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#apertus IRC Channel Logs

2022/10/09

Timezone: UTC


07:03
balrog
left the channel
07:12
balrog
joined the channel
16:12
anuejn
vup: polyrhythm se6astian isnt there like pretty accurate spectral response in the datasheet of the image sensor?
16:12
anuejn
cant we just trust this data?
16:12
anuejn
at least for relative values?
16:14
vup
se6astian: can do later
16:15
vup
anuejn: maybe, it doesn't really specify errorbars
16:15
anuejn
could we 'just' derive all our color science from that
16:16
anuejn
or and why is that a naive thought
16:16
vup
So my assumption is they measured exactly one sensor
16:16
anuejn
vup: so no errors ;)
16:16
anuejn
quite plausible
16:17
se6astian
no idea tbh
16:17
se6astian
I wouldnt even know how to translate the response curve to a color interpretation
16:18
vup
Also it doesnt say anything about the response curve wrt intensity
16:20
anuejn
wrt intensity?
16:21
anuejn
but theoretically there is all the data to generate the two color matrices from this diagram if we assume that the sensor is perfectly linear?
17:15
aombk
left the channel
17:19
aombk
joined the channel
19:06
vup
Probably, although it could also be impossible
19:06
vup
(In general, regardless of the data we have)
20:00
anuejn
why or why not?
20:18
Bertl
it's impossible because it won't work with a matrix ;)
20:19
anuejn
what wont work with a matrix?
20:19
anuejn
like, you have to specify two matrices for the dng to be developed correctly
20:19
anuejn
for two different iluminants
20:20
anuejn
to map sensor output into CIEXYZ
20:20
Bertl
we already know, we need something more powerful than a matrix (or two)
20:23
anuejn
for nonlinear response of the image sensor?
20:25
anuejn
but even if we wanted to create something like a 3d lut, couldnt we just "simulate" test pics using the spectral response, the spectrum of some standart iluminant and the absorbing spectrum of our color targets?
20:30
Bertl
yes, in theory we could, we also need to take the lens into account though
20:31
Bertl
I was just commenting on the matrix part, hence the ';)'
21:20
anuejn
okay
21:49
anuejn
huh turns out you can have 3d luts in dng files
21:49
anuejn
but in a kind of odd form
21:50
anuejn
only in hsv form
22:21
anuejn
se6astian: do you have a link to the filter spectral response data for me?
22:22
se6astian
The uv it filters?
22:23
se6astian
*IR
23:00
anuejn
yup
00:44
anuejn
I obtained a pair of plausible color matrices from the datasheet spectral response :)
00:46
anuejn
(see https://github.com/anuejn/cmv12k_color_response/blob/main/color_matrices.ipynb)
00:50
anuejn
and it even kind of works in davinci resolve