This past weekend I was lucky enough to be spending my Christmas holiday with my wife’s family in the North Country in New York. For those of you that don’t know, the North Country is that region of New York and Vermont from about the Lake George area to the Canadian border. I’m not originally from the North Country, so that might be a bit off, but certainly just saying Upstate New York would not have been sufficient. I say I’m lucky because I had the opportunity to be present for a rare event, and had my camera along to document it.

The event I speak of was that the Champlain Bridge (also known as the Crown Point Bridge) was finally going to be demolished after a spiral fracture had been found in one of its concrete support piers. That fracture led to the bridge’s closing on October 16, 2009. The closing of the Champlain Bridge had vast implications in the region; the nearest bridge into Vermont is 50 miles south of Crown Point in Whitehall, and the nearest bridge north of Crown Point is over 100 miles away at Rouses Point. In between, Lake Champlain is serviced by several ferries, but only one of them operates 24 hours a day, and none of them are open to industrial traffic.

With the bridge condemned, a vital link for many individuals and companies on either side of the lake was severed. People living on opposite sides from where they worked faced an extra 2-4 hours of travel to and from work, and trailers would be forced to detour many miles to get to the same location.

The Champlain Bridge, which was dedicated and opened on August 26, 1929, was demolished with explosives 80 years later on December 26, 2009.

The morning of the demolition was cold, snowy, and visibility was very poor. None but those with permission to access the Crown Point location, and perhaps some from Vermont were actually able to see the bridge implode. For most of the public waiting to see the bridge’s final moments, all that was seen was fog punctuated by the series of bursts indicating that the charges had gone off.

The afternoon before and morning of the demolition, I set out and took several pictures at the scene, but, lacking a media pass, did not get a photograph of the actual implosion. Meanwhile, you can see the somber and eerie photographs of the Champlain Bridge in its waining days on my Flickr account in my Champlain Bridge Demolition set.

The replacement bridge is expected to be in place and opened in the summer of 2011¹.

All pictures in the aforementioned set (with the exception of the “Protection” meta-photo) were taken with the following lens, which I highly recommend:

1. NYSDOT’s current schedule for the Lake Champlain Bridge Project [↩]

There was a time when one bit per pixel was enough. Back in that time, there was only one color channel with only one value for each pixel; either on or off. One bit per pixel was sufficient. Next came progressively more graduated gray-scale, up to the 256 levels provided by a one-byte, eight-bit value. This was about the period that I got my first computer, an Apple IIc in all of it’s green-display glory.

Then color came along: red, green, and blue. Now those 8 bits were rationed out; three to green and red and two to blue in the common case¹. Then came 16-bit color, followed by 24-bit color. Now red, green, and blue were on equal footing, each holding 8 bits of information. Soon after came the cake-is-a-lie 32-bit color, which is rarely adds anything more than 24-bit color².

This brings us to today, where most computer monitors advertise the 16.7 million colors afforded by 24-bits of color data. For most of us, this is plenty, as the human eye is estimated to only be able to distinguish 10 million colors. Thus, 8-bits per channel is generally sufficient for displays and is why there haven’t been any big pushes to extend that range³. The issue is no longer one of how many colors but of how broad a gamut of colors.

The standard gamut used in most displays is called sRGB. sRGB is a rather limited gamut but one that has such wide acceptance that, in the absence of any information to the contrary, it is the assumed default for images. It’s a form of least-common-denominator for electronic displays. For most uses that involve a computer display as the means of consumption, using sRGB is sufficient. However, sRGB lacks the ability to represent saturated yellows, greens, and cyans. This shortcoming is readily apparent when it comes to printing images. The printer has a different gamut for CMYK. Some colors that are in sRGB aren’t in CMYK and visa versa. The more saturated blues and yellows that CMYK can print but aren’t represented in sRGB can leave images of the sky and flowers a little under-saturated.

In order to handle the wider range of colors, alternative color spaces must be used with wider gamuts. Examples include Adobe RGB (1998), PhotoPro RGB⁴, and Adobe Wide Gamut RGB. These gamuts allow even more colors to be represented.

Or do they… In an analog system, sure; just as the cardinality of the set of real numbers, , is greater than the cardinality of the set of rational numbers, , so too, the number colors in Adobe Wide Gamut RGB is greater than the number of colors in sRGB in addition to containing all of sRGB even though all those sets have an uncountable number of members.

However, in the digital format, each component is chunked into quanta. For 8-bits, there are 256 distinct values. When you expand the gamut, the number of representable colors remains exactly the same (256), but the distance between quanta of color is larger. Think of it as taking a 24-inch ruler and stretching it. The ruler covers more distance, but there are still only 24 sections on it. There is just more distance between each hash.

When this extended gamut is invariably cast back into a smaller gamut, such as sRGB, the lack of color data resolution causes a phenomenon called posterization. If you’ve ever used 8-bit mode during a remote session on your 24-bit desktop, you’ve seen this effect. The combined effect is somewhat similar to a rounding error.

One way to combat this posterization is to increase the resolution of the color data, e.g. from 8 to 16 bits per channel. With 256 times as many hash marks on the color ruler, the color gamut can easily be expanded to twice its size without causing the banding effect.

As most digital cameras still capture in sRGB and output to 8-bit JPEG, the common photographer has nothing to worry about, but for the more advanced photographer who wishes to have more control over their output, a larger gamut, such as Adobe RGB, and greater resolution are more important. My camera, the Canon Rebel T1i (pictured below) offers an output to RAW format⁵. Each pixel of the sensor has 14-bits of resolution, so it makes little sense to use a working format with less bits per channel. Thus, after importing the RAW file, my working format is Adobe RGB with a 16-bit TIFF. The TIFF format is an uncompressed beast, but it ensures that I don’t lose any of that color data in translation.

Getting the results that you want can be cannily uncomplicated. Most photographers aren’t even worrying about all this as nearly all decision making, aside from composition, is made inside the camera. But when more control is desired, the entire workflow needs to be insulated from introducing error into the process so that the end result is precisely what the photographer intended. And it’s at this time when eight bits really isn’t enough.

1. The reason being that green is primary color to which human eyes are most sensitive, and small changes in green are more easily noted than in red or blue. This fact is further utilized by many steganographic programs which embed information in image files. [↩]
2. There are some 32-bit color implementations that use 30 bits (10 bits per color), but most commonly, the extra 8 bits are used for non-color data or padding. In fact, Windows 7 will support up to 48-bit color, but no graphics cards yet support it; only a few graphics cards currently support 10-bit-per-channel color; and, fewer still monitors can display the 1 billion+ colors available with 30-bit color. [↩]
3. Though, as mentioned in the previous footnote, Windows 7 is breaching that ceiling. Read more about the advance of digital color resolution on Wikipedia [↩]
4. Which uses an ‘imaginary’ blue as one of its primary colors. [↩]
5. A proprietary version of the TIFF format; each manufacturer often has their own proprietary extensions. [↩]

I’ve finally uploaded a first batch of pictures from the StackOverflow DevDays in Boston. Out of over 350 pictures taken, only 20 made it to this cut, with several not-quite-as-good pictures that I may look at adding later. If you see any you’d like, let me know, and I’ll get a proper copy to you.

Taking photos at the event was very difficult. For human eyes, everything was fine, but for a camera’s lens, there was very little light. I didn’t use flash during the event; a common courtesy to both presenters and audience in an already low-light environment. It made me really wish that I had a 50mm f/1.4 lens like this one, though; too bad such wide aperture lenses are so expensive!

The other environmental difficulty for photography was all of the different light source types. There were fluorescent lights in the main area (blueish), recessed incandescent bulbs (redish-orange), and the projector light (near 6500K, or like-sunlight). So, in the picture at right, for example, the main subject, Joel Spolsky, was standing under incandescent lights. This gives him a redish-tinge. When correcting Joel’s white shirt back to white, the slides in the background, having a neutral tint before correction, end up tending toward blue after.

Regardless, I’m happy with the photos I did get. Again, feel free to check them out. Here’s the link in case you didn’t catch it earlier!

My StackOverflow DevDays Flickr Set