Exploring DNG from the Lumia 1520

Yesterday's post about the first shots from the Nokia Lumia 1520 was all based on Rafe Blandfords review with "snapshots" taken with the Nokia Lumia 1502. After publishing that, I learned Rafe had the raw DNG files available on his server as well, ready to download... Less than 24 hours later, I'm happy to present this new post from New-Zealand - by Bigley Ling

After posting my analysis on the latest 1520 pureview 5mp JPGs from Rafe, I was made aware there was full resolution DNG files to go with the pureview 5mp images. Extremely excited, I immediately downloaded and processed them using Photoshop. The results were a real eye opener. Not only was there a lot more detail, but also everything just looked finer and more detailed.

The obvious difference was the amount of visible noise. Using post processing techniques to remove noise in Photoshop, I was able to apply noise reduction sparingly to remove as much noise without turning the images into water color paintings. The RAW advantage also allowed me to apply my own personal touch when it came to contrast, saturation and color tone of the image.

Notice how the grass that was already very well rendered in the 5mp pureview image is now even more detailed when rendered to a full resolution. The much more controlled noise reduction is most obvious in the background grassed areas which now have texture and detail.

Where the branches intersect the sky, too looks significantly more detailed compared to the pureview 5MP version. Revisiting the soft corner issues that was noticed in the 5mp pureview versions, the full resolution processed from DNG version definitely amplifies this effect when inspecting the image at 100%.

As I mentioned in the introduction, the detail resolved from the 20MP sensor is really quite remarkable. Where the detail in the 5Mp pureview image was impressively clean, and defined, the full resolution processed DNG makes the 5Mp seem like a thumbnail when it comes to absolute detail.

This was in interesting case, since I did not realize the original pureview 5mp image was actually using pureview zoom. This would have an impact in image quality since there would be less to no oversampling taking place. Combine this with the lower light condition requiring a higher ISO320 would challenge not only the sensor, but also the image processing algorithms.

When comparing the output from the DNG vs pureview 5mp, the quality of the DNG is better, as more of the detail is preserved and the use of more conservative noise reduction means the resultant image will have a less processed water color appearance, but in turn will have slightly more grain.

Comparing the 5mp pureview vs bibubic reducing full resolution DNG JPG to 5mp.

This was an interesting test, and it is very subjective depending on how the DNG was processed in the first place. I took “shot 2” full resolution image processed from DNG and reduced it using bibubic reduction in Photoshop. In the past with 1020 images, I found applying post process bibubic reduction from the full resolution image gave far better results than the pureview interpolated in phone image. Comparing the photoshop interpolated 5mp image vs 5mp pureview in phone interpolated image had a surprising result.

What can be seen immediately is that the interpolated result from Photoshop is softer and less sharp than the pureview 5mp image. This time the differences in detail between the two images were minimal, and hard to depict. What this proves is that Nokia has finally refined not only the colors, when it comes to image processing, but also they have improved the overall oversampling algorithm. By applying a less sharpening than what we see on the 1020, the image seems more balanced and should appeal to both consumers and enthusiasts.

Conclusion
With the introduction of RAW DNG to high-end Nokia handsets like the 1520 and 1020 (coming soon), Nokia has expanded possibilities when it comes to high quality image capture. This suits phone camera enthusiasts as it will allow them the flexibility to tinker with an unlimited amount of image adjustments only limited by the program used to process the DNG.

What is a real surprise is the quality coming from this 20Mp sensor. Even at ISO 320, images rendered from DNG are highly usable for larger printing if need be. The only small let down is the corner performance, but if you know you need quality over the whole frame, just ensure you frame slightly further than you need to, which will allow for post cropping or reframing of the image.

The Pureview 5Mp oversampled image was put to the test today, when comparing it directly with a Photoshop interpolated equivalent. The results show that the Pureview oversampling engine that was previously unpredictable in the 1020 has now been fixed in Nokia black on the 1520.

Not only are colors more natural, but now textural detail is also preserved. The pureview 5Mp images now have a cleaner more detailed appearance, and best part for me is the green grass looks real. Although there is the option for capturing both DNG and 5MP, I suspect for casual social shots without zoom, the 5MP pureview images are that good, that the excess time required to process DNG may not be required. Not discounting the fantastic performance of DNG, but that can be left for more demanding scenes which require resolution and finer image adjustments.

The combination of Nokia Black firmware with the 1520 seems to be a match made in heaven. I suspect when Nokia black is released for the older more powerful 1020 camera, it should be the same, if not better. One just hopes it gets released sooner than later.

Bigley Ling, Christchurch, New Zealand.

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