Monday, October 29, 2012

High Dynamic Range

I'm wearing my photography hat today so all you runners and swimmers out there will have to bear with me.

Doug and I both really enjoy photography. He has, on average, more opportunity to play with his camera than I do but we both like to go out and try play with our cameras, lenses and flashes. A few weeks ago, when the fall colours were at their peak, we headed out to capture the Niagara sights and then came home and played with HDR.

For those who don't know, HDR stands for High Dynamic Range.

Photography lesson: cameras can only capture a certain range of light and it's nowhere near the range that our eyes can see. So, for example, if you are looking at a scene that has bright sky and trees with deep shade under them, the camera will not be able to capture what our eyes can see in the sky (clouds etc) and the shade (the flowers under the trees). The range between the dark and the light is too far for the camera.

High Dynamic Range tries to deal with this by letting you layer photos on top of each other.

Here is how it would work for the scene that I just mentioned. I would take three photos. In the first photo, I would expose for the sky so that I could capture all the lovely clouds. In the second photo, I would expose for the mid-range (the trees for example) and make sure they looked good. In the third photo, I would expose for the dark areas (the shade under the trees) and make sure I captured the detail in there.

Then I would layer the photos on top of each other and, voilà, I create a photo that has the range of light that we see with our eyes.

Watch below:

In this photo I exposed for the shady areas. Note how the sky is really blown out? 

In this photo I exposed for the mid-range (the trees etc).

In this photo I exposed for the sky so you can see the clouds but the vineyards are very dark. 

Then I tossed all three photos into my HDR program and, voilà! Everything exposed properly in the same photo. 

Sometimes HDR can be really over the top and the photos end up looking really fake and oversaturated. When it's done with a bit of control, it can work out quite well. Particularly with landscapes. 

And that, folks, is the kind of stuff I do when I'm not running, swimming, curling, cycling or cooking yummy dinners with Doug. 


  1. I don't buy, even for a second, that you have time when you're not running, swimming, curling, cycling or cooking yummy dinners with Doug. Or recovering (sleeping!) from one of the above mentioned items.


  2. Pretty pictures! Me gusta.

    This is one of the kinds of image processing that makes up my day job, by the way. I spent a lot of time about five years ago writing code to read HDR data formats, create HDR master images from multiple "low dynamic range" images, and generate "tone mapped" LDR image output from HDR images. There are so many ways to do that last step. (