さきみだれる = blue light + cryptochrome 2

We scientists have a special way to ruin a poetic or romantic moment. For example, we might be sitting in front of the most powerful sunset, and all that we can think of is Rayleigh scattering and how what we see is just the effect of the fourth power on the frequency factor.

And now another natural phenomenon might be ruined: 咲き乱れる (さきみだれる), for which we do not even have a proper translation — it took a Japanese haiku master to come up with such a concept.

Here is how the editors of Science summarize the paper by Liu et al. from the department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles:

Plants respond to light with a variety of developmental and physiological changes. The receptor for the blue-light wavelengths is cryptochrome. How blue light causes cryptochrome to alter cellular function has been a puzzle. Now, using a yeast two-hybrid screen, Liu et al. have identified a protein from Arabidopsis, CIB1, which, in the presence of blue light, interacts with the cryptochrome. CIB1 and cryptochrome colocalize in the plant cell nucleus, where CIB1 functions as a transcription factor. Together, these proteins bring the input of blue light into the signaling pathways that regulate flowering.

By the way, this cryptochrome mechanism is one of these tricks Nature is using over and over, in us humans too. CIB1, which is short for cryptochrome-interacting basic-helix-loop-helix, appears to affect primarily the amplitude, but not the period, of the circadian rhythm of the FT mRNA expression. Therefore, next time you complain about jet-lag, think the same mechanism also controls floral initiation and more poetically, 咲き乱れる.

Now, if we could only remember how to let a thousand flowers bloom in research labs!

Click this link to access the paper: Photoexcited CRY2 Interacts with CIB1 to Regulate Transcription and Floral Initiation in Arabidopsis.

Transitioning colors: purple

In my post on the ephemerality of color names I wrote that color names can go out of fashion and then the label of a given color is lost. It also happens that a label is persistent, but the color associated with that name changes. Purple is such an example.

Nathan's color thesaurus responds to "porpora" with the color of hexadecimal value b23372, which looks like

However, if we look at this old mosaic in San Vitale in Ravenna, we see a different color for the same label "porpora":

What happened?

From Phoenician times the purple colorant was extracted from molluscs living in the coast of present day Lebanon and Israel. It was a rare colorant, hence used only for textiles destined to the rich and powerful. In fact, in 1464 Pope Paul II decreed that cardinals have to wear purple.

By coincidence this was the time the Byzantine empire crumbled and in the Ottoman empire the Purple industry in the Eastern Mediterranean disappeared. Hence, the tailors had to switch to a red colorant, but the papal decree cast the label "purple" into concrete.

If today you visit a religious clothing store, when you ask for Purple you will get a red cape, as shown below. In this case, Italian crowdsourcing returns Purple more to the original color, but not quite.

This is a big problem for restorers. As you might have seen in the Sixtine Chapel or Leonardo's Last Supper, today's restorers are very aggressive in restoring the original colors, instead of just freshening up the old paint in its current state.

One way to figure out the original colors is to study the master's notebooks and find textual descriptions of the colors. Unfortunately, for a given label, the colors transition, especially today when all paints care constantly reformulated to make them less toxic.

Anyway, these color transitions is exactly why Prof. Giovanni Brini in Torino has compiled his comprehensive color name dictionary. It is intended for restorers who have to pin-point the color for a given name at a given date.

A wimp's 40th birthday

Industry analysts generally equate modern personal computing with the GUI, or graphical user interface. Therefore, March 1992 is generally seen as the birth of the PC, namely the release date of Windows 3.1.

There is then another group of analysts that then counters the GUI was really invented on 24 January 1984 when the Macintosh was released. Of course others then claim the GUI is older than that when Smalltalk with its WIMP paradigm was invented at Xerox PARC.

Actually, the WIMP paradigm is even older than PARC. The PC was really invented concomitantly with the mainframe, and the main person behind it was "Lick" Licklider. You can read up the PC's history in M. Mitchell Waldrop's "The Dream Machine."

Anyway, the acronym is WIMP, which stands for windows, icons, mice, and pointing. That goes back to 40 years ago.

It the PC's history was linear, today we would use them to solve partial differential equations. The basic idea was time sharing, later called adaptive computing and today called cloud computing. Not a reason to spend money on an iPhone, Blackberry, or Netbook.

The paradigm shift occurred in San Francisco on 9 December 1968 at 1 p.m. at the ACM conference, when Doug Engelbart demonstrated his On-Line System or NLS. It was about augmenting human intellect, and in a single demo (a.k.a. The Mother of All Demos) he introduced concepts like windows, hypertext, mice, cording keyboard, collaborative software (groupware), video chatting, networking, and more to a stunned crowd still using punched cards.

The celebrations are this afternoon at Stanford in the Memorial Auditorium.

Happy Birthday, WIMP!

The ephemerality of names

From the paper mentioned in my post of 2 December we know that color categorization is probably mediated by language, which is what is meant by the statement "a form of categorical perception that is lexically influenced." The next problem is how to deal with the ephemerality of language.

Languages are in constant evolution (well, maybe with the exception on French, where bytes are still called octets). For example, in Japanese the katakana script that was originally used for bureaucratic and male writing, has been repurposed to write words of foreign origin — and how many foreign words there are! Look at something as common as milk, which used to be 牛乳 (ぎゅうにゅう, gyuunyuu) but now is simply ミルク (miruku).

Closer to home, consider late ETH Prof. Heinrich Zollinger's work ca. 1975, where he collected color names from TKD chemistry students:

The ordinate is the frequency of occurrence for the name of the Munsell hue in the abscissa. Note how オレンジ (orenji) is more frequent than 橙 (ダイダイ, daidai) and ピンク (pinku) is more frequent than 桃色 (ももいろ, momoiro).

Maybe the change of the Japanese language is a bit extreme, but English is also changing fast, especially for words related to fashion, like color names. Look for example at the names in Coloroid hue 20 I showed last week:

Did you know the color name Arsigont? Did you know the difference between Pompeian yellow and Indian orange?

This is not a problem of the Coloroid system. Consult any color name compilation older than a few years, and you will find names that look unfamiliar. For example, a decade ago teal was all the rage in Palo Alto and all home decoration stores were selling many items in this color. Today, people hardly remember its appearance.

So, how do we deal with the ephemerality of language? Obviously a printed leather-bound collector's edition of a color dictionary is not the ticket. The ephemerality of a blog tool post is more like it. But color names are very hard to collect, we cannot start from scratch every few months.

This is why in the Italian version of his color thesaurus, Nathan included a mechanism to rate the pairing of the color name with the displayed color. As names fade, they get rated worse and by using the rating in the creation of the thesaurus, a more contemporary color name will emerge to label that color.

Colored geese

When I did my first steps in image processing, researching new algorithms was not for the faint of heart. First you had to be a maestro programmer (a.k.a. wizard) because to get the algorithm to run with a usable performance on a sub MHz processor with 64K bytes of memory you had to write a paging algorithm to fit it all in memory and code the inner loops in octal code so not to miss any clock cycles and work directly on the barrel shifter. You also had to stick an exception handler at the beginning of the boot loader to catch processor faults and get a chance at debugging your algorithm.

A first quantum leap happened when Photoshop came out, because you could first try out things interactively, then you could write a plug-in with your algorithm.

The next quantum leap happened with MatLab, which contains well programmed image processing libraries that allow you to quickly implement your algorithm expressing it as a linear algebra problem.

A new quantum leap is happening now with Mathematica, which now allows images as parameters, contains an image processing library, and gives you the full power of symbolic computing. Read more about it in this blog post by Theodore Gray. [Click the image to view the movie.]

Many thanks to Don O'Shea for the pointer.

Categorical color perception moves from right to left hemisphere across life span

It feels a very long time ago when in 2003 I was assigned to solve a problem in variable data printing — when colored text is printed on a colored background and the colors are variable, the text may become unreadable. Since each copy is different in a variable data job, manual proofing is not feasible and an algorithm is required.

Conventional colorimetry is of no use, because it deals with color matching — small color differences — not the large color differences to be considered in readability issues. Required to quickly deliver some code, I came up with a heuristic based on ∆E units. Silvia Zuffi and Carla Brambilla of the CNR in Milano-Bicocca have revisited that work and performed genuine research replacing my heuristics.

Once the code was delivered, I implemented a different algorithm more suited to the task. As the research by Zuffi and Brambilla shows, the readability problem can be formulated as a reading speed problem. From Stevan Harnad's work we know that color discrimination is faster for colors in different perceptual color categories than for colors in the same perceptual categories, when their perceptual distance (∆E) is fixed.

The most obvious way to introduce structure in a color space, i.e., to introduce perceptual color categories, is by considering color names. The new problem now is to find a 3-dimensional tiling of a color space. I had the data for Nemcsics's names in the Coloroid system, so I implemented that.

The implementation of the readability solution was then straightforward. I used the lexical distance between the two colors and required at least 2, i.e., there had to be at least a color name between the two color's names.

The solution performed only so-so. In fact, there were a number of issues.

1. The transformation from CIE tristimulus is only published in part and required a lot of experimentation to pin down
2. This transformation is numerically instable, so an industrial-strength implementation that never fails is not trivial and requires skilled programing
3. The tiling does not cover the whole gamut, so it needs to be "stretched"
4. There is no reference in the literature on the origin of the categories and names — did Nemcsics cook them up heuristically?

But the biggest question is: are the color categories mediated by language? Is it legimimate to use color names for a lexical metric? Each time I put up my old color cognition diagram

co-blogger Nathan Moroney always interjects that color categorization may occur much earlier. The paper Categorical perception of color is lateralized to the right hemisphere in infants, but to the left hemisphere in adults in a recent issue of the Proceedings of the National Academy of Sciences comes very close to answer this question.

Franklin et al. take advantage of the difference between the left and the right hemisphere of our brains (let us assume for a moment we are all right-handed and have a normal corpus callosum) that the left hemisphere is geared to encoding categorical or relational information, while the right hemisphere is geared towards encoding metric information.

The linguistic hypothesis in color categorization is that colors are tagged by their category name and the tags are compared, i.e., that language mediates categorical color perception. The question is whether the color categorization is prelinguistic, i.e., whether there is a universally available color categorization and language just makes some minor adjustments, or color categorization is built from scratch after language is available.

Franklin et al. used a group of 21 years old right-handed adults and a group of 21 week old infants and compared their categorical color perception skills, obtaining these results:

(remember the neural axons get crossed in the optical chiasm). Categorical color perception is found in infants; however, the absence of a category effect in the left hemisphere for infants, but the presence of a greater left hemisphere than right hemisphere category effect for adults, suggests that language-driven categorical perception in adults may not build on prelinguistic categorical perception, but that language instead imposes its categories on a left hemisphere that is not categorically prepartitioned.

Their findings therefore suggests that there is a form of categorical perception that is nonlinguistic and right hemisphere based (found in infancy) and a form of categorical perception that is lexically influenced and biased to the left hemisphere (found in adulthood). Categorical color perception is found for both infants and adults, but the contribution of the left hemisphere and right hemisphere to categorical color perception appears to change across our life span.

Our digital presses are for adults, so my approach is valid.

Recycling slideware

In my years at HP I have produced a very large corpus of slideware. The sad part of this is that unlike papers, slides are ephemeral artifacts discarded after a single use. I write sad, because a lot of effort goes into the production of a slide deck, especially in industry, where there are strict design rules and everything has to be "high-concept".

In the past I was posting my formal external presentations in my publications web page, as a link in each conference paper reference. This was useful for people finding my publications using a search engine, but now people use more specialized search tools and then find my publications in the digital libraries of various learned societies in whose conferences the work was presented. These digital libraries do not contain slides because they are informal.

There is a service that allows you to recycle your slides. It is called slideshare and allows you to upload your slides for conversion in to Flash objects that can be embedded. Probably the most logical place to embed your slides is your LinkedIn profile, were people in your social network can discover them, download them, and reuse them.

You can also embed the slides in your blog, like here a presentation I gave in September:

Cognitive Aspects of Color

View SlideShare presentation or Upload your own. (tags: color_names color_dictionary)

As you can see, you can quickly browse the slide deck right here in the blog. If you want to reuse some or all of it, you can click on the title above the slide. This takes you to the slideshare page, from where you can download the presentation.

As you may note, some functionality gets lost in the conversion from PDF to Flash, like the navigation labels in the slide headers. However this is a minor detail. Because the slides are on slideshare's site, you can embed as many slide decks as you want in a post, without burdening your blog platform.

For example, here is my trusty old slide deck on Understanding Color:

Understanding Color

View SlideShare presentation or Upload your own. (tags: color_science short_course)

As you see here, the QuickTime movies are not embedded, but the link on the slides is more convenient anyway, because you can prepare the movies in QuickTime players and show them from there.

Of course, a simple slide deck like this one on MPEG-21 carries over as is:

Introduction to MPEG21

View SlideShare presentation or Upload your own. (tags: mpeg mpeg21)

By the way, each of these slide decks was produced with a different authoring tool. The color cognition deck was produced using the fancy Beamer document class in LaTeX, the introduction to color in the antiquated but robust FrameMaker document preparation system, and the MPEG-21 deck was written in PowerPoint.

The future of electronic paper

The Web site "The Future of Things" has an interesting page on the future of electronic paper. It has interviews with Nick Sheridon of Xerox PARC resp. Gyricon and Till Moor from Siemens. Many photographs show prototypes developed in the laboratories of various companies active in this field. The link is http://thefutureofthings.com/articles/1000/the-future-of-electronic-paper.html.

Pigeons missing in action

It used to be that when traveling you had to bring to your hosts presents from your place of origin. This custom is known in many cultures and words like souvernir or おみやげ (omiyage) have been absorbed in many other languages.

Today this is no longer meaningful, because the concept of exotic has disappeared. This is due to the science of logistics, which has made the transportation of goods so efficient that now you can buy everything everywhere and at the same price.

Despite the miracles of modern logistics, it has a point of failure: the operators follow the instructions of computers, and even if goods are tracked at every step, they can disappear when an unanticipated event occurs.

For example, on September 17 I gave a presentation on color cognition and promised to send a printed copy of Nathan Moroney's color thesaurus and the presentation handout for the asking. When I returned home, I ordered the prints from MagCloud and mailed them to the interested parties.

Unfortunately, the envelopes never arrived. Because the recipients where in different countries, I can be certain that the snafu must have happened before the mail was sorted, i.e., between the mail stop near my cubicle and the United States Postal Service Processing and Distribution Center in San Francisco.

I did stamp the envelopes as air mail. Maybe a confused logistics operator strapped the envelopes on carrier pigeons… Were the carrier pigeon then hijacked in the San Francisco Bay and kidnapped to Eyl?

In fact, most of the time logistics operators do not know what they are doing. They are just trained to blindly and efficiently follow the procedures dictated by the logistics computer. This is one of the tenets of the anorexic company — there are no provisions for the unanticipated or even for incertitude. Immediate action must be taken, regardless of whether it makes sense.

Maybe two countries are a little better off: Japan and Switzerland, where workers are expected to always use their brains when they work (possibly with an exception here in Martigny, where many a brain has become yogurt from boozing Fendant). This is achieved through the concept of the apprenticeship, where future workers are employed as trainees in their future profession while also attending vocational school to develop a theoretical understanding of their chosen profession.

At the Federal Institute of Technology in Lausanne (EPFL) the DUAL-T project in the field of computer-supported collaborative learning has recently delivered to the Centre Professionel du Nord Vaudois (CPNV) this system to train logistics apprentices:

Some smart young people indeed! Should I have carried the envelopes to Martigny and mailed them from here? Not necessarily, because the logistics at SFO or LAX could have lost my suitcases there.

So, if you come across some lost carrier pigeons with a color thesaurus, please energize them and send them along their way…

Social Signal Processing

From Eats Shoots & Leaves by Lynne Tuss we know the importance of punctuation and that occasionally it can be a matter of life and death. However, in some cases punctuation cannot come to our rescue.

Such is the case for social signal processing or SSP. We all know what signal processing is, namely the analysis, interpretation, and manipulation of signals. (Incidentally, in our case the signals of interest are color images.) So is social signal processing a European form of socialized processing of images, like social medicine?

In social signal processing the adjective is not social but social signal — it is about the processing of social signals. What makes this confusing is that many of the researchers in this area are signal processing experts. In view of this, the alternate name of social signals understanding is maybe more appropriate.

SSP is concerned with the machine analysis of social behavior. It is a branch of interactive multimodal information management and studies non-verbal behavioral cues and social behavior. Recently SSPNET, a new Network of Excellence funded under work programme topic ICT-2007.2.2 of the European Commission's Seventh Framework Programme, has been funded.

Just imagine yourself one day sitting in front of a financial advisor to talk about your retirement savings and consulting an application on your smart-phone that can assess if you are talking to a snake in a suit…