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#apertus IRC Channel Logs

2015/12/05

Timezone: UTC


00:14
arpu
left the channel
00:55
pozitron
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01:42
Bertl_oO
off to bed now ... have a good one everyone!
01:42
Bertl_oO
changed nick to: Bertl_zZ
03:31
intracube
irieger: interesting link, thanks
06:02
pozitrono
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07:40
pozitrono
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08:33
pozitron
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09:23
Bertl_zZ
changed nick to: Bertl
09:23
Bertl
morning folks!
09:43
intracube
morning Bertl :)
09:44
intracube
was the recent test footage run through motion interpolation software
09:44
Bertl
not that I'd know of, why?
09:45
intracube
can see some glitches that don't look like regular artefacts from debayering or regular processing
09:45
intracube
https://youtu.be/izDzFov3nDM?t=208
09:45
Bertl
well, I'm pretty sure youtube does their own recompression thing
09:46
intracube
it doesn't look like youtube compression
09:46
intracube
the side of the football has a weird patch on it
09:46
intracube
also a few frames later there's some even more weird stuff
09:46
intracube
will post a screencap in a mo
09:47
Bertl
you probably want to check with the raw data and/or se6astian|away when he wakes up
09:47
intracube
yup ok :)
09:52
intracube
couple of sample frames for se6astian : https://goo.gl/photos/QYggaXmfiQzKZpUK9 https://goo.gl/photos/zrMwj77c53dJVAft9
09:55
Bertl
doesn't even remotely look like data from the raw capture, so I'm pretty sure that was motion encoded (wherever that happened :)
09:58
comradekingu
Emulsion film?
10:03
Bertl
you can't go around and tell everybody about our secret :)
10:34
intracube
Bertl: yep, also some strong colour correction (for effect rather than correcting for sensor issues)
10:34
intracube
even though the video said footage was raw with no correction or compensations
10:34
intracube
which could be misleading
10:36
Bertl
as I said, no idea how it was processed, in any case I would check out the raw data, which should be available somewhere (se6astian will know)
10:37
intracube
yep
10:40
Bertl
from my tests, everything looks very similar to the alpha, the dynamic noise is definitely lower (probably due to the better design of the power supply)
10:40
intracube
I've had a quick look at the DNG files and they look neutral except for the pink highlights
10:40
Bertl
we have those strange artefacts on the right end of the sensor, which are unexplained yet (I suspect sensor register issues)
10:42
Bertl
colored highlights might be due to near IR or just the sensor profile (I presume the raw data is within the 12bit range)
10:43
Bertl
so a tint there is not unusual
10:43
intracube
have cmosis given an explanation for the artefacts on the right?
10:44
Bertl
not that I know of, but I'm unsure if it was properly reported yet
10:44
intracube
ah
10:44
Bertl
fact is, we have been seeing this on at least two different sensors (same model)
10:45
Bertl
we will shortly test with the engineering sample we used on the alpha, to figure out if it is caused by the new sensors (v2) only
10:46
Bertl
but to be honest, it could be caused by a lot of subtle changes done on the beta, so it definitely needs some more investigation
10:47
intracube
troy_s mentioned that the pink highlights was a known issue and this data would probably have to be clipped/ignored?
10:47
intracube
I noticed something similar on my Nikon DSLR when I enabled highlight recovery
10:47
intracube
(on the RAW software converter)
10:48
intracube
the image clearly had more highlight data, but it was skewed to pink/purple
10:48
intracube
istr that normally that data is ignored when outputting JPEGs or when converting RAW with highlight recovery disabled
10:49
Bertl
yes, of course, but this is to be expected
10:50
Bertl
"proper" raw data should not reach the lowest and highest values on each channel (for 12bit that is 0 and 4095)
10:50
intracube
it can be useful data in an emergency where footage would otherwise have to be junked
10:51
Bertl
otherwise the offset or gain is set wrong and clipping is to be expected
10:51
intracube
https://goo.gl/photos/JmwLbQMw2QqXgSmS9 (left: sample DNG, right: processed in Blender)
10:52
Bertl
yes, that's a good example, on the left, you see that neither black nor white is reached
10:55
pozitron
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11:04
pozitrono
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11:34
alexML
Bertl: the .raw12 file for that sample has lots of clipped blacks; in the DNG converter, I added an option to artifially raise the blacks in order to reduce color casts, but the sensor offset was way too low
11:35
alexML
(I'm talking about confettiTV-32.raw12, which appears to be from the same movie as intracube's link)
11:36
alexML
the "dark magenta" background from the left image is from artificially raising the black level
11:45
intracube
alexML: ah yep. I noticed the crushed blacks. I was expecting to see FPN and sensor noise in the darkest parts of the frame
11:45
intracube
but it was completely absent
11:46
alexML
yes, it's clipped
11:46
alexML
I wanted to see it as well, as I'm experimenting with FPN correction
11:54
intracube
I noticed similar black clipping on some of the footage from the alpha camera
11:59
Bertl
alexML: yeah, I think the reason for that is that with the live view, folks tend to make the blacks really black, but with the wrong adjustments
12:00
Bertl
i.e. either with the sensor registers or with the linearization lut, instead of the matrix or gamma lut (where it should happen)
12:41
irieger
intracube Bertl: You talk about the artifacts like in https://youtu.be/izDzFov3nDM?t=236 when meaning the artifacts on the right?
12:41
irieger
I
12:41
irieger
I'd take a "wild" guess and say some sensor params(read registers) could be tuned to match the used readout mode etc ;-)
12:42
irieger
alexML: what experiments do you do with fpn reduction?
13:07
Bertl
maybe, but we should have the "defaults" we used on the alpha
13:08
Bertl
nevertheless, more testing needs to be done
13:09
irieger
Yep, testing is always needed with this stuff. But to assure people I'd say it's not the sensors, it's the tuning of the sensor params and the software I'd say
13:11
alexML
irieger: I'm trying to find a way to estimate the FPN from any real-world image, since the optical black areas are way too small on this sensor
13:11
alexML
testing data (sample DNGs) welcome :P
13:12
irieger
Real world data? How about images of black? ;-)
13:12
irieger
I know, they don't show everything...
13:12
alexML
:P dark frames are very easy to fix, I already analyzed them in this thread: http://www.magiclantern.fm/forum/index.php?topic=11787
13:16
irieger
alexML: interesting. Have to look through this. So you (off course I knew who you are) took the stuff over to your forum. Bad guy ;-)
13:17
irieger
Thanks for ML btw. You are the reason I switched to Canon with their inferior sensor instead of Nikon when I jumped to Sony ship when it was clear they wouldn't make any more DSLRs ...
13:52
arpu
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15:16
intracube
highlight recovery + neutral grade test: https://www.youtube.com/watch?v=GTQzGedoxrc
15:58
se6astian|away
changed nick to: se6astian
16:14
troy_s
The transform should maintain some possible negative values for sensor noise.
16:16
troy_s
God I can't read that thread.
16:23
troy_s
intracube: Remember too (not that I know anything about the Beta, as I haven't worked on it yet) that the linear portion of the sensor doesn't carry through the full range of data (hence why when doing HDR merges software keeps a solid anchor in the linear portion). Any colour transform has to take this into account and nonlinearly adjust the data (hence 3D
16:23
troy_s
LUT).
16:24
troy_s
intracube: Most transforms vendors use are strictly a matrix, which is 'good enough'. A proper colorimetric transform for post production would ideally hold the proper XYZ values across the full range of data, and as a result, be a nonlinear transformation to avoid that colour casting you are seeing near the highlights. Hello rat piss yellow.
16:29
se6astian
changed nick to: se6astian|away
18:30
mithro
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mithro
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22:03
pozitrono
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rbckman
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rbckman
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