Thursday, October 15, 2009

Returning to HDRi

The very lightest and darkest parts of an image can often be difficult for a digital camera to capture. Especially if the scene has strong contrast in the lighting, or perhaps looking directly at the sun. The technical reason is that most digital cameras only have a limited dynamic range (the way in which it captures the lightest value to the darkest). When the scene has a wider range of lighting the camera light meter is forced to select the range that it will best try to expose. If it choose to expose for the shadow (as you have pointed the camera there) the lightest parts get over exposed. Point at the darkest areas will leave the shadows dark and without detail.


- 1.0 EV This series was taken using Bracketing with 0.5 steps in EV + 1.0 EV
- 0.5 EV 0.0 EV (normal exposure) + 0.5 EV

The first way to overcome the dynamic range limitation of your camera is to take a series or bracketted exposure setting (ie with different EV values) Like the set above and hope that at least one of them will turn out Ok! Trouble is the image with the best sky has the land mass in detail-less shadow and the one showing detail of the beach has the sky bleached out.

Using Dynamic Photo with photographic tone mapping

The technique know as HDRi (which I have mentioned before) lets you combine each of these separate exposures and make up a new image that contains the detail from the extended tonal range. In this case I have used Dynamic Photo and tone mapping to match the range of the human eye. And now I have a photo that looks like the scene I was trying to take.

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