot be anything else but a Human? Eh...and the fox is.....? Not a human that's for sure but I would swear I saw a red glow on that fur. Tssss... Science prooves me wrong?"

Hmmm... she has a point there. Now, my eyes ain't no speck-trow-foe-tomater, but the red hair of a red fox does kinda look like the red hair of some other "foxes" I know. I had to go back to my source. Where did I learn this dubious factoid?

Actually, I lied about that as well. I said that I "red" it on the internet. Clever misspelling, but a lie. I read it in a book by Hazel Rossotti entitled "Colour: Why the World Isn't Grey". Here is where I got the factoid (on page 93): 

"Red human hair, unlike the red hair of any other mammal, is produced by an unusual pigment which contains iron."

Maybe the world isn't gray, but what about my beard?

(Actually, according to the internet, you can see that I quite enjoyed the book.)

The pigment in red hair

So... I need to play fact checker. Is Rossotti's comment correct?

I start with Wikipedia, to identify the pigment in red hair. The Wikipedia entry on red hair says:

"The pigment pheomelanin gives red hair its distinctive color. Red hair has far more of the pigment pheomelanin than it has of the dark pigment eumelanin."

Wikipedia could be wrong, so let's look a little further. The Causes of Color website agrees with Wikipedia, in that pheomelanin is the pigment that is active in human red hair. 

(BTW: When you are done reading my previous 111 blog posts, have a look at the Causes of Color website. Interesting stuff. But in the mean time, it kinda sounds like pheomelanin is the operative agent.)

The best laid pigments of mice and men

So, we have established that the pigment that Ms. Rossotti is referring to is pheomelanin. But clearly she can't be wrong, since John the Math Guy wrote a glowing review of her book, and I read on the internet that he is a sharp guy. So, obviously, that pigment won't be found in any other mammal.

Well, not quite... 

Pheomelanin can be found in mice and in men, as these two scholarly articles will attest.

"It appears that rodents adaptively modulate eumelanin and pheomelanin contents to achieve cryptic coloration in contrasting habitats even at a microscale."

"The color of hair, skin, and eyes in animals mainly depends on the quantity, quality, and distribution of the pigment melanin, which occurs in two types: black to brown eumelanin and yellow to reddish pheomelanin. ... High levels of pheomelanin are found only in yellow to red hairs of mammals and in red feathers of birds."

How about the red foxes that Janneke mentioned?

"In red foxes, the contribution of pheomelanin to the total hair melanin content was twice as large as in the hybrids."

Red fox in my backyard, in 2009

Red foxes, yup. It seems even dogs make use of pheomelanin.

"Labrador Retrievers are a popular breed of dog in many countries. There are three recognised colours, black, chocolate, and yellow, that result from the interplay among genes that direct production and expression of two pigments, eumelanin and pheomelanin, in the fur and skin of the dog."

These labs are happily oblivious to the interplay among genes
that direct production and expression of eumelanin and pheomelanin

Dare I stop now?  Nay!  Pheomelanin is even found in reptiles!!

"Reptiles, supposedly, do not produce pheomelanin pigments. Because this claim is based on rather weak evidence, we measured the shell pheomelanin content in the Hermann’s Tortoise (Eurotestudo boettgeri). In contrast to expectation, we detected a substantial amount of this pigment. Given the recent interest in the adaptive function of melanin-based color traits, our study opens new avenues of research in reptiles."

I hope that you are also excited about these new avenues of research! In case you were wondering (I'm sure you were) ... "the existence of fungal pheomelanin is still under discussion." Well, I guess that gives organic chemists something to talk about while watching reruns of  Chopped.

One more lie exposed

Guess what?  Remember how Ms Rossotti told me that the pigment in red hair contains iron? I found an article on the chemistry of melanins. Now I don't claim to have much knowledge of organic chemistry - other than the tiny amount that I memorized for an organic chem class in high school and promptly forgot. But, I don't see any big "Fe" symbols in the picture below. I think even that was sadly untrue. 


So, so, so many lies. First, I lied about reading that factoid on the internet. Then the factoid turned out to be another lie, since the same pigment is used for red hair in humans, mice, red foxes, and in Hermann's tortoise. And finally, there is the whole claim that the pigment for red hair contains iron.

The tooth fairy, Mighty Mouse, trickle-down economics, and now the whole "people with red hair have a unique pigment" story... The fox has been caught red-handed in a statement lacking truthiness. So many lies that I have been told. Sigh... I am not going to obsess about it. It would only shake my faith in the whole house of cards that is science.

I want to apologize for my participation in the promulgation of that nasty lie about the pigment in red hair. My only defense is that I was just repeating what someone else told me. This gives me but meager comfort. We should all feel just a tiny bit guilty when we pass along stuff that just ain't true. 

Wednesday, January 7, 2015

Whaddya mean 68%? I want 95%!

I opened up an individual serving container of yogurt the other day. You know, the kind of yogurt container that gives yuppies a bad name? Not only was it the fancy "Greek" yogurt, but the kind that uses 5.4 ounces of packaging to give you 5.3 ounces of yogurt? Honestly, I only eat it because my wife buys it at the grocery store.

But I didn't mean for this blog to be about me. The contents of the yogurt container reminded me of a blog post that I have been meaning to write. You see, that yogurt container had only 2.6 ounces of yogurt. Yes, it was half full.

Picture of me, ordering a yuppiegurt

Now, I'm a yogurt-container-half-full kinda guy, but if my wife had opened that container, I am sure she would have immediately been on the phone to the customer service department at Chobani. She would wait on hold for an hour just to give them a piece of her mind. Oh... and she would get a bunch of coupons. What did I do? I smiled, shook my head, and said "sampling and manufacturing tolerances!" Yes, I got the short tail of the Gaussian curve when it came to manufacturing tolerances.

--- Now I'm going to change the subject from the stuff in the package to the package itself ---

This all reminded me of a discussion that I had with my good buddy, Steve Smiley. We were talking about one of our favorite topics - ISO 12647-2. Yes, we can be a couple of wild and crazy guys when you get us wound up. A little beer and a little hot Mexican food, and we're quoting stuff like this: 

The variability of the process colour solids in production is restricted by the following condition. For
at least 68 % of the prints, the colour differences between a production copy and the OK print shall not exceed the pertinent variation tolerances specified in Table 7.

(Table 7, you will recall, has a lot of 4 DE and 5 DE stuff in it.)

Steve has taught me to always check the halftone dot structure before partaking

The last time Steve and I chatted, he told me that the brand owners that he consulted with weren't happy with 68% of the product being within a certain tolerance. They want 90% or even 95% within some tolerance. They know that my wife will be inspecting the labels on the Chobani packages. If just one of them is just a slight bit pale in color, they know that they will be sending yet another packet of free coupons to Milwaukee.

Seriously... while my wife is on a first name basis with the customer support people for almost all the consumer product companies, the real reason that the color of a package is so important is that if a package is a bit off color, then people will pick over it in favor of the brightly colored box. Eventually that off-color package is going back to the factory with its handy fold out pouch between its clam shell blister pack. Just like I found out when I tried stand-up comedy at the Baptist's convention, off-color doesn't sell.

I had a simple answer to Steve's question. I'm sure that I didn't articulate it well, since we were on our third bottle of sriracha sauce by then. It was an application of a blog post I did called "Assessing Color Difference Data". The whole point of this blog is that for distributions of color difference data, there is a simple conversion between the 68th percentile and any of the other percentiles. I copy the table from this remarkably insightful blog post:


It's not obvious from the table, but the conversion is pretty simple. If a color tolerance is stated like this: "68% of production shall be within 5 DE of the target color", then you can convert this to a 95% statement with the following calculation:  (5 DE / 1.224) X 1.840 = 7.52 DE. The first part, dividing by 1.224, converts from a 68th percentile to a 50th percentile. The second part, multiplying by 1.840, converts the 50th percentile DE to a 95th percentile. To put it simply... you multiply by 1.5.

So by my careful and erudite analysis, the following two specifications are equivalent:

"68% of production shall be within 5 DE of the target color"
"95% of production shall be within 7.5 DE of the target color"

If a press run meets the first criteria, then it will pretty well meet the second, and vice-versa. Unless of course, the press has decided to not follow the laws of statistics.

I have intentionally left a topic un-discussed: How do you tell what percentage of the press run was in tolerance? I'm gonna save that thrilling question for my next blog post.