HDRI (High Dynamic Range Imaging) is a technique that I have been experimenting with for quite a while now, but with limited success. The technique involves taking 3-7 photographs of a subject with 2 stops of exposure difference between each photo. A little back ground: the human eye can see about 14 stops of light (stops being a unit of lightness/darkness) however, the eye can change its sensitivity as we look at a scene, this gives us the feel of 24 stops. The average digital camera can only record around 8-11 stops. This is why photographs sometimes can’t capture all the information that our eyes can see. An example is a moon lit night, your eye can see detail in shadows on the ground then you can look at the moon and see detail in the moon, a camera can only capture detail in one of those.
This is the best that a DSLR can do with one exposure.
With HDRI you can put together huge amounts of data and actually capture more detail than the human eye can see. The only problem with this is that there is nothing to do with this file. You can’t print it, no paper has 24 stops of dynamic range, you can’t email it, no monitor can display that. So, what you have to do is selectively pull out the detail in the highlights and shadows until you get a file that can be used. The way you do this is open to interpenetration and expression, and there are many programs that help you make those choices. For the most part, I use Photoshop and Lightroom to make these adjustments. With Lightroom 4 Adobe allowed you to work with 22 bit images inside the program (before that you had to go to Photoshop). This is great because you can get a very realistic look with it. I did some photography for a B&B out here and was able to get great detail in the room and still show off the beautiful view out the window. With Lightroom this looked very natural and “real”.
There is of course another way to process HDRI photos and it gives them a very gritty distinctive look. Even if you don’t know about HDRI you will recognize the look when you see it, its full of texture. I call the look hyper-realism and with out going too far into here is why it works. The eye sees texture as something light next to something dark. What I mean by that is a 3D object gives off a shadow and has a highlight. If there is no contrast on its surface we perceive that object as smooth. What HDRI lets you do is extract shadows and highlights from everything in the scene.
Below you can see how the mountain comes alive and punches out, but the foreground is also much more interesting because it has texture and more color. This was done with one of Photoshops presets, scot5 its called. The preset is named after Scott Kelby who started Photoshop TV (a great podcast for picking up random PS tips). The other preset worth playing with is RC5, also named for a Photoshop TV guy, its a mild version of Scott5.
HDRI representation of Denali, with that HDR "look".
I found that Denali National Park really looked great with the HDRI effect. I ended up shooting a bunch of scenics with it. I even did a HDRI panorama. You want to talk about working with big files, take 9 5D MKII pictures and squeeze them into one panorama, the 8 bit version was 500 MB. Here is the Polychrome mountains in HDRI and panorama.
And oh yes, they do have bears there. Smaller and more fuzzy than we have here. But still pretty cute.
Polychrome Mountains in HDRI and Panorama
Cute little fuzz ball