Although its been popular for a while, I’ve recently begun working with multiple images to produce high dynamic range (HDR) photographs.  What is HDR?  HDR is a series of methods developed to produce a high dynamic range image from a set of photographs taken with a range of exposures.  There are multiple methods for producing an HDR image, from blending multiple shots in Photoshop to processing a single RAW image multiple times and blending those in Photoshop to using HDR software like Photomatix.

My goal here isn’t to tell you how to make an HDR photograph, because there are already fantastic tutorials out there, written by people much more talented than I am.  Probably the most complete tutorial was written by Royce Howland over at Naturescapes.net.

Because you can probably already produce an HDR image on your own, I want to share some nuances of the process I’ve learned to make your images look more realistic.  These aren’t new techniques, and I didn’t come up with all of them myself–to give credit where credit is due, Royce Howland, E.J. Peiker and Paul Stoczylas are the masters.  I’m but a student.

Part I: Getting rid of the halo

Photomatix is a powerful program and has a very user-friendly interface that pretty much does the work of producing an HDR image for you.  Because there are no monitors that can visualize that kind of dynamic range in an image, you must first tone map the image before being able to display it.  You have two options: Details Enhancer (DE) and Tone Compressor (TC).  DE is the default, and although it lacks some mid-tone contrast, it looks a lot better than a straight TC image which is way over-saturated.

The problem with tone mapping with only one algorithm is that you’re limited by each one’s constraints.  For instance, halos are a big constraint of the DE algorithm:

Towers of the Virgin, Zion National Park, Utah, June 2009

This shot looks pretty good, but you notice at the junction between the sky and the cliffs that the sky turns noticeably light blue–that’s because I only tone mapped with the DE algorithm.

This halo can be especially problematic in images where you have trees against the sky.  In this series of posts, I’ll cover a couple of methods I’ve learned to make the HDR image look a little more  realistic and squelch that halo!

Stay tuned…