Dynamic Range Enhancement

I had to come up with my own name for this, because there are so many buzzwords out there to describe this function, which is so commonplace in digital photography, and yet apparently so misunderstood. I was reading a thread the other day, and couldn’t believe how misunderstood it is. So hopefully, I can shed some light on the subject.


Nikon calls this Active D-Lighting while Canon calls it iContrast. It’s essentially the same as Adobe Photoshop’s Shadows/Highlights filter, a powerful post-processing tool that’s regularly used in professional post-processing to address an age-old problem; the limited dynamic range inherent in photography.

Dynamic range is the difference in spread between the lightest and darkest values that can be recorded on film or by a digital camera. For those of you who may be audiophiles, it’s the photographic equivalent of the loudest and quietest sound that can be recorded on a given medium. The bottom line is that neither film nor digital has anywhere near the dynamic range of the human eye, so the same problem occurs over and over; not all the values you wish to record can fit on the medium at the same time. Some compromise has to be made, so the exposure system attempts to capture as many values as possible, favoring the midtones. In a high contrast scene, the shadows and highlights suffer.

Through careful exposure, it’s possible to get the highlights at the expense of the shadows, or the shadows at the expense of the highlights. But the average image suffers from blown highlights and plugged shadows; these areas are nearly solid white and black, with virtually no detail whatsoever.

What Active D-Lighting and iContrast seek to do is to recover the lost highlight detail and fill the shadows with light to reveal dark details. Hence the terms, recovery and fill light, which you will see used in applications such as Adobe Camera Raw, and Apple Aperture 3.

But does it work?
When people use it, their immediate reaction is that it’s simply lightening the image overall. They usually don’t see the effect on the highlights at first. And for that reason, they assume that they can achieve the same results using levels or curves in Photoshop. While these tools can be effective for certain images, ADL and iC (and their Photoshop Equivalent) apply a High Pass-like algorithm to create separation between individual tones within the shadow and highlight regions based on the actual pixel values. Hence the term “dynamic”. The results can be quite impressive. What normally looks like an under- or over-exposed image comes to life. However this magic comes at a price.

Some images look perfectly natural, while on others the effect stands out like a sore thumb. If you look closely at these images you’ll begin to see the “halos” created by the algorithm. It’s not unlike becoming attuned to that metallic, whooshing sound present in overly-compressed MP3 files. The effect is similar to that in HDR (High Dynamic Range) images, which many people find unappealing.

Many post-processing applications have some sort of Dynamic Range Enhancement. Adobe Camera Raw calls it Recover and Fill Light. Aperture calls it Recovery, Shadows and Highlights. Capture One calls it High Dynamic Range. So this is really nothing new. But the fact that it’s built in to your camera allows you to compensate directly for scenes with challenging lighting conditions.

Should you use it?
Absolutely. Initially I used it full time on the “auto” setting. However, I have since found that it’s best employed with high contrast scenes that have an enormous spread in values, such as capturing fine detail within the mouth of a cave in bright sunlight. On an overcast day with cloud cover producing soft, diffused light, I keep it off. So like anything else, when you know how to use it properly, it can be a great advantage.

If your camera has the ability to bracket this effect, I highly recommend using this feature. You can capture two images at the same time, one with the effect and one without, and you can combine the best of each in post.

You can also use it to gain a one to two stop advantage in exposure. For example, if the exposure requires you to use a shutter speed that might introduce motion blur, set it one to two stops higher (using exposure compensation) and turn ADL or iC on, setting it at maximum if possible. Your images will be brighter and sharper.

In many cameras, you can simply apply the effect directly in post. If you shoot in RAW, you can take advantage of the increase in dynamic range when post-processing in Adobe Camera Raw, Aperture, Capture One and others.