Impact of New Developments of Colour Science on Imaging Technology

Yesterday afternoon, at the Stanford Center for Image Systems Engineering, Dr. Joyce Farrell hosted Prof. M. Ronnier Luo for an update on the latest activities at the International Commission on Illumination (CIE), of which he is the Vice-President. He focussed on the aspects relevant to imaging.

Division 7, terminology, has been disbanded because it has finished its work. The e-ILV can be accessed at this link.

There is a new CIE 2006 physiologically based observer model with XYZ functions transformed from the CIE (2006) LMS functions. These functions are linear transformations of the cone fundamentals of Stockman and Sharpe, the 10º LMS fundamental colour matching functions. In the plot below, you can see the 2º XYZ CMFs transformed from the CIE (2006) LMS cone fundamentals. Note the different shapes around 450 nm compared to the 1931 and 1964 observer models.

The new model is a pipeline in whose stages the age-related parameters can be set. The 10º LMS functions are corrected for the absorption of the ocular media and the macular pigment, and take into account the optical densities of the cone visual pigments, all for a 10° viewing field, yielding the low-density absorbance functions of these pigments. Using these low-density absorbance functions one can derive, taking into account the absorption of the ocular media and the macula, and taking into account the densities of the visual pigments for a 2° viewing field, the 2° cone fundamentals.

There is also a new luminous efficiency function V(λ), which has changed mostly in the blue region.

There are new scales for whiteness and blackness, which corresponds to those in the NCS system. They are based on the comprehensive CAM16 appearance model. Considering a hue leaf of CIELAB in cylindrical coordinates, the south–east ↘ diagonal scale is whiteness–depth and the north–east ↗ is blackness–vividness. These new scales are particularly useful in imaging for adjusting complexion. The skin colors of Asian and Caucasian people vary along the whiteness–depth scale and those of African people vary along the blackness–vividness scale.

Next, Ronnier explained the new color rendering index (CRI) that works also for LED light sources. He also presented a very compelling demonstration of the apparatus used to develop the standard. The new color rendering index is called CRI 2010 and IESNA-TM40. It is based on the measurement of 99 test samples.

I was a little disappointed that the new CRI is still based on colorimetry and not on spectral data. Using colorimetry is an analytical process and having a much larger number of samples helps. However, it does not allow a full characterization of a light source, as we learned many years ago with the tri-band fluorescent lamps. They use less energy, but at the cost of quality.

In this case, I am not too much of a fan of the energy reduction because in practice when you reduce the cost of running a light, people will just deploy more lights and in the end you do not save energy. This is so in consumer applications and does not hold for industrial applications.

Our environment is not made out of BICRA tiles and usually, we are not in aperture mode. We perceive complex images and the light from a set of spot lamps modulates our ambient. While in the case of OLED or fluorescent lamps we might have diffuse light, with LEDs and conventional halogen spot lamps we have more of a set of directed sources with a rapid fall-off.

The rooms in my house are painted in a fusion Italian and Japanese style. The colors are vivid (Italian style), but the paints have a very peaked spectrum so the color is modulated by the illumination (Japanese style). We use older high-quality LED sources with two different green phosphors (the additional one is based on Europium), which we dim. The visual effect is similar to candlelight, except for the correlated color temperature (CCT).

From my experience, I think that a CRI model should include the difference between the spectral distributions of the light source and the reference illuminant. I would also like to have two different reference distributions, A for mood light and D for work light. For thousands of years, we have evolved performing work in daylight and relaxing in blackbody radiator light from fires, oil lamps, and candles. When we want to be in a cozy mood, we pull out the candles, which is also common in upscale restaurants. Candles are more expensive and dangerous than LEDs in houses built from flammable materials.

Should the new CRI also have a provision for the blue hour? Ronnier concluded his presentation stating that the new research topic is tunable white.

The Talented Silicon Valley

The Silicon Valley is not an institution, which tend to be rigid. There have been several attempts to clone the Silicon Valley as an institution, for example, Sophia Antipolis in France and Tsukuba Science City in Japan, but they have not been successful, at least as compared to the impact on society that the Silicon Valley has.

The Silicon Valley is a biotope, which is relentlessly evolving. If you want an economic force like the Silicon Valley, you have to create a habitat for your own ecological system.

If we look at Silicon Valley's evolution, it started with first class educational institutions like Stanford University (est. 1891, motto "die Luft der Freiheit weht" freely following videtis illam spirare libertatis auram) and UC Berkeley (est. 1868, motto "fiat lux"), available capital, and intrapreneurial professors like Frederick Terman (1900–1982), who is credited (with William Shockley) with being the father of Silicon Valley. Terman's doctoral advisor was Vannevar Bush and his notable students included Russell and Sigurd Varian and the HP triad William Hewlett, David Packard and Bernard M. Oliver.

People are the living beings in the Silicon Valley biotope. The brightest minds are attracted and nurtured. Attraction is not accomplished with money, but the recognition and grooming of talent, where people are selected only on the basis of their ability to create insanely great products and are nurtured to fulfill their intellectual potential. In the Silicon Valley, people do not try to predict the future: they have the passion for building it.

Nurturing takes place through an intellectual climate where ideas can flow freely and people see each others as challenging colleagues rather than enemies, even when they are competitors. The open flow of ideas happens through myriad conferences, seminars, meet-ups, dojos and incubators, and even cafes. For example, adjacent to the Samsung R&D building is the famous Hacker Dojo, on the site of HP's first building (Redwood Building on 395 Page Mill Road) is the AOL incubator, and on University Avenue SAP has transformed the New Varsity Theater into Hana Haus.

For an individual, it might not be a tragedy when they are employed below their intellectual potential. The ability to accomplish tasks much faster than their co-workers will yield some freedom and allow for less supervision of their work. However, the intelligent people will be missing in important functions in a company. The society as a whole develops a problem when less intelligent people have to step into senior management positions. Fulfilled potential is called talent, and the Silicon Valley is good at developing talent through mentoring.

Last but not least, this open intellectual climate and talent development make any work very productive and efficient, because when you need to know something, you know whom to ask. You do not have to spend days googling the Internet for an answer that may be incorrect. You get your answer immediately— maybe when it is complex, at the cost of a coffee or a beer.

This is life in the biotope. A characteristic of the ecosystem has always been its rapid evolution. During the cold war and the quest to outbrain the Russians, high-risk research was possible because the government agencies paid cost plus and it was not necessary to worry about commercializing products for the consumer market. When world politics changed, institutions like SRI, IBM Almaden, Xerox PARC, SLAC, HP Labs and NASA Ames eclipsed, but the brains wandered down the road to new institutions, taking with them expired patents and deep knowledge. In the Silicon Valley, the talent is preserved.

While in Rochester the scientists who invented digital photography were lost to humanity when Eastman Kodak faltered and then faded, their colleagues at HP Labs just modified their commute from Palo Alto to Cupertino and are still working on the iPhone camera and imaging system. Few know that Siri was born at SRI and is now evolving at Nuance in the skilled hands of PARC alumni. Maybe, Google could start a self-driving car project due to the available engineers who built navigation systems for submarines.

In fact, the less than thousand scientists who have worked at PARC in its first 20 years, have created the largest pot of wealth in Silicon Valley, as documented by Henry Chesbrough, the executive director of the Center for Open Innovation at the Haas School of Business at UC Berkeley. A beautiful example of ecological brain recycling! The Silicon Valley is a biotope that promotes talent.

Update: a related article just appeared in the HBR: Renaissance Florence Was a Better Model for Innovation than Silicon Valley Is [paywall]

The Fourth Industrial Revolution

In the last couple of decades we have been ambulating in a buzzword fog, with terms that started from the erudite ubiquitous computing to the folksy data mining. Then the buzzwords became increasingly silly with cloud, virtualization, big data, data lakes, social networks, mobility, internet of things, and the like.

Something is going on, but in this buzzword fog it can be difficult to discern what is really happening. Starting tomorrow in Davos and Klosters, the World Economic Forum plans to shine some light on this cacophony and elucidate the current technological events.

First and foremost, a new term to replace the buzzword fog: The Fourth Industrial Revolution. The First Industrial Revolution used water and steam power to mechanize production. The Second used electric power to create mass production. The Third used electronics and information technology to automate production. Now a Fourth Industrial Revolution is building on the Third, the digital revolution that has been occurring since the middle of the last century. It is characterized by a fusion of technologies that is blurring the lines between the physical, digital, and biological spheres.

The inexorable shift from simple digitization (the Third Industrial Revolution) to innovation based on combinations of technologies (the Fourth Industrial Revolution) is forcing companies to reexamine the way they do business. The bottom line, however, is the same: everybody needs to understand their changing environment, challenge the assumptions of their operating teams, and relentlessly and continuously innovate.

The important here is not to be a Luddite and to keep learning. Like our great-grandparents had to learn manufacturing car engines instead of buggy whips, we have to learn aggregating information, services, and tools to produce more efficient tools for increasing the efficiency of society. As always, not everything is rosy—for example, at the upcoming Super Bowl event here in the Valley, the FBI is fearing a biohazard delivered by drone swarms flying over the Santa Clara stadium—but we have to stay focused and determined.

We must develop a comprehensive and globally shared view of how technology is affecting our lives and reshaping our economic, social, cultural, and human environments. The World Economic Forum annual meeting starting tomorrow will shine some light and let us see what we should learn and where we should go next.

The nights are still blue

A few years ago (20 September 2012 to be exact), we had written about our blue nights. We still did not get used to them, but we let the rhododendrons outside the picture window grow all the way to the roof.

Yesterday, I was catching up on my reading and I came across the interesting article LED light pollution: Can we save energy and save the night? by Mark Crawford in the January 2016 issue of SPIE Professional. When we buy light bulbs for the home, we look at the spectral distribution of the light they emit and buy models that have natural spectra. Crawford reports that LEDs designed for street lighting are optimized differently and have typically a correlated color temperature of 6500ºK and are dominated by a narrow, short-wavelength emission band together with a broader long-wavelength emission band.

This results in excessive light pollution, as illustrated in the figure below. This image of Milan was acquired after the transition to LED technology in the downtown area. The illumination levels appear to be similar or even brighter in the city than the suburbs, and the amount of blue light is now much higher, which suggests a greater impact on the ability to see the stars, human health and the environment. Since the European Space Agency’s NightPod device was installed on the ISS in 2012, astronauts have been taking systematic night images. It incorporates a motorized tripod that compensates for the station’s speed and the motion of the Earth below. Before that motion could blur images even though astronauts compensated with high-speed films and manual tracking. This NASA/ESA image was taken by Samantha Cristoforetti.

Do we really need so much street light at night? When I was a kid, all establishments had to close before midnight and half an hour later the street lighting would go off, until six o'clock in the morning. It does not have to be that drastic, but I do not think our lives would be any different if the street lights would be dimmed to well under 0.25 lux after midnight. We no longer walk, and all vehicles have headlights by law. For the few pedestrian a faint light is more than enough because we adapt to the light level: the pupils dilate and eventually we switch to scotopic vision. When I was a kid and walked home after the street lights were off, I could see extremely well at full Moon, which is just 0.25 lux. When the Moon is not full, you just walk slower and enjoy the Milky Way.

I am not a Luddite. In Palo Alto, the heart of the Silicon Valley, in the Barron Park neighborhood everybody turns off the porch lights at night, and these people are the cream of the digerati. The neighborhood's park is called Bol Park, after Stanford physicist and research associate Cornelis Bol, the inventor of the high-intensity mercury vapor lamp.