JPEG Dynamic Range

Active D-Lighting


Nikon has included its Active D-Lighting feature on its DSLRs for many years now but it remains one of the best features for matching the tonal range incorporated into the JPEGs to the dynamic range of the scene being photographed.

For those unfamiliar with the feature, it has two elements: an exposure reduction designed to ensure capture of additional highlight information and a system for pulling additional shadow information into the JPEG. This second aspect is adaptive and attempts to brighten shadows in a context-sensitive manner, so that local contrast is preserved and the image looks well balanced.

As on previous Nikons, the D750 uses increasing amounts of exposure reduction and shadow lifting up to a total of 1EV for its extra-high setting. Sadly, despite the camera's impressive Raw dynamic range (as demonstrated on the previous page), the D750 doesn't offer the D4s' Extra High 2 setting that would make greater use of this capability.

The shadow-boosting aspect (D-Lighting) can be applied to Raw files, after they've been shot, but the full effect of Active D-Lighting is only achieved if original shot has been exposed appropriately, either by the camera or the photographer.

Flat Picture Control


The D750 also includes the 'Flat' Picture Control, first introduced on the D810. This is primarily designed for video users who, since they don't have the option to shoot Raw footage, can give themselves more post-production latitude by cramming extra dynamic range into their clips, so that it can be graded later (either to optimize the final brightness or to match footage shot with other devices). As you can see, the Flat PC option drops the contrast significantly, incorporating a broader dynamic range, albeit in a way that will usually produce a very 'flat' looking video clip or image.

However, an unintended consequence of producing an image with very low contrast but extra dynamic range is that it gives a much more usable preview and JPEG if you're shooting the kinds of extreme dynamic range Raw images illustrated on the previous page. Better still, it can be combined with the shadow lifting Active D-Lighting feature to incorporate an even broader range of tonal information.

In the plot above you can see how the 'Flat PC + ADL Extra High' option appears to incorporate around 12EV of dynamic range into a JPEG (From +4.3EV down to roughly -7.7EV). This means that it's able to produce a usable JPEG and certainly a very usable preview if you're trying to shoot to capture very high DR scenes, without most of the camera's monitor simply showing black.

Just to confirm there was no more to be gained, we exposed another image to just-about capture the brightest tone of our test chart: a process known as 'Exposing to the right.' Close examination of this image showed that the darkest few tones are essentially indistinguishable, so it's not really able to improve on the ~12EV dynamic range we've already shown.