Monthly Archives: November 2009

where do the stars go in the daytime?

Galloway Forest Park in Scotland has picked up an international award as one of the best places for stargazing in the world. The 300sq mile Forestry Commission site has been commended for its dark skies and named one of the best places in the world for stargazing.


So where do the stars go in the daytime? The answer is that they are still there of course. It is a nice reminder that our colour vision is more about contrast than about absolute intensities. With old TV sets when they were switched off the screens were grey; but when they were turned on it would be possible to see some really dark blacks. But the screen cannot emit less light than when it is turned off! So the black looks black because of contrast, not simply because of the amount of light emitted or not emitted.

Against the dark skies of night the stars contrast and appear bright – during the day, the skies are much brighter because of the sun and though the light from the stars is just as intense as it is at night the contrast conditions are very different.


This week I attended IS&T’s 17th Color Imaging Conference in Albuquerque –

Attendance was a little lower than normal (because of the recession) but the quality of the conference was certainly not down on previous years. In fact, it was one of the best CICs for a while. I would recommend the conference to anyone with an interest in digital colour or colour imaging – the next conference will be November 2010 in San Antonio, Texas. The two things I like best about the conference are the content (as usual I came away with several new ideas that I can’t wait to get back and try) and the people. It’s a really friendly bunch of people and a great place to meet all those great colour scientists whose papers and books you’ve read.

Next year I may offer a short course in MATLAB. The short courses are held on the day or two before the conference starts proper.

As for the location – Albuqueque. Well, a little disappointing, to be honest. It’s a place I always wanted to visit. It sounds so exotic but in the end it is about as exotic as Huddersfield. It’s true that Old Town Albuquerque (where the conference was held) is interesting and quite qaint. However, I just walked down Route 66 into the downtown area today and it was disappointing to say the least. I think I saw the future of UK cities today – with the downtown area boarded up and empty and everyone in shopping malls that are 8 miles out of town and only accessible by car.

To read more views about the conference go to twitter and look for #cic17.

See you there next year?

Tokyo blues

East Japan Railway Co. has spent £100,000 fitting out all 29 stations on Tokyo’s central train loop, the Yamanote Line, with the strong bulbs.

The operators believe they will emit a soothing glow, despite the absence of any scientific proof that the method reduces suicides.

Mizuki Takahashi, a therapist involved with the project, said: “We associate the colour with the sky and the sea.

“It has a calming effect on agitated people, or people obsessed with one particular thing, which in this case is committing suicide.”

A total of 68 people threw themselves in front of trains in the 12 months until March, up from 42 in the same period the year before. The lights will be hung at the end of each platform, a spot where people are most likely to jump to their deaths.

blue tokyo










Cryptic coloration

Cryptic coloration is the most common form of camouflage, found to some extent in the majority of species. The simplest way is for an animal to be of a colour similar to its surroundings.


The female Misumena vatiaspider switches her body colour over the course of days depending on the flower where she lurks. This is often cited as an example of cryptic coloration. However, according to a new paper in Proceedings of the Royal Society B, a white spider on a white flower doesn’t catch more prey than a white spider moved to a yellow flower. Nor does a yellow spider on a yellow flower get a colour-coordination bonus. The study may shatter the myth of crypsis by colour matching in crab spiders. For further details see

The colour of the universe

The colour of the universe is …..






Astrophysicists Karl Glazebrook and Ivan Baldry took light measurements from more than 200,000 galaxies, broke them down into their constituent colours and then averaged the colours out to produce a single shade visible to the human eye. The result was beige. See

Staying on the space theme, One week ago, the MESSENGER spacecraft transmitted to Earth the first high-resolution image of Mercury by a spacecraft in over 30 years. MESSENGER’s Wide Angle Camera is equipped with 11 narrow-band color filters, in contrast to the two visible-light filters and one ultraviolet filter that were on Mariner 10’s vidicon camera. By combining images taken through different filters in the visible and infrared, the MESSENGER data allow Mercury to be seen in a variety of high-resolution color views not previously possible. MESSENGER’s eyes can see far beyond the color range of the human eye, and the colors seen in the accompanying image are somewhat different from what a human would see.

The color image was generated by combining three separate images taken through WAC filters sensitive to light in different wavelengths; filters that transmit light with wavelengths of 1000, 700, and 430 nanometers (infrared, far red, and violet, respectively) were placed in the red, green, and blue channels, respectively, to create this image.