HDR, or High Dynamic Range, imagery was all the rave several years back, and as a result became one of the most over used and abused techniques in the industry. But that doesn't mean we should abandon it altogether.

Good HDR images allow for the correct exposure of highlights and shadows in an image that has extremes at both ends of the scale without losing the rich details at either end. Bad HDR images look like something straight out of a Sci-Fi movie.

The trick is to balance when and how this technique is applied.

What types of images benefit from HDR?

Knowing when – and more importantly when not – to use HDR is the first critical decision to make. If a scene is evenly illuminated, it is not a candidate for HDR. If a scene has extremes in either the highlights, or the shadows, or both – it is a good candidate.

Example include landscapes on bright, sunny days; shooting indoor settings that include sunlight from a door or window; or capturing skyline lights at sunset.

What methods are available?

There are two main methods for creating HDR images. The first is done by shooting a number of images ranging from under exposed to over exposed and then combining them into one.

Using Multiple shots

The easiest method is to produce the final image in camera – or in smartphone – and is supported in most models today. Menu settings will let you control the number of shots to take and the +/- exposure compensation to use for the outer limits. The images are then combined into one final picture in camera.

Another good method is to use Adobe Lightroom to do the work for you. Simply choose the images to work with and select Edit-Photo Merge-HDR from the menu. A dialogue box will allow the software to Auto Align the images, and control he amount of Deghosting which handles object moving across the shots to be merged.

The key to producing an HDR image that is not “other-wordly” is to ensure you shoot images with the correct exposure bracketing and take the right number of shots.

Exposure bracketing

Exposure bracketing is the amount of over-exposure you will need to capture all the details in the shadows and the amount of under-exposure needed to produce highlights that maintain their details while not blowing out.

The best way to do this is to use test shots. Shoot at +/- half stop increments and look at the image produced to ensure that all the details are captures that you are looking for. Check the histogram to ensure that while you have pushed the boundaries to the left/right, you haven’t pegged either side (were you would be loosing pixels). This will give you the upper and lower limits.

Next choose the number of shots to take between the two exposure extremes. Three is the minimum number – one over-exposed, one at correct exposure and a final under-exposed. However, this will produce so-so results if you have a scene with lots of highlights and lots of shadow details (which is why you choose to shoot HDR in the first place). A typical scene will need five exposures (very under, under, correct, over, and very over exposed) – but I have seen situations where seven exposures are required to get the best range.

Using a Single shot

The second method is to produce the HDR effect from a single image using an Adobe Photoshop Plug-In. I am partial to the NIK Collection, but there are a number of good applications on the market. The key is to start with an image that is neither over nor under exposed to give the software the most flexibility in applying the effect. Then apply the filter effect judiciously so as to not create a Franken-picture. Trial and error will usually get you the result you are looking for.

HDR is not hard to do, and with a little practice, it can be one of those tools that - while used infrequently – can make for some dramatic imagery.

Photo credits: Karen Foley.