Greetings!
Currently I'm editing 28 very noisy sports photos. They were all shot
outdoors under a heavy cloud cover, late in the afternoon near dusk, at
1600 ISO and a slow lens (F5.6 to F5.0) on a 15 mega-pixel camera,
(Canon 500D).
After I edited, and exported 4 of these photos to jpeg, I noticed
differences between the noise in the jpeg files versus what is seen in
darkroom.
I'm new to darktable, so I'm wondering if this might be user error!
For one of these files in question, I have a screen-shot of what
darkroom displays, as well as the jpeg, xmp file, and originating cr2
file available here,
https://www.dropbox.com/s/2wb2p3zzqokpnqg/denoise-differences.zip
(~22MB). (First time sharing via dropbox, so let me know if I've screwed
it up.)
For reference, the denoise tools that I've implemented are:
1. raw denoise – threshold 0.01, blend mode unbounded, opacity 100%
2. demosaic – amaze, edge threshold 0.003, color smoothing 2 times,
match greens full and local avg
3. denoise (non-local means) – patch size 3, strength 100%, luma 50%,
chroma 100%, blend mode unbounded
4. sharpen – radius 2, amount 0.5, threshold 0.5, blend mode off
The differences are subtle, but exist. In particular there are two
things I've noticed:
First,the noise seen in the pavement in the foreground and of the bumper
sides around the lower portion of the karts is smoother in darkroom (as
seen in the example screen-shot) than as seen in the jpeg. The zoom
level is 1.5:1, btw.
The second discrepancy is that in the jpeg there a couple of light dots
on the leading kart's bumper in the area in front of his rear wheel,
which are not seen in the darktable screen-shot.
Why is there a discrepancy between what is seen in darktable versus the
exported jpeg?
(I hope the answer is user error! :-) )
It will improve my work flow to understand this discrepancy.
Kind regards,
Ken
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