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#apertus IRC Channel Logs

2014/07/17

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Bertl
off to bed now ... have a good one everyone!
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07:34
Topic
apertus° - open source cinema | www.apertus.org | Currently Hot: AXIOM Beta https://apertus.org/axiom-beta | IRC Logs available at: http://irc.apertus.org
07:34
se6astian
has set the topic
09:03
FergusL
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10:53
se6astian|away
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11:13
se6astian
good day!
12:04
Bertl
morning folks!
13:52
danieel
interesting price on the pocket bm camera...
14:00
se6astian
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14:25
Bertl
danieel: how so?
14:25
danieel
dropped to half till end of sept
14:26
danieel
end of august
14:27
Bertl
so price dumping again, I presume
14:30
Bertl
I'm curious what message this sends to customers in general
14:31
Bertl
for exisiting: look, we charged you twice the amount for the same camera a few months ago :)
14:31
Bertl
for new ones: hey, we can't sell the product, so we half the price now :)
14:32
Bertl
or maybe it is a completely different message
14:33
danieel
they maybe do something better (gs, hfr) and those stocked units wont be sellable
14:34
danieel
but i assume there wont be any big announcement at ibc
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se6astian|away
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se6astian
time for bed
22:04
se6astian
night night
22:04
se6astian
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23:00
FergusL
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23:01
troy_s
Egads.
23:02
troy_s
When did the Black Magick camera drop to 500$?
23:02
troy_s
Erf.
23:10
danieel
few days back
23:10
danieel
july 16th is the news announcement
23:10
troy_s
Crazy.
23:10
danieel
what do you think of it ?
23:11
troy_s
I'm not a fan of the cameras due to the smaller sensor and the lack of offspeed, but at 500$ it's damn tempting.
23:11
troy_s
My axes of evaluation for this camera are:
23:11
troy_s
1) Latitude and format (both a win - raw Bayer and latitude are pretty decent)
23:11
troy_s
2) Sensor size (a loss here)
23:11
troy_s
3) Off speed (a loss here)
23:12
troy_s
But when I look at all three and then compare price... it makes for an actual decision.
23:12
danieel
resolution is poor.. (fhd@bayer)... even the F3 got enough cells to produce fhd 4:4:4
23:12
troy_s
(at 1000$ it is ridiculuous)
23:12
troy_s
?
23:12
troy_s
What's the price on the F3?
23:12
troy_s
(Haven't seen it. Is it a Sony?)
23:12
danieel
not comparable, as for the rest of the features
23:13
danieel
i think that there is no other camera which relies on pure fhd bayer sensor today..
23:18
troy_s
danieel: It's a pretty damn good camera at that price
23:18
troy_s
for what it is. The balance is pretty damn reasonable.
23:19
troy_s
The photosites still resolve to the lens which is always going to be an issue for CMOS.
23:19
danieel
what issue?
23:21
troy_s
Well the lens is going to resolve down across a smudge of G/B/R sites
23:21
troy_s
and we will always be facing the reality of missing data
23:21
troy_s
(Unless we go to a CCD or such)
23:21
troy_s
make sense?
23:22
danieel
does not. the ccd is same bayer pattern as cmos
23:22
troy_s
Some CCDs I thought were stacked
23:22
troy_s
But perhaps I am mistaken
23:22
danieel
for stills only (foveon)
23:22
troy_s
I know there were a few sensors out there based on that model
23:22
troy_s
Ah well, you get my point.
23:23
troy_s
(hopefully)
23:23
danieel
they recently went on to loose some of that stacking to increase luma resolution, colors get subsampled
23:23
danieel
the stacked ones can not yet be used for video.. so that is not a point
23:23
troy_s
Interesting. Those sorts of sensors would introduce a film-like crosstalk.
23:24
danieel
crosstalk is just a shifted color space, can be restored or enforced by the 3x3 matrix..
23:25
danieel
i do not like the bmpcc's rolling shutter... even that latitude is great, the yello efect ruins practical use
23:25
troy_s
danieel: Not really
23:25
troy_s
(agree on shutter)
23:25
troy_s
But crosstalk is a very real concern in VFX land
23:26
danieel
explain more in depth, that intersts me
23:26
troy_s
hence why keyers almost always want to be operating on the raw camera "space" (not that a camera really has a space per se)
23:26
troy_s
Well a non-crosstalked set of data has some nuances to it that are smudged apparently when you take it into a different transform.
23:26
danieel
isnt it confused then with a color subsampling? (usually you get 422 out of cameras)
23:26
troy_s
(for example, you and I might be able to pull a key using the edge information strictly from a luminance pass across the raw bayer)
23:27
danieel
that is unusual
23:27
troy_s
It makes sense though
23:27
troy_s
The lowest to the steel data you get of the lens resolving to some data
23:27
troy_s
is in that raw bayered image
23:27
danieel
(recently saw some pro bw photographer who pulls bw shots from raw stills)
23:27
danieel
ah
23:27
troy_s
And as soon as you debayer you are 'smudging' that
23:27
danieel
i get it where the issue comes from
23:28
troy_s
the difference between what is captured (critical for keying) and what color it represents is blurred
23:28
troy_s
(literally I suppose :) ()
23:28
danieel
when you apply 3x3 matrix / arbitrary "crosstalk", then you are corrupting the physical position of pixels
23:28
troy_s
Bingo
23:28
danieel
as the input elements are sampled at different pos
23:28
troy_s
Exactly.
23:28
troy_s
So your citing goes to shit
23:28
danieel
good, finally what we agree both on :)
23:28
troy_s
(I thought we agreed often. Communication sucks.)
23:28
troy_s
(Little did I know)
23:29
danieel
:)
23:29
troy_s
(Citing is actually a huge issue in subsampling anyways)
23:29
danieel
both have our set of truth
23:29
danieel
citing?
23:29
troy_s
(IIRC Greg's work on "Toward Better Subsampling" covered that a bit)
23:29
troy_s
Citing
23:29
danieel
whats that?
23:29
troy_s
where the given sample lay in spatial sense
23:29
troy_s
If you think of a standard lerp
23:29
troy_s
the interpolated value rests precisely at 0.5 distance
23:29
danieel
lot of new words today.. lerp?
23:30
troy_s
LERP == Linear Interpolation
23:30
troy_s
Hrm. How to describe.
23:30
troy_s
Think of it this way
23:30
troy_s
Think of three pixels
23:30
troy_s
expressed as a bar graph
23:30
troy_s
looking at the side
23:30
troy_s
when we draw a line from the middle of the first bar graph to the third
23:30
troy_s
the line precisely crosses the middle of the middle bar graph at the midway point
23:31
troy_s
A cubic scale
23:31
troy_s
will create a curve that doesn't quite end up precisely at that mid point - the citing is off.
23:31
troy_s
(As for tents, box, Lanczos, Sincs etc.)
23:32
danieel
so this is upsampling of the subsampled color channels, where they do not match? got a little lost
23:32
troy_s
Yes
23:32
troy_s
upsampling and how that RGB set is generated
23:32
danieel
and that error multiplies by consecutive color transformations
23:33
troy_s
http://www.glennchan.info/articles/technical/chroma/chroma1.htm
23:33
troy_s
Exactly.
23:33
troy_s
Glen's work has pictures!
23:33
troy_s
It's great to look at as some issues that are obvious become clear, despite rarely entering one's world view.
23:33
danieel
(that is why i preferred to keep my stuff in DNG... it keeps bayer, unless other formats)
23:33
troy_s
Sure.
23:34
troy_s
But at some point you have to futz with crap in RGB
23:34
troy_s
or a tri-color world
23:36
danieel
btw how would you deal with moare? strong sw - adaptive processing, or just proper OLPF?
23:36
troy_s
God that's a huge question.
23:36
troy_s
I know that the typical method goes as follows that I have seen:
23:36
troy_s
1) Filters on lens. Smudge it. Likely not preferred by some.
23:36
danieel
have noticed that f5 or f55 has a set of olpf for different uses
23:36
troy_s
2) Change the goddamn thing.
23:36
troy_s
(as in if it is wardrobe, change it.)
23:37
troy_s
that's the reality I have seen
23:37
troy_s
Yes. There's filters.
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