Dynamic Range

The tone curves that smartphones apply to their JPEG output are often quite contrasty and the Nokia Lumia 1020 is no exception. In practice images have a "punchy" look, but often lack highlight and shadow detail. This limitation becomes obvious when taking pictures on overcast days. As you can see in the samples below the 1020 struggles with the brightness of the overcast skies which results in large clipped image areas.

We applied negative digital exposure compensation and highlight recovery in order to pull back some detail in the clipped sky.

In Raw conversion some highlight detail can be recovered, though. The first image below was developed with Adobe ACR's default settings. ACR's default tone curve is quite a bit less contrasty than the camera's, so all clipped highlights in the sky are gone, even without applying any highlight recovery or negative digital exposure compensation.

The light situation in the second sample was similar, but the clipping was even a touch more extreme. Nonetheless, most clipped areas could be recovered using the Highlights slider in ACR (-20). Some recovered areas have turned gray, though, indicating that at least one color channel had totally clipped.  We also slightly lifted the shadows (+16) for a more balanced tonal range in the image.

In the third sample it becomes obvious that highlight recovery is only possible within relatively tight limits. Despite applying highlight recovery and some negative digital exposure compensation, very little detail in the sky can be recovered, and large image areas have turned monochrome.

Out-of-camera JPEG, ISO 100
Adobe ACR, default settings
Out-of-camera JPEG, ISO 100
Adobe ACR, Highlights -20, Shadows +16
Out-of-camera JPEG, ISO 100
Adobe ACR, Exposure -10, Highlights -35

The ability to recover clipped highlights is one of the most useful aspects of Raw conversion. However, sometimes lifting the shadows can help create a more balanced exposure in high-contrast situations, too. When taken to extremes, it's even possible to create an HDR-like image from just one single Raw file. The problem is that shadow noise becomes more visible. We've played with the sample below to see how the Lumia 1020 fares in this respect. 

The picture was taken in a contre-jour situation that resulted in the monument almost appearing as a silhouette with very little shadow detail. In ACR we pushed the shadows (+70) which resulted in increased shadow detail, but most of the gain in detail is overshadowed by a huge amount of both luminance and chroma noise. Some banding is also noticeable. The shadow noise remains very intrusive, even when the image is downsampled to 5MP. We created a second downsampled version where we applied some noise reduction (luminance 40, color 50) before downsampling but the noise still can't be overlooked.

Of course noise will be less intrusive if shadows are pushed to a lesser degree, but overall it's safe to say that you should be careful when trying to increase shadow detail on the 1020's Raw files. There's a lot of noise hidden in those shadow areas, and if you pull the slider too far it will be visible even in small viewing and print sizes.

Out-of-camera JPEG, ISO 100, 5MP
100% crop
Adobe ACR, Shadows +70, no NR, 38MP
100% crop
Adobe ACR, Shadows +70, no NR, 5MP
100% crop
Adobe ACR, Shadows +70, no NR, Luminance NR 40, Color NR 50, 5MP
100% crop

White Balance

Modern auto white balance systems are usually doing a decent job in natural light but you can be slightly thrown off by certain artificial light sources and mixed light. Measuring the white balance before you shoot using a gray card is one way of getting things right, but many photographers, including myself, find it easier to snap away in auto white balance mode and correct later during Raw processing, if necessary. 

Out-of-camera JPEG, ISO 400
Adobe ACR, Temperature 3650 

The sample above was taken in a difficult light situation. The mix of the cool evening light outside and the warmer illumination of the museum's interior slightly confused the Nokia 1020's auto white balance and resulted in a very warm color cast on the building's interior elements. In a mixed light situation like this it's impossible to get the color balance right in all image areas, but here we wanted to focus on the interior elements of the building as they occupy the the image's foreground.

The image was captured with auto white balance at 4050K which we reduced in Adobe ACR to 3560K to create a cooler, more natural color response on the floor and columns of the building, and in the ancient basin in the foreground. 

Conclusion

Given the Nokia Lumia 1020 is only the second smartphone to offer Raw capture, we were not quite sure what to expect. After a lot of time playing with the phone's DNG files, it's safe to say that shooting Raw on the Lumia 1020 offers you some flexibility in post-processing, but not the same degree of flexibility you are you used to from your DSLR, mirrorless system camera, or even premium compacts, such as Sony's RX100.

Processing the 1020's DNGs is most useful for making white balance, tonal and minor exposure corrections. In terms of noise and dynamic range, the Nokia's files are better than we would have expected from a smartphone, but nowhere near DSLR territory. The ability to recover clipped highlights is limited, and lifting shadows will inevitably result in a lot of noise in the affected image areas, unless you keep the modifications to a minimum.

There is also not much point in worrying about detail, sharpness, and to a degree, noise if you are not intending to use the images at full resolution. At the image sizes that are used for social sharing and online posting, typically no modifications of any of those parameters will be visible. Nevertheless the ability to optimize images for print and large viewing will make the Lumia 1020 even more attractive to serious users. It's great to see Nokia yet again lead the pack in the area of smartphone imaging, and we hope other manufacturers will follow in the near future.

Raw files for download

Below are a few Raw images that you can download and tweak to your heart's content: