We are continuing our in-depth evaluation of the sRAW format and this time we want to compare noise performance of sRAW when compared to down-sampling / resizing of images in post-processing software. Since Adobe’s Camera RAW processes high ISO RAW images and especially the sRAW format quite poorly, I used Nikon’s Capture NX-D software instead. The results are quite interesting, showing pretty decent implementation of in-camera resizing and noise reduction. For this study, I only exported high ISO images above ISO 800.
As expected, ISO 800 is very clean on both, showing no signs of noise. The image from the RAW file looks a bit sharper as a result of different down-sampling algorithm used by software.
ISO 1600 adds a little bit of noise and it looks very good as well on both.
Pushing to ISO 3200 also yields quite good results, with similar noise levels.
At ISO 6400, noise patterns start to change on both. Still hard to say which one looks better, although the detail level on the RAW file appears better.
At ISO 12800, we see the difference in noise between RAW and sRAW. Interestingly, sRAW actually looks cleaner in the shadows.
And sRAW certainly seems to take over at ISO 25600, yielding cleaner images with less artificial colors.
The last boosted setting of ISO 51200 also demonstrates better in-camera down-sampling of sRAW when compared to software RAW down-sampling.
sRAW Noise vs Down-Sampling Conclusion
Seems like Nikon did a good job with the re-sizing / down-sampling of images when creating sRAW files. Looking at the above image samples, the sRAW format yields very similar results below ISO 12800 and superior results in all other cases. The images from the RAW down-sampling process look a bit sharper, but that’s because of the differences in resizing algorithms. If one were to apply some sharpening in NX-D / ACR, those sharpness differences would certainly diminish, although they could add a bit more noise if not done right.
Sadly, Adobe Camera RAW 8.6 is quite poor at rendering high ISO images from the D810. And if you use sRAW, Adobe silently applies negative exposure compensation. I really hope Adobe will address these issues in the next release.