High Dynamic Range image of
stained glass in cathedral in Lisboa
After the ICANN board meeting yesterday, some of us went sightseeing. We visited a beautiful cathedral. It was amazingly fun and full of wonderful photo opportunities after spending a week trying find interesting shots in conference rooms and my hotel room.
One thing I realized after taking some shots of the stained glass was that the cathedral was a perfect opportunity for High Dynamics Range (HDR) imaging. The Wikipedia article describes HDR thus:
In computer graphics and photography, high dynamic range imaging (HDRI) is a set of techniques that allow a far greater dynamic range of exposures (i.e. a large difference between light and dark areas) than normal digital imaging techniques. The intention of HDRI is to accurately represent the wide range of intensity levels found in real scenes ranging from direct sunlight to the deepest shadows.
HDRI was originally developed for use with purely computer-generated images. Later, methods were developed to produce a HDR image from a set of photos taken with a range of exposures. With the rising popularity of digital cameras and easy to use desktop software, the term "HDR" is now popularly used to refer to the process of tone mapping together bracketed exposures of normal digital images, giving the end result a high, often exaggerated dynamic range; however, in this case neither the input nor the output qualify as "true" HDRI.
Because I didn't have a tripod, I couldn't shoot bracketed images, but I was able to take the RAW files that I was shooting and use Photomatix
to render HDR images of some of the stained glass shots.
Here is an example of the same image. The first one has gone through HDR and the second one has only had the levels adjusted. (Sorry, I rotated and cropped the second one so they don't look identical.) You can clearly see that in the second image, you lose detail in both the shadows and the highlights, whereas the first one is able to preserve both. You can argue that the HDR image is "doctored" but some argue that HDR is similar to the way our eyes work. Our eyes, apparently, are able to adjust VERY quickly to the brightness and change "aperture" as it scans between highlights and shadows providing with us with high dynamic range imaging in real life.
I think an argument can be made that HDR is "cheating", but I think it's a fascinating technique that I'm going to try learning more about. Hat tip to Justin who first turned me on to this and to Pat who helped me find the software. Also, I've heard that you can use Photoshop to do HDR, but that Photomatix is easier to use. Pat has a very cool landscape HDR shot and Justin has been experimenting with hand-held HDR.