Monday, September 7, 2009

The Egyptian Museum and HDR Imaging

We had a nice day of shooting at the Rosicrucian Egyptian Museum. We opted not to go inside, as there were lots of subjects to photograph on the grounds.

John had been wanting to experiment with HDR (High Dynamic Range) imaging using his point and shoot camera and the day was perfect for it. Overcast skies provided really even light.

We arrived about 9:00a.m. but weren't the first one's there. I got out my trusty point and shoot and my tripod (a necessity for shooting for HDR). I explained in an earlier entry what HDR is and basically how it works. What I don't think I pointed out was that  you want to keep the same aperture for each of the three shots and change your exposure by changing the shutter speed. The image above and to the right is the goddess, Sekhmet, the goddess of war, disease, plague and famine. Additionally she also represented healing and doctors, as in the eyes of the ancient Egyptians the gods needed to have a opposing ,and therefore balancing, attributes. This item is not an artifact or reproduction, but rather a modern artistic depiction of the goddess. (Thanks to Eric Bricmont at the Egyptian Museum for the information about Sekhmet).
Once you have your three differently exposed images, the computer sofware works its magic. It aligns the three images and selects the parts of each image it wants to create the final HDR image. Remember, we start with about 5 f/stops, then add 2 more, then add 2 more so now we have the equivalent of about 9 f/stops of range. We're getting closer to what you can see with your eye.
After the software aligns the images and creates the HDR image, you get to "tone map" it to restore the proper tonality. There is "normal" tone mapping, and there is a "grunge" preset (see lion above right). When you look at the "properly" exposed image, the sky was blown away. In the HDR image, there are many more tonal values present.
The image to the below and to the right is John's favorite of the day. It was taken from inside a room with two perpendicular walls and a bunch of columns insided. One one wall were openings (we can call them windows) that look out over a pond with lilly pads and a beautiful palm tree. This was the shot and it was begging for HDR. Otherwise, there would be no sky.

John made one image with normal tone mapping and this one, which was a bit on the "grunge" side. Just goes to show, grunge can be good!

The Rosicrucian Egyptian Museum is a great place to visit. Lots of ancient history. Next time we go, we'll take the time to tour the inside of the museum. And, they have a planetarium there as well.

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