Lab Report - JPEG Tone Curves /Dynamic Range

By Rishi Sanyal

Our Dynamic Range measurement system involves shooting a calibrated Stouffer Step Wedge (13 stops total range) which is backlit using a daylight balanced lamp (98 CRI). A single shot of this produces a gray scale wedge from the camera's clipped white point down to black (example below). Each step of the scale is equivalent to 1/3 EV (a third of a stop), we select one step as 'middle gray' (defined as 50% luminance) and measure outwards to define the dynamic range. Hence there are 'two sides' to our results, the amount of shadow range (below middle gray) and the amount of highlight range (above middle gray).

To most people highlight range is the first thing they think about when talking about dynamic range, that is the amount of highlight detail above middle gray the camera can capture before it clips to white. Shadow range is more complicated; in our test the line on the graph stops as soon as the luminance value drops below our defined 'black point' (about 2% luminance) or the signal-to-noise ratio drops below a predefined value (where shadow detail would be swamped by noise), whichever comes first.

Note: this page features our interactive dynamic range comparison widget. The wedges below the graph are created by our measurement system from the values read from the step wedge, the red lines indicate approximate shadow and highlight range (the dotted line indicating middle gray).

Cameras Compared

The graph below compares the Nikon 1 V3's JPEG tone curve to its older predecessor, the V1, as well as some of its most obvious competitors.

With all dynamic range settings off, the V3 provides a total JPEG dynamic range fairly similar to what we've come to expect from cameras in its class (Sony RX100 III, Panasonic GM1), though it falls short of the smoother highlight roll off and brighter shadows the Sony Alpha a6000 offers. Compared to its predecessor, the V1, the V3 has slightly higher midtone contrast, evidenced by the steeper rise in brighter tones and the somwhat darker deep tones. This comes at the cost of some shadow range. Also of note is the smoother roll off in highlights compared to the V1; this ensures that brighter tones are rendered with a smoother transition to clipping.

ISO Extension Settings (lack thereof)

The Nikon 1 V3 does not offer any low ISO extension modes, so the lowest ISO one can use is its base ISO of 160. We can't say we mind the lack of such extension modes, as they potentially come at the cost of significant highlight range. Furthermore, one can 'simulate' these lower ISOs by simply overexposing at base ISO, and then pulling back the exposure accordingly in post-processing (or, better still, using an ND filter).

Active D-Lighting: Real World

Nikon's Active D-Lighting (ADL) modes attempt to retain highlight detail in high contrast scenes. It does so by decreasing actual exposure (to keep highlights from blowing), and then using a lower-contrast tone curve to pull in more tones from shadow and highlight areas. As a dynamic range-enhancing mode, Nikon's implementation is particularly clever: although the camera decreases exposure to retain highlight detail, overall image brightness and contrast are well maintained.

This is in contrast to other dynamic range enhancing modes we've seen that decrease image contrast (notably: Sony's DRO modes). Nikon's ADL modes, on the other hand, show only the slight decrease in global contrast necessitated by the recovery of additional highlight tones. This can be seen in our real-world example below, where the V3 takes on a very challenging high contrast scene:

Off
Low
Normal
High
Extra High
Auto
Raw (ADL Normal Exposure)

Progressively higher ADL modes bring back highlight detail (look at outdoor scene details through the windows that emerge using higher ADL modes), while generally maintaining the brightness and contrast of shadows and midtones. Often it's possible to recover even more highlight detail if you shoot Raw - outdoor scene detail clearly blown in the 'ADL Normal' JPEG are recovered by ACR from the extra information available in the red and blue channels in the Raw file (which you can download here).

Note that although we boosted shadows in the Raw file to reveal more detail, generally you may find yourself limited as to how much shadow boosting you can get away with. This is because of the rather high noise floor of the V3 sensor - especially visible when boosting shadows at low ISOs. In our low light studio scene, a +4 EV push of shadows reveals significantly more noise with the V3 compared to the Sony RX100 III, which you can see in the crops below. In this comparison, both cameras received the same amount of total light (focal plane exposures were matched at 2.5s | f/5.6), so it's clear that the RX100 III is a better performer, due to its lower noise floor.

Nikon 1 V3 (+4 EV)
RX100 III (+4 EV)

A Note on Nikon's ADL Implementation in the V3

Sadly, the implementation of ADL in the V3 is rather odd. The low/normal/high/extra high modes shown above are only offered when using the camera in 'Full Auto' (the green camera icon) mode. Additionally, they're not actually enumerated 'Low', 'Normal', etc.; instead, an unmarked slider allows you to adjust the degree of ADL.

In PASM modes, only 'On' and 'Off' options are offered for ADL, with 'On' actually being 'Auto'. ADL Auto means the camera decides just how much exposure compensation to apply to retain highlight detail. Which ultimately means that in PASM shooting modes, you cannot choose the level of ADL. This limits the creative potential these modes offer in comparison to what is available in Nikon's other offerings (and, notably, the cheaper D5300).

Furthermore, we find it a bit odd that more control over ADL is offered in the 'Full Auto' mode, whereas less is offered in the more creative PASM modes. Shouldn't it be the other way around?

Active D-Lighting: Studio

We could not test all ADL levels in our studio test because the V3 only offers 'ADL Auto' in the more manual operating modes required for our studio tests (explained above). With our wedge target, 'ADL Auto' chose a setting of 'Low'. Below, you can see the effect of the Nikon 1 V3's ADL Low setting on the JPEG tone curve. Since exposure is not adjusted in this mode, no extra highlight information is gained, and the end result is simply that shadow tones are slightly 'opened up'.