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ISO Noise / Noise reduction

One of the most impressive things about shooting with the DCS620x is exactly the reason Kodak created this camera, it's amazing sensitivity. With ISO levels starting at ISO 400 equiv., Kodak rate the camera as "calibrated" up to ISO 4000 and capable of ISO 6400. This means shooting in extremely low light / high shutter speeds. In reality I found the maximum amount of noise I was happy to "live with" peaked at about ISO 3200 (still a very commendable effort, indeed the most sensitive digital camera on the market).

The "standard scene" shown left was shot at very low light levels at various ISO's and then acquired with both noise reduction OFF and ON, crops of the same area from each image are shown in the table below, clicking on a crop display a medium/high quality JPEG of the acquire.

ISO Without Noise Reduction (OFF) With Noise Reduction (ON)
400
F9.0, 1.6 sec
500
F9.0, 1.3 sec
640
F9.0, 1.0 sec
800
F9.0, 1/1.3 sec
1000
F9.0, 1/1.6 sec
1250
F9.0, 1/2 sec
1600
F9.0 1/2.5 sec
2000
F9.0, 1/3 sec
2500
F9.0, 1/4 sec
3200
F9.0, 1/5 sec
4000
F9.0, 1/6 sec
5000
F9.0 1/8 sec
6400
F9.0, 1/10 sec

At first glance the noise reduction algorithm is definitely in the right "area", my personal opinion is that it's a little too much too early, several shots taken at high ISO's with acceptable noise were given the "oil painting treatment" by the noise reduction algorithm. In other instances leaving it on at moderate ISO's (ISO 800) produced a posterising (blurring) of detail which WAS NOT noise... The crops of images below shows slightly better exactly what I'm talking about.

Noise Reduction OFF Noise Reduction ON
ISO 3200, F2.5, 1/1000 sec
 
Noise Reduction OFF Noise Reduction ON
ISO 2000, F5.6, 1/25 sec
 
Noise Reduction OFF Noise Reduction ON
ISO 3200, F5.0, 1/100 sec
 

What Kodak need to do is fine tune their algorithm (or buy one from elsewhere) which can be set by the user in the TWAIN module to either "light / medium / heavy" noise reduction on a per-image basis.. It's almost as though the noise levels are lower than the noise algorithm is "expecting" and thus there's a tendency to lose detail on noise reduced images. Luckily Kodak have the option to correct this as noise reduction is performed either in the TWAIN acquire module or camera firmware (optionally).

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