D7100 'streaking'

Started Apr 7, 2013 | Discussions thread
Jack Hogan
Senior MemberPosts: 3,729Gear list
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Re: D7100 'streaking' - doesn't look like blooming or flare
In reply to krikman, Apr 9, 2013

krikman wrote:

I have seen no such thing.   In fact I have checked : the D7100's full SNR curves do not appear to show intensive (or any) noise reduction at ISO800 or 1600 in the Raw data.
Perhaps I will see differently once you share how you arrived at that conclusion and the data
that drew you to it.  Without this additional information, though, yours remains an unfounded, far-fetched claim without 'clear instrumental proving'.

DXO measures based on solid ground, but often have wrong interpretation. NR at hi ISOs performed not by blurring and smashing data from different photosites, (as works NR in post processing). It is kind of careful restoration and prediction of photosite measurings. It don't averages nearest pixels lightness, it averages color values by large blocks. So we had great color responce but no color details.

krikman, you may be able to but the rest of us can't eyeball this sort of stuff - we have to measure it.  If you feel that there is some noise reduction of whatever type happening at ISO 800, show us the numbers.  This is what I see in the green Raw channels near the spot of my previous post:

ISO 100 Mean (dark) 11.9 Stddev 1.25
ISO 100 Mean (light)  12.7 Stddev 1.20

ISO 800 Mean          97.2 Stddev 9.65

If I take the ISO 800 Mean and divide it by the average of the two ISO100 means I get an amplification of 7.9, pretty darn close to the expected 8.  If I now multiply the average noise at ISO 100 (1.25) by 7.9 I get 9.68 - pretty darn close to the measured value of 9.65 at ISO 800.

Where is the noise reduction of which you speak?

And if you need additional proving it would be tests at ISO 720 (with stripes and ISO800 with no stripes).

Yet again perhaps streaking has nothing to do with noise.  There are many operations that could be, and probably are, happening under the hood.

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