ISO Sensitivity / Noise levels (contd.)
In-camera High ISO noise reduction
Despite its mid-level ambitions, the NX10 offers only a simple On/Off option for High ISO noise reduction - whereas we'd usually expect to see a couple of levels, to allow people to tailor the JPEGs to their own tastes. The option only acts at ISO 3200 and offers additional noise reduction (the 'off' setting doesn't mean that no noise reduction is being applied.
As can be seen from the graphs, High ISO NR has no effect at ISO 1600, acting only at ISO 3200. It affects both luminance and chroma noise but affects the latter to a greater extent.
|High ISO NR Off||Night ISO NR On|
As the graphs showed, the biggest impact of applying the NX10's High ISO noise reduction is a decrease in chroma noise, with the colored blotches in the left-hand crops being effectively removed.
Noise reduction and fine detail
The biggest issue with noise reduction - especially luminance noise reduction - is that in the process of blurring away the noise it can also have a very destructive effect on the detail in an image, particularly the fine, low contrast detail you might find in hair, fur or grass. To better judge the effect on fine detail lost due to noise reduction we have shot our lovely model and produced crops from the feathers in the image.
|To check the effect of noise and noise reduction on low contrast detail we shoot our new studio setup at various ISO and noise reduction settings, then crop an area that's challenging to any camera. The very fine detail in the feathers will help to better judge the effect of noise reduction on fine detail.|
Raw vs in-camera JPEG noise reduction low contrast detail comparison
The noise reduction being applied by the camera's JPEG engine is affecting the very lowest-constrat detail even at base ISO - there's clearly more detail in the brown regions at the top right-hand corner of the ACR crops. This smudging of fine very low contrast detail manifests itself when the camera attempts to represent the texture of skin (so don't expect very close crops or poster-sized prints of faces to look terribly flattering).
At ISO 400 and above, the noise reduction starts to affect the fine detail and it becomes rather indistinct. By the time the additional, optional High ISO noise reduction kicks in at ISO 3200 there's very little fine detail for it to impact on (though turning it on wipes out anything that's left).
|ACR RAW NR OFF||JPEG High ISO NR OFF||JPEG High ISO NR ON|