Color Calibration of Satellite Cameras

For those of you who do not know me, my name is Paul Matheson. I work with Nathan and Giordano at HP Labs. My background is in commercial print and I consider myself to be a printer. Hopefully I will be able to add something of value to this hallowed blog - if not, I am sure Nathan and Giordano will make me pay for several rounds at the Nuthouse so at least they'll get something of value out of me.

Several days ago I stumbled across this article explaining how satellite cameras are calibrated. It reminded me of Nathan's post about a revolutionary white reflectance standard for metrology - curiously enough, the post was entitled "Revolutionary White Reflectance Standard for Metrology." The original blog post is gone but I was able to find a couple of links to the blog, one of which included some of the text.

Unlike Nathan's post, Lake Tuz really is used for calibration. I knew that many satellites have cameras, but it never occurred to me that they would need calibrating or that image sensors in orbit degrade significantly. The thing that I enjoy most about this article is the fact that some smart person(s) figured out how to use unique geographic features as reflectance standards.

Science is cool.

Image of Lake Tuz from the Image Science and Analysis Laboratory, NASA-Johnson Space Center. "The Gateway to Astronaut Photography of Earth."

Is teamwork good or bad?

Actually, in today's issue the Science magazine editors phrased it differently: "Two Heads Are Better Than One," but then you have to watch for the caveat. They summarize the research conducted in London and Aarhus as follows: "When two people peer into the distance and try to figure out if a faint number is a three or an eight, classical signal detection theory states that the joint decision can only be as good as that of the person with higher visual acuity. Bahrami et al. propose that a discussion not only of what each person perceives but also of the degree of confidence in those assignments can improve the overall sensitivity of the decision. Using a traditional contrast-detection task, they showed that, when the individuals did not differ too much in their powers of visual discrimination, collective decision-making significantly improved sensitivity. The model offered here formalizes debates held since the Enlightenment about whether collective thinking can outperform that of elite individuals."

Like being there in Hi-rez and Color

1. Cincinnati waterfront captured on daguerreotype plates c.1848. Restored by conservators at George Eastman House in Rochester, New York. What was unexpected is the resolution of these daguerreotypes. The panoramic set could be blown up to 170 by 20 feet without losing clarity—a digital camera would require 140,000 megapixels per frame to match it. Since the exposure time was on the order of minutes, anything that moved significantly was not imaged. Particularly interesting is seeking out the "ghosts" of slower moving people and horse-drawn buggies moving along the line of sight of the camera.
   
2. Photographic survey of the Russian Empire c.1910. Taken by Sergei Mikhailovich Prokudin-Gorskii under the auspices of Tsar Nicholas II before the outbreak of WW1 and the Russian Revolution. This is not (Ted) Turnerization of black and white photographs but a "digichromatographic" restoration of the original color plates. I highly recommend comparing with the more recent photographic views available in the accompanying Google Map links.
   

Stunning!

AIC Newsletter 2010

The AIC Newsletter 2010 is now available online at http://www.aic-colour.org/news/news23-10.pdf.

Glad not to be on the stake

Last month President Nicolas Sarkozy of France, addressing the International Conference on High Energy Physics in Paris, declared (click on "more" for official translations):

Certainement on ne peut qu'être saisi de vertige lorsqu'on essaie seulement d'imaginer les questions auxquelles vous vous attaquez ! Il fut un temps où elles relevaient de la métaphysique. Elle nous semble loin cette époque où les découvertes de Giordano Bruno lui valurent le bûcher et celles de Galilée, — mieux traité !— la prison. Estimez-vous heureux de vivre à votre époque ! La science est une démarche, je le sais, fragile et vous devez être défendus, vous les scientifiques, vous devez être défendus contre l'obscurantisme, contre le fanatisme, contre le refus des faits et contre le mépris de la vérité. Ces risques sont actuels, ils sont de tous temps et de toutes époques.

and

La science est un édifice qui doit être complet : il n'y a pas d'applications sans recherche fondamentale, il n'y a pas de saut qualitatif dans le progrès des connaissances en dehors de la recherche fondamentale et de ses découvertes. Ce n'est pas en prétendant améliorer la bougie qu'on a découvert l'électricité.

CPS: what are they?

To scientists formed throughout the Cold War, the term cybernetics leaves a funny taste in the mouth. During the Cold War, the West had astronauts while Eastern Europe had cosmonauts, and we had computer science while they had cybernetics. The term—from Greek kubernētēs ‘steersman,’ from kubernan ‘to steer’—used in this context goes back to 1948, when the American mathematician Norbert Wiener published the book Cybernetics or Control and Communication in the Animal and the Machine.