Highs and Lows

High dynamic range (HDR) imaging is one of those techniques that divides photographers. To some purists it's just not “real” because it uses more than one frame. To others it looks unnatural due to exaggerated colours and contrast. Another group loves the drama and boldness of those very same exaggerated colours and contrast. Personally, I'm in yet another group that likes subtle HDR, the variation that should be hard, if not impossible, to pick as HDR. It allows images, as you would expect, a wider range of brightness while still appearing natural. The trick, I think, is to do this with a sensitivity to the subject matter and reality.

The human eye and brain combine to take in a far wider range of brightness than digital or film ever could. But our brains also know when we are looking at an image rather than reality. Our brains expect the bright sunlit highlights of a photograph to be brighter than, for example, a bright yellow leaf in shadow. So giving similar brightness and contrast treatment, or visual importance, to all areas of an image will look unnatural.

Here's three frames from the camera. The left one isn't of much use as it's too dark. The middle image has the highlights just under control but little shadow detail and shows the limitations of a single frame. The right hand image has overexposed highlights but some nice shadow detail, again showing the limitations of a single frame. Below are three ways of combining these three frames.

On the left is a “flat” HDR merge. This has promise and could be massaged to produce a pleasing final result. But note how the trees at top-centre have similar brightness and contrast range to the rock bank on the left.

The central image has been given the high contrast and over-the-top colour HDR treatment. Again the left rock bank and distant trees are similar in brightness and contrast. As is almost everything in the frame. Sure it's bold, but it's bold everywhere which leaves the viewers eye roaming wildly, never settling down. Trying to work this image into a visually pleasing three-dimensional scene would be impossible.

The right hand image is a manual combination of the three frames. Stacked as layers in photoshop, brightest on top, I've gradually erased parts of the top and second layers. Each small section of the image now has reasonable contrast but the different brightness of each section now allows a journey through the image. The forest on the left now has dark shadows and the distant trees now look... well... distant! Sure it's no masterpiece, but with a little burning and dodging as shown below it can be worked into a pleasing capture of what it really looked like, not just to my eye, but to my mind.