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#apertus IRC Channel Logs

2018/06/08

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supragya
hi BAndiT1983
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supragya
se6astian: are you available?
17:49
supragya
need your thoughts on PLR
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17:58
se6astian
yes, now
18:03
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supragya
.
18:38
supragya
se6astian: let me know (via email), how you think about this!
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20:21
supragya
hi g3gg0
20:33
se6astian
hi there
20:33
se6astian
just replied to your email
20:37
supragya
se6astian: these are A,B,C:
20:37
supragya
A) convert by hand to raw16-lin using probably a per-pixel-lut as alex proposed
20:37
supragya
B) just pass raw12-plr and provide the cdng tag for the lut
20:37
supragya
C) convert to 16bit in per pixel and apply a global lut/curve to reduce data to 12 bit
20:37
supragya
With illustrations/references do you mean GUI stuff for the camera operator to see while shooting (as we discussed some days ago)? - no
20:38
se6astian
then my vote is B)
20:38
supragya
i meant references in form of further reading
20:38
supragya
illustration as in graphs/etc
20:38
se6astian
I dont think A) is required
20:38
se6astian
and see no point in c)
20:39
supragya
B is explained in the model then
20:39
se6astian
I am good and need no further illustrations/references
20:39
supragya
(it is really not based on any proof)
20:39
supragya
need experimental evidence as you did with PLR experiments
20:40
g3gg0
hi supragya
20:40
supragya
However, as g3gg0 wanted me to dig deeper into this, I wanted to know what he really wanted (how deep, and in which direction)
20:40
supragya
hi g3gg0
20:40
g3gg0
just came home from a canoe event
20:41
supragya
just came back to PC seeing you online on irc logs XD
20:41
se6astian
I know alexML already started with the math model but I am not even convinced we need one, we can just measure the sensors response curve with as many samples as we desire and create a LUT from it
20:41
g3gg0
yeah A/B/C
20:42
g3gg0
iirc my idea was to look into effort needed for each A) and B)
20:42
g3gg0
A is comparable to C in the means of: pixel processing during DNG conversion
20:43
g3gg0
B is a low hanging fruit, if it is easily possible to forge a DNG which has the LUT *and* tools can read it
20:43
supragya
I am not sure on how to visualize on converting 16bit with global lut to 12bit
20:43
g3gg0
having features in a standard, doesnt mean that all tools support it
20:43
g3gg0
you mean C?
20:43
supragya
yes
20:43
BAndiT1983
why 16bit to 12?
20:44
BAndiT1983
sensor delivers 12 already
20:44
g3gg0
wasnt this your proposal? or danieel
20:44
supragya
best i could think was a gamma curve, but that's non linear
20:44
g3gg0
12 (PLR) -> linearize to 16 bit -> downconvert to 12
20:44
supragya
g3gg0: :)
20:44
supragya
this was danieel's
20:44
BAndiT1983
why convert it down again?
20:44
BAndiT1983
besides problems to display that range, there is also processing error involved
20:44
supragya
12 -> 16 -> 12 (I don't get what's going on)
20:44
g3gg0
you cannot linearize 12->16 without having a bunch of useless noise
20:44
supragya
12 -> 16 makes sense
20:45
g3gg0
wait
20:45
supragya
16 -> 12 why and how
20:45
BAndiT1983
12bit thourgh linearization table to 16 bit
20:45
BAndiT1983
at least that there the things i saw in other cinemadng files
20:45
BAndiT1983
i'm not an expert, but that seems like proper way
20:45
supragya
B makes sense...
20:46
BAndiT1983
go for B at the moment, no need to do things complicated
20:46
g3gg0
as said, C is more or less like A, just with a downconverison to 12 bit. so...
20:46
g3gg0
its just an extra step
20:47
BAndiT1983
can someone point me to papers or something like that, which describe this downconversion
20:47
supragya
g3gg0: could you look at my notes (i sent you)
20:47
g3gg0
thats why i said A and C are similar
20:47
supragya
to linearise, we need >12bit space isn't it?
20:47
BAndiT1983
still see no point in losing data, with proper debayering it would be no problem with noise, especially with dark frame
20:48
se6astian
supragya: to linearise, we need >12bit space isn't it? <- yes
20:48
supragya
so compressing things back to 12bit is losing data, or am I wrong?
20:48
se6astian
the more bits the better
20:48
g3gg0
maybe you should discuss it with danieel ;)
20:48
se6astian
supragya: so compressing things back to 12bit is losing data, or am I wrong? <- correct
20:49
supragya
so why is C even a consideration when we talk RAW?
20:49
supragya
for JPEG i could understand this, but isn't our priority needs to be to save as much detail as possible?
20:49
g3gg0
also in canon raw video we use only 12 bits instead of 14 bits, as the two bits are partially noise
20:50
g3gg0
and the reduction in bandwidth is noticeable
20:50
supragya
so C is perhaps "smoothing out" to accomodate ?
20:50
BAndiT1983
that can be done in post
20:50
BAndiT1983
capture everything you can and let the whole processing stuff for post
20:50
supragya
in anycase, bandwidth is issue between camera and PC
20:51
supragya
and that is always 12bit, be it a,b or c
20:51
g3gg0
why focus on this C now?
20:52
supragya
Just because I am not able to understand it's use case, and the mentality behind it
20:52
g3gg0
16->12 is just an option that can be added, ignored or whatever :)
20:52
supragya
nothing more than that ;)
20:53
g3gg0
ok, then simply flag it as "well, someone might think that the 2 bits less data is a good option without losing any useful information" ;)
20:53
g3gg0
might be, might not.
20:53
supragya
so, B?
20:53
BAndiT1983
that has to be tested in practical way
20:53
g3gg0
i'd leave it as an non-verified idea
20:54
BAndiT1983
go for general 12bit from sensor and curve for linearization to 16 bit or so
20:54
g3gg0
there are people who are far more skilled in matlab and alike than me to test this ;)
20:54
BAndiT1983
it's about the range, so one can teak the colors and exposure in tools
20:54
g3gg0
@supragya: please look into it, what you need for that
20:54
BAndiT1983
*tweak
20:55
supragya
se6astian: could you shed light on how B's LUT could be found experimentally?
20:55
g3gg0
check what a DNG needs for the LUT, like the tags etc
20:55
BAndiT1983
some examples were posted yesterday
20:55
supragya
g3gg0: should be a general header preceeding a LUT structure
20:55
BAndiT1983
tag 51720 or something like that and a nsippet for curve
20:55
supragya
I would need exiftool analysis
20:56
supragya
and hex too.
20:56
BAndiT1983
is it just DNG specific stuff or is it also used for TIFF?
20:56
supragya
LUT?
20:56
supragya
LUT is general
20:56
BAndiT1983
tag -> https://docs.google.com/document/d/16m2uaoY_YvpRwvpQeH_zCoyBlyvtFFi_UWSDglrk62Y/edit#
20:56
supragya
but tags depend on the format
20:56
BAndiT1983
sorry, wrong link
20:56
BAndiT1983
https://www.adobe.com/content/dam/acom/en/products/photoshop/pdfs/dng_spec_1.4.0.0.pdf
20:56
BAndiT1983
tag 50712
20:57
supragya
that is understood
20:57
BAndiT1983
and it points to chapter 5 for further info
20:57
supragya
that a paragraph :)
20:57
supragya
in chapter 5
20:57
supragya
of what linearisation "is"
20:58
BAndiT1983
linearization also used for encoding to store less values
20:58
g3gg0
50712 - DNG/LinearizationTable
20:58
BAndiT1983
interesting how others do it -> http://lclevy.free.fr/nef/
20:58
supragya
i get the idea of process (LUT + 12bitPLR = 16bitLINEAR)
20:59
g3gg0
thats good :)
20:59
supragya
a need a struct of sorts with datatypes to understand how to add it to publisher
20:59
BAndiT1983
supragya, have you tried to implement DNG by hand first?
20:59
supragya
something, that we figured in AVI, RIFF when making the frameserver
21:00
supragya
BAndiT1983: no, g3gg0 said I don't need to
21:00
supragya
I plan on using their mlv2dng system
21:00
supragya
modified for us
21:01
g3gg0
yep
21:01
BAndiT1983
http://www.guillermoluijk.com/article/superhdr/index.htm
21:01
g3gg0
you can still manually forge the DNG
21:01
BAndiT1983
know this article for long time, had to use google translator or deepl to understand it a bit
21:01
g3gg0
e.g. get a DNG out of mlvfs and handcraft / add the table if you are comfortable
21:02
BAndiT1983
it was just a suggestion to get a hang of LUT stuff in darktable or so
21:02
supragya
g3gg0: btw, why did you wanted the mlv generated by AXIOMRawStreamHandler(generator)?
21:02
BAndiT1983
if the files comes out correct, even synthetic gradient or so, then it should be possible to let darktable/rawtherapee to read the linearization LUT and play around with it
21:04
supragya
BAndiT1983: seems plausible, however needs a working "publisher" to build upon
21:04
supragya
should not be a big deal, especially since we are reusing code
21:05
supragya
but first, let's make sure that synthetic frames (Emulation) are encoded correctly
21:06
supragya
should I move this way? BAndiT1983, g3gg0 ?
21:07
g3gg0
which way do you mean?
21:07
supragya
*go in this direction
21:07
supragya
first, let's make the emulation complete I mean
21:07
supragya
so that we are able to encode synthetic frames at least to CDNG
21:08
supragya
and then add LUT etc. ?
21:08
g3gg0
i'd start looking into what you have to add to the CDNG to have LUT added properly
21:09
g3gg0
as BAndiT1983 said, craft such a CDNG (with or without mlvfs) and check if it will properly render in common tools
21:10
g3gg0
according to danieel, davinci resolve should support it properly
21:10
g3gg0
(was it danieel?)
21:10
supragya
:) you forget often
21:10
g3gg0
getting old ;)
21:10
supragya
isn't davinci resolve paid ?
21:10
g3gg0
nope
21:10
g3gg0
free
21:11
g3gg0
(yeah it was danieel)
21:12
g3gg0
i doubt that having a cool PLR and LUT enriched CDNG is useful if there is only one tool which can read it...
21:13
g3gg0
so best is to check if all use the same interpretation of the standard
21:13
g3gg0
(e.g. check with adobe raw, lightroom etc)
21:14
supragya
LUT standards, you mean?
21:15
supragya
also, any CDNG files you have which I should begin hacking on?
21:15
g3gg0
yes. maybe the LUT format, as it is specified will be interpreted fine by every DNG reader. but still the file will not load due to dozens of other issues and missing tags
21:16
supragya
or mlv?
21:17
g3gg0
https://www.magiclantern.fm/forum/index.php?topic=11899.0
21:17
g3gg0
or your apertus MLV
21:17
supragya
you mean emulation?
21:17
g3gg0
yepyou can
21:18
supragya
okay.. thanks
21:18
g3gg0
yep, you can use a original canon mlv to get a proper DNG file using mlvfs, or just use yours
21:18
supragya
will look into it and report back
21:18
supragya
mine should work fine on mlvfs
21:18
supragya
or am I missing something critical which differs from canon mlv?
21:18
g3gg0
if mlvfs will work with your mlv files, it would be the best
21:19
supragya
let's look at that too.
21:19
supragya
Sure thing. Thanks for your time g3gg0, se6astian, BAndiT1983 :)
21:19
g3gg0
there were minor things. i think i asked you via mail
21:19
supragya
going to leave for now
21:20
g3gg0
e.g. frameSpace being set to 22008
21:20
supragya
ah yes,
21:20
supragya
that is probably a bug perhaps
21:20
g3gg0
ok
21:20
g3gg0
i'd also fill the raw_info properly
21:20
supragya
that was to be rectified or was a placeholder value
21:20
g3gg0
check a sample mlv file which values it uses
21:21
supragya
as I said, more of placeholder values to get the systems running
21:21
supragya
g3gg0: sure
21:21
g3gg0
iirc the active are etc are used
21:21
g3gg0
yep, cool
21:21
supragya
good night then :)
21:22
g3gg0
ok good night. will answer your mail tomorrow.
21:22
supragya
sure...
21:22
g3gg0
i like the proposal for the PLR block
21:22
nmdis199-
Hello g3ggo!
21:22
g3gg0
more details tomorrow. cya
21:22
g3gg0
hi nmdis199- :)
21:23
nmdis199-
Bertl, is busy with some stuff for few days so I'd need you and alexML :)
21:23
g3gg0
ok, i hope i can help ;)
21:24
nmdis199-
So, we were running some tests on beta and realized that many factors affected the run time of the code
21:24
nmdis199-
although, we did completed a bunch of tests we were planning to do more but unfortunately he got busy
21:25
nmdis199-
so, after talking to sebastian we have decided that I should write an overview of what kind of access is good/bad
21:25
g3gg0
ok
21:25
nmdis199-
I'll probably make a doc and will share with all my mentors, so I'd need your feedbacks :)
21:26
niemand
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21:26
nmdis199-
if you could look into it, it'd be amazing :)
21:26
nmdis199-
does that sounds right?
21:26
g3gg0
sure, you have my mail address? if not pm me
21:26
nmdis199-
no, I'll pm you :)
21:27
supragya
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21:28
nmdis199-
Thanks for your time, good night everyone!
21:29
g3gg0
sure, night!
22:36
se6astian
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22:36
BAndiT1983
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RexOrCine
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