I’ve dabbled a bit with HDR (high dynamic range) imaging, and haven’t been too thrilled with the results. So I finally invested a little time a couple of days ago reading up on qtpfsgui, the free, open-source software that I’ve been using to play around. The discussion on the Flickr group for the software was particularly full of useful hints and tricks.
A little explanation: True HDR can’t actually be displayed on something as pedestrian as a computer monitor. So once you’ve constructed an HDR image from multiple exposures of the same scene, you still have the problem of figuring out how to display it in a visually appealing manner. That’s where tonemapping comes in: it’s the combination of art and science, the wizardry that uses manipulation of contrast, colors, and edges to fool your eyes into thinking they’re seeing a greater dynamic range than any monitor can actually display. This is the step that has been problematic for me, as I’m neither an artist nor a scientist. I can’t tell you the technical difference between the algorithms, and I don’t feel too confident in my own artistic judgment in adjusting the parameters to produce the final product.
Fortunately, I did what every good dilettante does: took refuge in someone else’s instructions. The process is relatively simple, but not one that had occurred to me: produce two differently-tonemapped versions of the same scene, and then overlay one upon the other using Photoshop or the like. Doing this allows you to produce a composite image that captures the strengths of different tonemapping operators. In particular, the recommendation was to use the Drago process to create the base layer; it produces an accurate, real-colored, but very dull and low-contrast image. Above that, an image produced using the Fattal process, which yields dramatically more contrast, and intense and saturated colors, can be overlaid, and the opacity of the overlay adjusted to produce the desired final effect. Simple, easy, and tremendously effective!
Of course, you shouldn’t take my word for it. Check out some side-by-side comparisons instead! I tried this first on my most recent HDR image, the night skyline view along the railroad track from Hyde Park Boulevard. Here’s the old version:
And the new, improved version:
Much better, no? Here are some more comparisons. Cityfront Plaza downtown:
The railroad and skyline from 18th Street:
The Michigan Avenue plaza:
And NBC tower:
Now that I have this down to a reasonably easy process, hopefully I’ll try some new shots soon. In particular, I want to try daytime photos.



















