Wednesday, March 5, 2008

Cows and Other Hazards of Color Science

By Thor Olson
(Imaging scientist by day, Astrophotographer by night)

Editor's Note:
Thor Olson has captivated audiences at IS&T/SID Color Imaging Conferences with his creative astrophotography. In 1998 he showed stereo images with millions of miles between the “eyes,” in 2002 he showed colors of the deep sky, and last November he explored colorful high dynamic range. Here he describes an encounter with nearer planetary objects.

The Color Imaging Conference is always an inspiration for me, and the 2006 meeting in Scottsdale was especially so. Having just taken Greg Ward's conference tutorial on high dynamic range (HDR) imaging, I was excited about applying it to astrophotography.

A plan was made. Following the conference, I traveled to Monument Valley, a remote corner of Arizona where I could find desert skies to take exposures through my telescope for HDR image stacking.

The weather was clear, cool, and windy, and I found protection on the veranda of the Navaho Tribal Park's visitor center. To gain my night vision I temporarily unscrewed the security floodlights, and then spent a productive evening taking pictures of the night sky. I imaged some of my favorite astrophoto targets at the exposure times I would need to compute an HDR composite. The pleasant challenges of the evening came to a close as I realized how cold I had become. I packed up and started the drive back to my hotel in Kayenta, twenty miles away.

Driving home after a night's observing is always more challenging than the drive out. It is late, or rather, early morning, your blood sugar is at its diurnal lowest, and your usual bedtime was hours ago. If you are like me, you are pumped up from observing the sky on a clear night. Running the defroster at full strength to the windshield, you are in an odd mix of mental and physical states.

The roads are empty, and even though you are not looking directly at them, the blast of your headlights onto the pavement ahead obliterates the night vision you had so carefully cultivated and protected throughout the night. The world that you had so easily navigated with nothing more than starlight and a dim red lamp, now closes in to a narrow tunnel of visibility directly in front, and the best you can do is follow the reflective dotted line down the center of the road.

Signposts advised me to watch for animals and so I proceeded with vigilance, expecting rabbits or maybe coyotes. I made it all the way back to the town and a few blocks from my hotel, when I noticed cows grazing beside the road. No, they were ON the road.

This was odd, since fencing parcels all the grazing land. Where the road interrupts the barbed wire, a cattleguard is used---bars of steel, spaced to make it hard for a cow to cross (its foot slips into the gaps), but allowing tires to roll across. Somehow, these cows had ended up on the wrong side of the fence. And they probably couldn't get back!

I looked to the other side of the road. Cows were milling around there too. I was surrounded, and suddenly I was about to plow into one! What?! Huh? I slammed on the brakes but it was too late.

Just before the collision I felt the world in slow motion. I thought I would suffer the fate of drivers from my part of the country that encounter large moose and elk; the animal is gutted as it crashes through the windshield and its butchered parts are delivered into the driver's lap. Sometimes the driver survives. My mind raced in my time-altered world, but my body couldn't react.

The car smacked into the cow, which skidded up the hood. Before reaching me, however, it stopped, slid back, and flipped onto its other side, flat on the road. Then the poor animal somehow got to its feet and staggered off.

I survived too. My speed was low enough, and the cow soft enough, so even the airbags stayed stowed. With the cows watching carefully (one with tenderized ribs), I drove at snail's pace the last few blocks home.

All this is a lesson in the dangers of field work in color science. It’s like the picture of Dorian Gray: I program the camera for high dynamic range to look at the stars, but my own vision still suffers due to a bright light in the near field. That field had a few bovine visitors, hardly at the limits of human perception. Go figure.