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Author Topic: Srgb to linear to logC to rec709  (Read 2741 times)

fredjeang2

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Re: Srgb to linear to logC to rec709
« Reply #20 on: December 02, 2017, 09:09:45 PM »

Using a control surface with Resolve and ACES is very usable.
Also, I don't know if you found that too but the feel of the log wheels
Sort of brings me naturaly towards a different approach I could call
Undirect. In the sense that I tend to obtain one tone not directly but
With 2 or more nodes, using complementaries. (Or secondaries in english?)
I find that it often gives more control and reminds me a bit of painting.
One color canceling the other but not completly. Each node involved
With the same low-high range where I’m looking for the tone to be applied.
It's more nodes but not as "brutal” as trying to obtain the color directly.

And I see also that all (absolutly all) consumer cameras and even the GH lines and
The Sony are no fun to grade, with the exception of the BM pocket.(talking about small cams)
Not only a mater of log and DR But many times, the look is so clinical, antiorganic
(Or should I say videoish) that I have no pleasure to work with those and it takes
Much more weired tricks to get where I'd like to than with Red; and in the end never
Satisfying. I even prefer what delivered the old 5D mk2, despite low bitrate and FHD reso,
But Canon color science is quite good with skin tones right out the box.
I think that for a filmaker on a budget, BM cameras are the best and not one dslr or mirrorless
Cameras that end to be problematic and cost much more to rig.

...and oh yeah...menus! That could be the title of the most absurd novel
On digital imagery. Cameras that lack proper codecs but yes...menus everywhere.
Hidden, not so hidden...a bliss.
150 pages of useless menu: what a thrill!

Slog2, Slog3...in the end there are artifacts everywhere that don't exist
With a simple Prores 422 out the old BM pocket. And the BM Cine delivers
Great usable footage right out the box.
Pana does a fantastic job with its GH line and the Gh5 seems
A huge step forward, but I never liked their colour science. Maybe
It's me.

I think that until Raw will not be a common feature in all video
Capable cameras, there will be an enormous disorder.
« Last Edit: December 02, 2017, 09:45:33 PM by fredjeang2 »
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smthopr

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Re: Srgb to linear to logC to rec709
« Reply #21 on: December 03, 2017, 12:46:43 PM »

Also, I don't know if you found that too but the feel of the log wheels
Sort of brings me naturaly towards a different approach I could call
Undirect. In the sense that I tend to obtain one tone not directly but
With 2 or more nodes, using complementaries. (Or secondaries in english?)
I find that it often gives more control and reminds me a bit of painting.
One color canceling the other but not completly. Each node involved
With the same low-high range where I’m looking for the tone to be applied.
It's more nodes but not as "brutal” as trying to obtain the color directly.

And I see also that all (absolutly all) consumer cameras and even the GH lines and
The Sony are no fun to grade, with the exception of the BM pocket.(talking about small cams)
Not only a mater of log and DR But many times, the look is so clinical, antiorganic
(Or should I say videoish) that I have no pleasure to work with those and it takes
Much more weired tricks to get where I'd like to than with Red; and in the end never
Satisfying. I even prefer what delivered the old 5D mk2, despite low bitrate and FHD reso,
But Canon color science is quite good with skin tones right out the box.
I think that for a filmaker on a budget, BM cameras are the best and not one dslr or mirrorless
Cameras that end to be problematic and cost much more to rig.

...and oh yeah...menus! That could be the title of the most absurd novel
On digital imagery. Cameras that lack proper codecs but yes...menus everywhere.
Hidden, not so hidden...a bliss.
150 pages of useless menu: what a thrill!

Slog2, Slog3...in the end there are artifacts everywhere that don't exist
With a simple Prores 422 out the old BM pocket. And the BM Cine delivers
Great usable footage right out the box.
Pana does a fantastic job with its GH line and the Gh5 seems
A huge step forward, but I never liked their colour science. Maybe
It's me.

I think that until Raw will not be a common feature in all video
Capable cameras, there will be an enormous disorder.

Shooting sLog with the sony cameras really requires a better codec than what is found in the little cameras (I don't know about the bigger, more expensive Sony professional cameras)  An off board recorder with 10 bit 422 recording is a minimum for sLog.  And then, the cameras work quite well, but are not so small anymore.
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Bruce Alan Greene
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fredjeang2

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Re: Srgb to linear to logC to rec709
« Reply #22 on: December 14, 2017, 06:54:16 PM »

About wheel sensitivity:  Are you using a control surface?  Or just the mouse?

I you are using a control surface (the contraption with the balls and wheels), in Resolve preferences there are settings for the sensitivity of the wheels and that should solve your issue.  Mouse control of the GUI wheels in Resolve is often too coarse.

About gamma 2.6 that you mention, it just applies to DCI/P3 color space.  If you're not grading with a projector display, I don't think this is relevant anyway.  Using a control surface with Resolve and ACES is very usable.  But in ACES (or any Log grading), get very used to adjusting the "low range" and "high range" adjustments that determine what part of the curve these operations work on.
I finaly discovered the reason of this unfamiliar behaviour of the log wheels I experienced and now everything's back on track fortunatly.
The fact that I was using on trip a laptop that had an antique version of Resolve (11) I did not bother to upgrade with no ACEScc nor cct available.
Now on #14 and the wheels work just as they should do, even with the mouse. It was as simple as that.
Cheers.
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bcooter

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Re: Srgb to linear to logC to rec709
« Reply #23 on: December 14, 2017, 07:27:50 PM »

I finaly discovered the reason of this unfamiliar behaviour of the log wheels I experienced and now everything's back on track fortunatly.
The fact that I was using on trip a laptop that had an antique version of Resolve (11) I did not bother to upgrade with no ACEScc nor cct available.
Now on #14 and the wheels work just as they should do, even with the mouse. It was as simple as that.
Cheers.

On the road, even sometimes in studio, I run 12.5 on a macbook pro and set at a lower display resolution, it runs fine.   In fact I've graded so much with a mouse, even in studio I sometimes don't bother to hook up the board.

IMO

BC

John Brawley

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Re: Srgb to linear to logC to rec709
« Reply #24 on: December 22, 2017, 05:53:31 PM »

This probably silly topic perfectly reflects my current ignorance when it comes to
Understand color science in the pipeline.

The question I ask is if it would makes sense to linearize an srgb material of a consummer camera then apply an Arri logC lut then ArrilogC to rec709 lut.

What I have in mind is this:
- 1 scene shooted with an Alexa in logC
- the same scene shooted from a different angle with a fuji with a look applied from capture in camera.
2 different animals for the same shot.
I'd like the Fuji footage to behave as if it had been shooted by the Arri logged.
So when I apply a logC-to-rec709 to both I got consistency.

In short, the idea is first to cancel in post what the Fuji in-camera did.
Then simulate the curve of the Alexa as if...

Does it make sense?

I doubt you will achieve that because...the fuji isn't an Alexa. It's never going to look the same. Simply transforming the space and linearising it and applying a LOGC curve doesn't make it an Alexa. 

But some colourists do like to do a version of what you're saying. Like Juan who I've linked to below.

I think this is the closest you may get, and you're basically using the OFX plugin's to do the transforms.  Be aware that simply applying a LogC LUT applies a matrix and gamma gurve to footage and it will be expecting colours form an Alexa.  You feed it fuji colours and something will go wrong for sure.  Using this method you're bypassing at least applying the wrong matrix.



JB

« Last Edit: December 22, 2017, 10:27:55 PM by John Brawley »
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