Since I cannot get Resolve to match the ACES linear files from RawViewer
to the original mxf files (and the colourist refuses to set up Resolve
with ACES), my workflow now seems to become the following (not that I am
a fan, but it might have to do):
-export a bunch of frames from the film (including a test chart) from
Resolve as log dpx
-export the same frames as ACES linear from RawViewer
-in Nuke, create a sequence for each (AppendClip or Switch node with
expression)
-use those two clips as inputs to the MatcGrade
-set a key frames on each frame, analyze and export a 3d lut.
The resulting lut is applied to the output in Nuke just before rendering
log dpx files for final grading in Resolve.
This way I'm getting very close to making the VFX plates match the
original mxf raw files. It's not perfect, but probably good enough in my
case.
Needless to say that I'd prefer a less empirical way, but this seems to
be the only workable solution so far.
Cheers and thanks again for all your help Alex!
frank
On 3/7/14, 6:22 AM, Alex Fry wrote:
They would just be updating/improving their IDT.
I've tried the current one, and it work's fundamentally as expected.
But like any sort of calibration exercise, you can always get closer
to the target with more time.
On Fri, Mar 7, 2014 at 4:05 AM, Randy Little <[email protected]
<mailto:[email protected]>> wrote:
I just saw that at NAB Sony is releasing an update to there ACES
implementation as well as s-log3 for the f65. So Maybe they had
something that wasn't quit right with their ACES implementation?
Randy S. Little
http://www.rslittle.com/
http://www.imdb.com/name/nm2325729/
On Thu, Mar 6, 2014 at 11:51 AM, Alex Fry <[email protected]
<mailto:[email protected]>> wrote:
The ACES values are scene linear.
The difference with scene linear files you would have
previously been working with, is that whilst they would have
been scene linear in their intensity, but their primaries are
effectively display referred (either Rec709 primaries or P3).
Because their gamut and whitepoint already match your display
device a simple 1D transform will give you a viewable result.
ACES stores values using the much wider primaries shown below,
they are wide enough that they cover all of the visible
colours in the horseshoe of the spectral locus.
When you look at the Yxy diagram below, you have to remember
that big Y/brightness (the intensity of the pixel) is
collapsed into the Z axis, so you have to imagine it coming
out of the screen towards you.
The scene linear files you would have used in the past can
only represent colour within the green or blue triangles, ACES
can represent colours across the entire spectral locus (plus
some imaginary colours outside the horseshoe but within the
ACES triangle). But the total sum brightness, and its
linearity relative to light levels in the scene remain the same.
I was under the impression that one of the main points of
ACES is to use the linear light state as the common ground
for all colour qworkflows
It is.
And part of that is divorcing the primaries from either the
input device or output device.
Inline image 1
On Thu, Mar 6, 2014 at 10:19 AM, Frank Rueter
<[email protected] <mailto:[email protected]>> wrote:
Thanks.
Using OCIO and RRT (sRGB) yields the expected result. I
guess my confusion was/is with the fact that ACES linear
does not produce the result I expected from scene referred
linear data, and I was under the impression that one of
the main points of ACES is to use the linear light state
as the common ground for all colour qworkflows, as it
should represent the light data captured on set irrelevant
of input output signals.
In other words, I would a have expected ACES linear to be
a lot closer to the linear light images I have been
working with over the years.
It may just be a case of un-learning things to be able to
understand this fully.
Cheers,
frank
On 3/6/14, 8:17 AM, hxpro wrote:
On 03/03/2014 19:52, Frank Rueter wrote:
Actually, scratch that, ACES linear followed by
rec709>linear in Nuke
doesn't look like anything I see in RawViewer in
terms of saturation.
The gamma looks reasonable though.
Any more hints?
ACES uses very saturated primaries (in chromaticity
terms), this means that just performing a 1D colour
space conversion will result in desaturated looking
images. You need to use something like the RRT+ODT to
convert to something 'filmic', or at least you need to
map from the ACES primaries into the rec709 primaries
somehow. You'd need to be careful doing so due to
gamut missmatches, which is where a lot of the
challenges are.
Kevin
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