ISO Sensitivity / Noise levels (contd.)

Noise reduction compared

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 at all NR levels (off, low, norm, high) 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 lovely model framed as shown here, with the new added feature of feathers. The very fine detail in the feathers will help to better judge the effect of noise reduction on fine detail.

JPEG noise reduction and low contrast detail comparison

The Nikon's high ISO noise reduction only kicks in at ISO 500, so, as you can see on the ISO 100 crops below, at lower sensitivities it has no effect at all. At ISO 800 the loss of detail at High setting is already clearly visible and it gets more pronounced as you go up the ISO scale. The default Norm setting appears to be the best compromise between retention of detail and noise reduction. While the Low setting gets rid of very little luminance noise (and thus shows good detail), the High setting is a bit too aggressive for our taste. If you want complete control over noise reduction though you'll be better off shooting RAW.

JPEG NR Off
ISO 100
JPEG NR Low
ISO 100
JPEG NR Norm
ISO 100
JPEG NR High
ISO 100
JPEG NR Off
ISO 800
JPEG NR Low
ISO 800
JPEG NR Norm
ISO 800
JPEG NR High
ISO 800
JPEG NR Off
ISO 1600
JPEG NR Low
ISO 1600
JPEG NR Norm
ISO 1600
JPEG NR High
ISO 1600
JPEG NR Off
ISO 3200
JPEG NR Low
ISO 3200
JPEG NR Norm
ISO 3200
JPEG NR High
ISO 3200
JPEG NR Off
ISO 6400
JPEG NR Low
ISO 6400
JPEG NR Norm
ISO 6400
JPEG NR High
ISO 6400

JPEG noise reduction and low contrast detail comparison

The D3X RAW files were converted using ACR 5.3 beta with all noise reduction set to zero. While they show marginally more detail than the 'NR Off' JPEG image there's also noticeably more luminance and chroma noise. If you're usually a JPEG shooter the tiny amount of extra detail you get from RAW won't make you switch to RAW. RAW gives you more control over noise reduction but having said that, the D3X JPEG noise reduction is already doing an impressive job.

ACR RAW
ISO 800
ACR RAW
ISO 1600
ACR RAW
ISO 3200
ACR RAW
ISO 6400