A fortnight ago I blogged about HDR – An Art Form and Valid Imaging Technique. I had written “In a future blog post we’ll look at one or two tutorials and the two primary methods of HDR Processing” —and here’s that post.
HDR images are created using one of two methods, broadly speaking. One is to combine three (or more) bracketed exposures to create a single composite which is then ‘worked on’ and the other is to digitally post-process a single RAW using special software to increase the dynamic range.
Trey Ratcliff concentrates on the former method. The way that the human eye and brain visualize a scene is by “creat[ing] a ‘patchwork-quilt’ of the scene” and that is a pretty good definition as to how Ratcliff constructs his HDR images. Joseph Eckert explains how to use the latter method in his HDR tutorial.
Ratcliff presents a step-by-step how-to; he uses three bracketed exposures to create a composite final image using Photomatix, the most popular of such softwares. Stressing that each photograph is different, he steps the reader through Photomatix’s process (and also provides a video).
The first phase is preprocessing in which multiple source images are composited. In this phase one of the steps is optional removal of ghosting artefacts and chromatic aberrations. The next phase is the ‘real’ HDR phase in which Photomatix will confront you with an array of sliders. Ratcliff recommends which sliders to leave well alone, which ones to ignore, and which ones to tinker with, explaining exactly what they do.
Eckert uses Oloneo’s Photoengine and Nik’s HDR Efex Pro 2, and is very impressed with the former’s capabilities for its ability to get the whole job done by itself using a single source image. His write-up is less detailed in the nuts-and-bolts but more ‘big picture’ in overall philosophy.
Eckert offers his own set of tips, such as exposing for the highlights in your source image, using bracketed exposures in very high contrast situations, and – as does Ratcliff – recommending that each photograph be treated individually.
In his tutorial he provides his own base set of Oloneo Photoengine settings which are then adjusted on a per-photograph basis. Notwithstanding his admiration for Oloneo, he explains how and why he uses Nik’s Sharpener in a later step.
Both Ratcliff and Eckert are agreed on the point that HDR’ing an image will result in at least some noise and, so, they recommend using a de-noising software as the final step. Similarly, both also advise the newbie to try to keep their HDR images on the right side of reality and avoid getting, shall we say, ‘psychedelic’.
Done with common sense and restraint, HDR results in photographs that are simultaneously true-to-life and also artistic and slightly ‘painterly’. These two tutorials are a valuable guide as to how to achieve this effect.Tags: HDR, high dynamic range, Photography