Shooting Raw with the Nokia Lumia 1020
1 Image Detail & Noise
Smartphone cameras have improved a great deal over the last couple of years, and those improvements have had a dramatic impact on the market for consumer-level compact cameras. Sales have plummeted as most consumers simply don't see the point of carrying and paying for a compact camera when their smartphone delivers image quality that is beyond what's needed for social sharing and on-screen viewing.
The situation is slightly different in the enthusiast compact space, though. Compact cameras targeted at enthusiast users come with one feature that until recently no smartphone could offer: Raw file capture. The ability to process Raw files and modify shooting parameters after capture on your computer's high-resolution monitor is something many serious photographers don't want to live without.
However, as usual, smartphone manufacturers are moving fast, and in November 2013 Nokia launched the first smartphone with Raw capture: the Lumia 1520. The same feature was made available through a firmware update on Nokia's flagship smartphone, the Lumia 1020. Google also announced the implementation of Raw file capturing capabilities in future versions of Android. So it seems Raw capture is about to become a common feature on smartphones, at least on high-end models.
What does that mean for mobile photographers though? We already had a look at the Nokia 1520's Raw files in our full full review of Nokia's latest model and found the advantages of shooting Raw on the 1520 to be limited. Of course you have the flexibility to modify image parameters such as white balance, sharpness or contrast in post-processing, but it's difficult to squeeze additional detail out of the Raw files and the 1/2.5-inch sensor's limited dynamic range means only very minor shadow and highlight corrections can be applied.
Therefore, we were quite curious to find out how the Lumia 1020's Raw files would fare in processing. In our review we were quite impressed with the phone's JPG output and with its larger 1/1.5-inch imaging sensor. We expect the 1020's sensor to offer more dynamic range than the small-sensor 1520. We installed the Nokia "Black" update on our Lumia 1020 and then went out to take pictures in a variety of light situations. Back in the office we processed them in Adobe ACR to see if they allow for any improvement over the out-of-camera JPEGs.
The JPEG-engines of digital cameras apply detail-smearing noise reduction to the image-data that is captured by the sensor, even at low ISOs. If you need maximum detail in an image and are happy to accept some noise, converting a Raw-file with noise reduction set to zero is therefore a good option. Most Raw-converters will apply some noise reduction, even with the slider in the zero position, but it's still the closest you can get to a noise-reduction-free image.
To find out how much, if any, additional detail you can squeeze out of the Nokia's Raw files we processed a couple of low-ISO files with different noise reduction and sharpening settings in Adobe ACR.
For the first sample we set luminance noise reduction to zero and applied some fine sharpening (Amount 56, Radius 0.8, Detail 41). In the 100% crop of the brickwork below you can see that higher levels of detail can be achieved but the difference will only be visible at a 100% magnification. Apart from the obvious tone curve differences, edge sharpness is better in the converted Raw file and some additional low-contrast detail in the brickwork of the church has been revealed. On the downside you also get noticeably more grain in areas of plain color, such as the sky or the green roof of the building, and the shadows.
In a second step we downscaled the converted Raw image to 5MP in order to compare it to the 5MP JPEG that is captured alongside the DNG file. At the reduced image size the Raw file's grain is almost entirely averaged out but the increase in detail is gone, too. Thanks to Nokia's pretty efficient downscaling algorithm it's almost impossible to see a difference between the 5MP out-of-camera JPEG and our processed image.
Overall, in terms of detail, processing your images is only worth the effort if you are planning on using them at native resolution (the images below were captured separately because the camera can only save a 38MP RAW or a 38MP JPEG along with the usual 5MP JPEG.)
High ISO Noise Reduction
Noise reduction does its job by blurring noise. Some noise reduction algorithms are more intelligent than others but, no matter what camera you are shooting with, noise reduction inevitably also blurs some fine detail. Even with noise reduction "switched off" some of it is applied to your images. Enthusiast compact cameras and digital SLRs at least give you some control over this parameter.
This is not the case for smartphones. You are stuck with the amount of noise reduction that is deemed right by the engineers. On the Nokia Lumia 1020 you can apply your own noise reduction mix by converting the device's DNG files. In this section we are having a closer look at the Nokia's high-ISO Raw files.
When shooting in auto mode the 1020 never really goes higher than ISO 800 and relies on its image stabilization system to get a sharp image. The night scene below was even captured at ISO 640. At this sensitivity some loss of fine detail and grain is visible at 100%, but overall Nokia's full-resolution output still looks pretty good.
When we convert the DNG file with both color and luminance noise reduction set to zero, it becomes clear how much noise is in the image. There is a lot of grain and color blotches, but the image also looks a touch sharper. Increasing the color noise reduction to 25 gets rid of most of the color noise, but preserves most of the detail. However, the 1020's JPEG engine is doing a decent job at higher ISOs and the additional amount of detail you get through Raw processing is limited.
We also produced a "clean" version of the Raw file by setting luminance noise reduction to 45, in addition to the color NR. The end result is not too dissimilar to the out-of-camera JPEG, albeit with a little less sharpening applied.
We went through the same procedure as above with an ISO 1600 DNG file. We had to set the Lumia to manual ISO to make it capture this shot in a dimly illuminated gallery at ISO 1600. As you can see the out-of-camera JPEG is pretty clean, but also a little soft. It's obvious that low-contrast detail is being lost through noise reduction. With all noise reduction set to zero, chroma noise becomes very intrusive - but you can see that some additional low-contrast detail is hiding behind all the noise.
Again, applying some color noise reduction eliminates all the chroma noise and generates an image with good detail but a lot of grain. Reducing the grain by increasing luminance noise reduction makes the image look cleaner, but swallows some low-contrast detail and generates an overall softer look.
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