In-camera processing of long-exposure RAW data

Started Jan 21, 2010 | Discussions thread
OP Marianne Oelund Veteran Member • Posts: 7,779
Nikon have declared zero equal to zero
1

kyklops wrote:

reading this story I must raise the followup question (yes I do shoot Canon:-) if the "raw cooking" in Nikon cams is limitd to longer than 1/4 exposures. I have seen lots of claims of Nikon "cooking" black level clipping too in their cams, irregardless of shutter speed.

There is no processing of RAW data related to black level, i.e., there is no artificial black clipping added. Nikon set the DN=0 level to be at the analog 0V level. However, since noise is bipolar (averages to 0, but swings both above and below), half of the noise is suppressed (truncated) when the A/D converter assigns DN=0 to negative voltages, and there is no signal present (black frame).

In blacks or very dark shadows, the noise truncation produces a false signal since the remaining noise no longer averages to 0. We're talking about a very small signal, though, and most users would never notice it. It's of interest to those who study sensor performance, and a few critical users such as astrophotographers who are trying to stack images, etc.

These clean D3s images, are they only the result of Nikon hex brews????

Sensor data from the D3S is consistent across the ISO range, and the signal range, and does not show evidence of post-processing effects (for shutter speeds of 1/5 sec or faster).

Of course if you eliminate all "" abborrations "" in images and call it raw, what have you got???

In attempting to remove "hot" pixels, Nikon have actually created aberrations.

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