Final Explanation of Gamma and Color Shift Problems

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tshansen

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Re: Final Explanation of Gamma and Color Shift Problems

PostWed Jun 03, 2020 1:48 pm

Trying to read up on the stuff in this tread. Alot of usefull information... but i still have one question. Why does my footage shift from slightly graded when importing to flat when cutting in it?

If i drop a file on my timeline, it looks somehow a little graded, but when i cut or make adjustment to it, part of the file becomes flat (like i shot it) and the rest is still graded? :roll:
This only happens with my gopro footage, not with my mavic air 2 footage or sony a6400 footage ?

https://drive.google.com/file/d/1RjEJ9x ... sp=sharing (a file to show what i mean)
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Re: Final Explanation of Gamma and Color Shift Problems

PostWed Jun 03, 2020 8:01 pm

Ok this thread has been super informative. I've got my renders matching the DV with QTX and VLC on my Mac Pro sRGB monitors. However on my retina P3 MacBook Pro I'm seeing something else. My rec709 and sRGB exports match in QuickTime, but seem dimmer, less saturated and lower contrast when compared with the sRGB export viewed in VLC. VLC now looks like the accurate image. What I'd like to know is what settings I should be using to target Retina P3 displays when rendering out previews for clients. So many P3 laptops and phones out there now.
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Dmitry Shijan

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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jun 04, 2020 1:43 am

VLC on macOS is not color managed. It use it's own internal color processing engine. It can read only Rec709, Rec2020 tags some HDR metadata tags, and can just transform video to Rec709 profile in very basic way. It will NOT transform video to Monitor color space similar to QuickTime. Not sure if VLC works correct with P3 displays. I didn't test how VLC works with P3 displays.
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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jun 04, 2020 2:34 am

Yes, I realize all of that. Which is why I was asking how I can create an export that will look more accurate in QTX on a P3 monitor, not why VLC was performing this way
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Dmitry Shijan

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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jun 04, 2020 2:52 am

Not sure what means "more accurate" Adjust gamma, contrast, saturation in Resolve. This is all about your grading skills and workflow.

Just do not use VLC player as a reference for colors on P3 displays.
VLC player is not color managed video player. It only for monitors with standard sRGB color space.
https://forum.videolan.org/viewtopic.php?t=149755
"ALL new macs ship with wide gamut dci-p3 displays.
VLC, even in the latest version 3.0.7 does not support mac color management, completely ignores the system display profile and displays over-saturated unwatchable video. On ALL modern mac computers!!!"
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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jun 04, 2020 3:12 am

If you take a look at my original post I mention that the images in QTX look considerably more dull on the P3 display when compared against the sRGB displays and Blackmagic ultra studio connected monitor. I want to know what color space and gamma to target when rendering out so that the image looks accurate in QTX on my P3 displays.
Last edited by AlexWalker47 on Thu Jun 04, 2020 3:38 am, edited 1 time in total.
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Dmitry Shijan

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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jun 04, 2020 3:38 am

- For SDR delivery you should just render your video to Rec709 and use Render tags Rec709.
- QTX player will transform in realtime your video color space to any Monitor color space so video will look the same on any monitor. (No desaturation and no oversaturation between sRGB and P3 displays)
- VLC player will passthrough (not transform) video from source to Monitor display, so it will look very oversaturated on P3 displays. And it will also always look slightly more contrast and saturated on sRGB displays than QTX player (because macOS color management gamma shift)
- I didn't test Blackmagic ultra studio. It may use it's own color hardware based management, or may don't use any color management at all, or may use macOS color management. It is a different broadcast-based system that may produce different look and may require different calibration.

My personal recommendation - keep things as simple as possible. Just use sRGB display for video monitoring.
More wide gamut displays, more different output cards and sources, more “Use Mac Display Color Profiles for Viewers” options you use - more problems between all that random mess.
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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jun 04, 2020 3:42 am

Thanks for all of that, but that's all precisely what I'm already doing. My Rec709 renders in QTX on a P3 monitor look nothing like my Rec709 renders in QTX on a sRGB monitor. In theory shouldn't the color management in QTX not allow this to happen? It should appear the same on an sRGB monitor as it does on the P3 monitor if both systems are color managed. Hence why I've been experimenting with rendering out with different gamut and gamma settings to see if I can match the look I've created on the rec709 reference display connected to my Mac Pro via Blackmagic Ultrastudio. My sRGB monitors match the reference monitor already.
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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jun 04, 2020 3:44 am

Yep, that's strange. it should look the same on sRGB and P3 monitors
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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jun 04, 2020 3:48 am

In your original post in this thread you mention the following:

"As a quick fix for P3 displays you can use monitoring correction LUTs made by Cosmin Hodiș-Mîndraș. More details in this post viewtopic.php?f=21&t=101253&start=50#p564992
Download LUTs here https://www.dropbox.com/s/0sux7nydfyk72 ... c.zip?dl=0"

I've attempted to use these LUTs on the timeline level to create a P3-ready version of the export to see if it would match in QTX, yet it seems to over correct and results in an image that's too dark. I suppose I could make a custom version for myself but I was hoping for a workflow that I could be confident is going to be consistent so I can just save the extra node as a power grade for future use.
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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jun 04, 2020 6:57 am

So what must people use for youtube/computer (non tv) players, in Resolve' project settings?
rec.709 scene, or rec.709 A?
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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jun 04, 2020 7:12 am

On macOS with P3 displays:
YRGB project with “Use Mac Display Color Profiles for Viewers” turned ON
Timeline to Rec.709 A
Final CST node to Rec.709/rec709 gamma
Set tags in Render Settings to rec.709/rec709

On macOS with sRGB displays you may use 2 options:
1. YRGB project with “Use Mac Display Color Profiles for Viewers” turned ON
Timeline to Rec.709 A
Final CST node to Rec.709/rec709 gamma
Set tags in Render Settings to rec.709/rec709

2. YRGB project with “Use Mac Display Color Profiles for Viewers” turned OFF
Timeline to Rec.709(Scene) (or whatever you want)
Final CST node to Rec.709/rec709 gamma
Set tags in Render Settings to rec.709/rec709

On Windows:
YRGB project:
Timeline to Rec.709(Scene) (or whatever you want)
Final CST node to Rec.709/rec709 gamma
Set tags in Render Settings to rec.709/rec709
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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jun 04, 2020 7:25 am

Dmitry, thank you, so much.
And will be understood that "rec.709" tag for ffmpeg/handbrake app?
You wrote, that app can't watch such tags.
I don't use proprietary h.264 encoders. They haven't a crf option for compress.

A little second question. You didn't happen to use 3dlut creator for color (https://3dlutcreator.com/) ? Just I don't know, where I can ask a moment about 3dlc' work with Resolve. The app is very good for color correction.. In my opinion, it better, than all fcpx/resolve/lumetri/etc tools, but it have problem - gamma shift, when I use it for video.
But, if you don't know about it nothing, so excuse me.
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Re: Final Explanation of Gamma and Color Shift Problems

PostFri Jun 12, 2020 3:45 pm

Great post.
I want to know if you are using a P3 color gamut display, such as LG Ultrafine 5K, will you choose the HD709-A icc in the Mac preferences?
When I set this up, I would not choose "Use Mac system color profile for the viewer."
The timeline color space uses REC.709 (Scene).
The output label will select "same as item".
So I got the same color on the viewer, QT, FCPX, VLC. But this color will look very saturated. And when I put the video on the iPhone, or when I watch it on the iPhone after uploading it to YouTube, it looks different.
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Re: Final Explanation of Gamma and Color Shift Problems

PostFri Jun 12, 2020 5:56 pm

aIf you are not truthfully progressive, maybe you shouldn't say anything
bTruthful side topics in-line with or related to, the discussion accepted
cOften people deceive themselves so much they do not understand, even when the truth is explained to them
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Re: Final Explanation of Gamma and Color Shift Problems

PostWed Jun 17, 2020 5:20 pm

Dmitry, you are a genius, I've been a silent lurker, observing all of this and trying to make sense of it all.

I have an Apple XDR display hooked up to my mac pro without a terranex 8k in between as of yet.

My current approach is to set the display reference mode in system preferences to REC709, and then in resolve leave the "Use Mac system color profile for the viewer" off, leave color management off or set to all REC709 Gamma 2.4 and at output, set both the color and gamma tag for my ProRes files to Rec709 2.4

It SEEMS that this yields pretty solid results that look the same in QTX as in Resolve as in After Effects or Premiere (but only if there I turn the color management off.) Also if I export a h264 using compressor from my flagged ProRes it looks the same.

If I leave the Tag off, I end up with a crunched QTX image.

If I switch the display back to P3 to emulate how someone on an imac would see it, it seems also to be ok, but it's hard to compare. If I send the video to my ipad pro, it looks very similiar to what I see on my Rec709 reference mode.

Am I doing everything right?

I did create a custom Rec709 profile in OSX with Powergamma of 2.2 and 120 nits, because my room is not ENTIRELY dark yet. Need to get better window blinds. A colorist friend of mine told me to do that to accomodate for my not ideal viewing environment and to proximate closer to the 2.2 gamma screens that most mac and iOS users will watch my content on and it seems to work well, but I don't trust this process fully :mrgreen: What do you think?
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Dmitry Shijan

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Re: Final Explanation of Gamma and Color Shift Problems

PostWed Jun 17, 2020 5:55 pm

I have no idea how those HDR XDR displays will work. HDR displays are made for HDR grading and for watching HDR content. Consider it as totally experimental option, or as parallel dimension that will never intersect with normal gamma displays.
Apple color management probably should transform SDR source to HDR under the hood. So if your display set to HDR P3 you can set YRGB project, "Use Mac system color profile for the viewer" ON, Rec.709 A gamma/color space Timeline, CST output node Log to Rec709.

It may work like this or may not work with XDR displays. Anyway it is very stupid to use extremely overpriced $6000 monitor that was not designed for Rec709 video to grade Rec709 video in Rec709 emulation mode :)
If you need to grade video to Rec709, just get for this work proper monitor that natively covers sRGB color space.
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Re: Final Explanation of Gamma and Color Shift Problems

PostWed Jun 17, 2020 6:17 pm

HDR display is capable of SDR for sure, so nothing special there. If you have display which behaves properly then it will simply switch to SDR mode. It's not like display have fixed output parameters- good ones can be calibrated and switch to different nits and gamut modes.
Apple display has SDR Rec.709 mode and it will be fairly accurate as for home display (most likely better than any Dell, etc.). It's not like it will be trying to convert SDR signal to HDR output.
If HDR display is good and can be calibrated then it's very typical that it's used for HDR as well as SDR grading.
What can be "stupid" is buying HDR display just to later grade SDR only (due to HDR displays high pricing of course).
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Re: Final Explanation of Gamma and Color Shift Problems

PostWed Jun 17, 2020 6:33 pm

Dmitry Shijan wrote:I have no idea how those HDR XDR displays will work. HDR displays are made for HDR grading and for watching HDR content. Consider it as totally experimental option, or as parallel dimension that will never intersect with normal gamma displays.
Apple color management probably should transform SDR source to HDR under the hood. So if your display set to HDR P3 you can set YRGB project, "Use Mac system color profile for the viewer" ON, Rec.709 A gamma/color space Timeline, CST output node Log to Rec709.

It may work like this or may not work with XDR displays. Anyway it is very stupid to use extremely overpriced $6000 monitor that was not designed for Rec709 video to grade Rec709 video in Rec709 emulation mode :)
If you need to grade video to Rec709, just get for this work proper monitor that natively covers sRGB color space.


I was playing with this "use mac system color profile for the viewer" and it seemed to produce results that were not looking clean, for example I saw some strange color bending that wasn't there in REC709 mode..
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Re: Final Explanation of Gamma and Color Shift Problems

PostSat Jun 27, 2020 8:17 am

And if I work in ACES colorspace, what must I do, that don't get a gamma shift one?
I like ACES, that in that one I can [more fine to change lightness and shadows] in Resolve, than in Davinci YRGB.

If I export video, when would be use ACES, to prores, that I won't have problems, but! if, I after it, convert a such prores stream to h264, that I will have a gamma shift problem.
Perhaps Resolve add a some tag in prores.mov and that tag can't understand with third-party encoders, like as x264 etc.
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Re: Final Explanation of Gamma and Color Shift Problems

PostSat Jun 27, 2020 8:26 am

There is ACES Transform node that allow transform to/from ACES inside YRGB project. ACES workflow just consists of input presets + ACES AP0 color space with linear gamma + output preset. There are also ACEScc and ACEScct with Log based gammas. And also smaller sized ACES AP1 color space.
YRGB is the only universal project setting real you need.
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Re: Final Explanation of Gamma and Color Shift Problems

PostSat Jun 27, 2020 8:51 am

Dmitry Shijan wrote:There is ACES Transform node that allow transform to/from ACES inside YRGB project. ACES workflow just consists of input presets + ACES AP0 color space with linear gamma + output preset. There are also ACEScc and ACEScct with Log based gammas. And also smaller sized ACES AP1 color space.
YRGB is the only universal project setting real you need.


That's great, but excuse me - I'm freezing)). I'm creating a new project and change output gamma as rec.709-A. Don't change a color science. Be stay it as YRGB. After it I add an ACES transform node {and}? Excuse me, again.
If I just would be ACES transform node before all my nodes and after, that I get nothing. When I change shadows down, that I'll see as waveforms get the safe colors and the end.
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Re: Final Explanation of Gamma and Color Shift Problems

PostSat Jun 27, 2020 9:02 am

Perhaps, I must to add my clips to group.
In group pre clip I add aces transform as input=aces and output=rec.709. And in post clip I do an inverse one - input=709 and output=aces.

It should be?
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Dmitry Shijan

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Re: Final Explanation of Gamma and Color Shift Problems

PostSat Jun 27, 2020 9:17 am

YRGB project.
Timeline: rec.709-A
“Use Mac Display Color Profiles for Viewers” ON

RAW BMDFilm -> ACES Transform Node (BMDFilm to ACES) -> adjustments nodes -> ACES Transform Node (ACES to Rec709)

or:

RAW BMDFilm -> ACES Transform Node (BMDFilm to ACES) -> adjustments nodes -> CST Node (ACES/Linear to Rec709)

You can insert in between transforms to to ACEScct or ACEScc if you prefer to color correct in Log.
You can mix ACES Transform Node and Resolve CST Node inputs/outputs. They do the same but use slightly different transform math and produce slightly different "look". It is hard to imagine more flexible and universal workflow.
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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jul 02, 2020 4:25 am

There's one exception. When I work with adjustments nodes and want use a qualifier, that qualifier show a very strange picture. if I highlighting regions, that I select - all image is like in some screen blending mode. Even if I just to enable highlighting for imgge. Without a some selecting.
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Dmitry Shijan

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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jul 02, 2020 4:45 am

It could be due Linear gamma. Some things don't works as expected in Linear gamma.
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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jul 02, 2020 4:49 am

For what, It's work without a such "screen" effect in aces color science ;)
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Dmitry Shijan

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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jul 02, 2020 5:06 am

As you may see ACES project settings in Resolve are ACEScc and ACEScct. Both are Log gammas, but not a Linear.
Can you explain why exact you want to use ACES? ACES will not make your workflow easier. Before start to work in ACES, learn ACES specification. ACES is very abstract definition. ACES consists of few totally different color spaces and gammas. And they keep add new options and make things more and more confusing. Also D60 white point produce slight color temperature shift compare to common D65 white point used in most modern color spaces. No fine control over Luma and Saturation mapping when you transform to Rec709. It just produce basic ugly look. These are the main reasons why i avoid ACES workflow.
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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jul 02, 2020 5:18 am

dariusii wrote:..that in that one I can [more fine to change lightness and shadows] in Resolve, than in Davinci YRGB.


viewtopic.php?f=21&t=101253&p=643490#p642028

There is a movie by Pavel Kosenko on YouTube about that moment, if you know Russian.

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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jul 02, 2020 5:53 am

He just explains fundamental difference and advantages of working in Log gamma and Wide color space vs sRGB/Rec709/Gamma2.2. Same things described in my workflow example, but instead of ACEScct i use RED WideGamut color space with REDLog3G10 gamma: viewtopic.php?f=21&t=65149&p=543725#p537852
ACES is just a few color spaces, gammas and in-out camera profiles and transformation math between them developed by some dudes in Hollywood.
Resolve YRGB with CST nodes can do exact the same things, but in way flexible and compatible way. There is also more simplified YRGB color managed option.

ACES color space is based on "nothing", it is just huge volume but same time it still clips in some specific areas that normally captured by most modern digital sensors.
RED WideGamut color space fits better to average native digital sensor color space and don't produce clipping.
ACEScct is Log curve based on "nothing". As a result it have some rather artificial response when you adjust contrast.
REDLog3G10 Log curve based (formally stolen and improved ;) ) on Cineon Log curve made by Kodak in 90's based on real film stock contrast response. It produce nice looking response when you adjust contrast.

ACES AP0 vs BMD Wide Gamut Gen 4 (Red channel clipping)
Image

RED WideGamut vs BMD Wide Gamut Gen 4 (Red channel is not clipped)
Image
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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jul 02, 2020 10:40 am

That's nice, but I can't so change lightness, if I will use cst with red one. (redwidegamutrgb/redlog 3g10 > adjustment > invert to rec.710). waveforms still across upper and lower borders, as if I just use rec.709 without any cst ones. When I will use lift or gamma tools in Resolve.

He was certainly to compare log paradigm with srgb/rec.709, but in his example the source had been as a simple rec.709 one. And he had present a very interesting moment with a luma manipulation. A qualifier didn't show a strange highlight. Just there's a one exception - he don't see a need to explain, how that "piece of work" to export to prores422.mov. - If I'll be export it to prores422.mov, that I don't see any problems. But if I will to encode such prores422.mov to h.264 with any opensource encoder, that I'd will catch a gamma shift. Perhaps in that mov file is a some gamma tag after resolve.
And resolve's h.264 encoder is a simple proprietary encoder. without any opensource features.

You are right. But I can't understand, what I must to do, that use his idea and your adjustment to real world/life. In my chance a cst nodes don't give that effect, that he had present with rec.709 source. He used rec.709 film as src in that example.
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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jul 02, 2020 11:02 am

If something goes wrong, it means you do something wrong or apply wrong color and gamma transforms. I have no idea what exact project settings you use and what exact color and gamma transforms you apply in different places. Discussion about ACES is far offtopic and don't related to gamma shifts problem at all. I can suggest to start new topic about ACEScc/cct vs other Log gamma curves response and provide project color settings, raw settings, clip and timeline nodes settings you use to understand what is going on. Also provide side by side tests to see the difference.

P.S. it is nice to see that Dehancer development now continued as a OFX plug-in. Seems like decent all-in-one tool for film emulation with a lot of interesting info background in blog posts. But same time it feels slightly overpriced and late because similar G'MIC and RawTherapee film emulation LUTs made with same process exists long time ago and formally free viewtopic.php?f=21&t=77553&p=637455#p569634 and film emulsion halation workflow in Resolve was discussed in details at LGG forums.
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Re: Final Explanation of Gamma and Color Shift Problems

PostThu Jul 02, 2020 12:14 pm

A fork of that one: viewtopic.php?f=21&t=116995
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Re: Final Explanation of Gamma and Color Shift Problems

PostFri Jul 03, 2020 7:46 am

Any thoughts about Dmitry's method but not using the transform?
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Re: Final Explanation of Gamma and Color Shift Problems

PostFri Jul 24, 2020 6:05 pm

My head is spinning -

I am grading footage from different cameras, on a probe calibrated (saved to ICC profile) GUI monitor, and output via decklink to a professional reference monitor.

All I want is YouTube to match my pro reference monitor, which is set to Rec709 2.4.

What settings do I use? IDGAF about GUI or MacOS.
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Re: Final Explanation of Gamma and Color Shift Problems

PostFri Jul 24, 2020 6:12 pm

And, is there any way to re-tag a video, encoded in ProRes 422 HQ, Which is showing as 1-1-1, Rec709/Rec709 to whatever tags will be correct for youtube? When I look on the app "Screen" it looks correct, when I use "QuickTime" it looks like ballsack.
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Re: Final Explanation of Gamma and Color Shift Problems

PostSat Jul 25, 2020 10:21 am

Gian Salucci wrote:All I want is YouTube to match my pro reference monitor, which is set to Rec709 2.4.
This is the workflow that I follow for web trailers and commercials:

Grade your project as normal for your reference display. Ignore what it looks like in the GUI.
Before export add a CST OFX to timeline node set to transform from 2.4 gamma to 2.2 gamma. In the deliver page make sure the color space and gamma tags are both set to REC709. Your exported file will match (as close as possible) in software apps and YouTube/Vimeo on standard computer displays, iPhones, iPads, etc. to what you saw on your reference monitor.
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Re: Final Explanation of Gamma and Color Shift Problems

PostSat Jul 25, 2020 7:37 pm

For MACs you need to convert to new Rec.709-A preset, not 2.2 gamma (for PCs sRGB or 2.2 is better choice).
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Re: Final Explanation of Gamma and Color Shift Problems

PostSun Jul 26, 2020 2:19 am

Andrew Kolakowski wrote:For MACs you need to convert to new Rec.709-A preset, not 2.2 gamma (for PCs sRGB or 2.2 is better choice).
REC709-A only matters if you're trying to color manage the GUI on the new P3 Macs, which I'm not because I have a calibrated external reference monitor. I don't care one bit what the GUI looks like, so I don't need to use the REC709-A option at all.
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Re: Final Explanation of Gamma and Color Shift Problems

PostSun Jul 26, 2020 7:34 pm

Rec.709-A is not just for screens with P3 gamut at all. It has not much to do with screens itself (it works for any Mac screen).
Rec.709-A is math which Apple uses behind Rec.709 (1-1-1) tag in their color engine. Whatever is tagged 1-1-1 will use reverse math based on Rec.709-A and this is the key point here.
If you have video which is graded on reference monitor and want it to look "the same" on Macs you convert it to Rec.709-A and you should have good match during preview on Macs (with any preview managed by Apple color engine).

If you convert your "perfect video" with 2.2 gamma it may work fine but only on non-color managed preview (which is not what Apple is by the default- Safari, QT etc). It will also never look well on P3 gamut screens.
Question was specifically for youtube playback. 2.4 (or 2.2) graded video on reference monitor won't look "the same" in Safari as on reference monitor. If you convert it to Rec.709-A then it should be fairly close (depending how well is your Mac screen profiled).
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Re: Final Explanation of Gamma and Color Shift Problems

PostFri Jul 31, 2020 1:59 pm

Andrew Kolakowski wrote:If you have video which is graded on reference monitor and want it to look "the same" on Macs you convert it to Rec.709-A and you should have good match during preview on Macs (with any preview managed by Apple color engine).


But then it'll look wrong on your reference display, and on non-Mac devices. Right?
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Re: Final Explanation of Gamma and Color Shift Problems

PostFri Jul 31, 2020 2:34 pm

Can we agree, we shouldn't bother supporting the unsupportable by Apple. Let them fry, it's up to them to fix things up.
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Re: Final Explanation of Gamma and Color Shift Problems

PostSat Aug 01, 2020 10:05 pm

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Re: Final Explanation of Gamma and Color Shift Problems

PostSun Aug 02, 2020 9:26 pm

Good one. It really shows how messy is whole industry with its standards and its "interpretations".
Another one- Baselight move was to hide (leave only for legacy purpose) 1.96/5 (BM calls is Rec.709-A) based preset when BM just added is as a valid choice in Resolve- this is exactly what we need :lol:
All one big mess!
Last edited by Andrew Kolakowski on Sun Aug 02, 2020 9:32 pm, edited 2 times in total.
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Re: Final Explanation of Gamma and Color Shift Problems

PostSun Aug 02, 2020 9:30 pm

videosoul wrote:
Andrew Kolakowski wrote:If you have video which is graded on reference monitor and want it to look "the same" on Macs you convert it to Rec.709-A and you should have good match during preview on Macs (with any preview managed by Apple color engine).


But then it'll look wrong on your reference display, and on non-Mac devices. Right?


If you are talking about this converted to Rec.709-A then yes, it will be wrong with mentioned cases.
It's all one big mess.
Apple needs to sort out their color management to include proper preset for 2.4 gamma (and also add support for files tagged as 2.2). Then we could at least have some alignment with PC and Mac. Windows needs to add proper color management, so we can have correct preview for different gamuts (and gammas). You can't anymore treat every video on PC as around 2.2 gamma based with Rec.709 gamut. It's just not going to work anymore.
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Re: Final Explanation of Gamma and Color Shift Problems

PostFri Aug 07, 2020 3:47 pm

This thread has been super helpful. I'm using Rec.709-A with "Use Mac Display Color Profiles for Viewers" and it's helping me tremendously. I'm finding that there will be two workflows, one for web-destined content and one for broadcast...which is super frustrating. lol
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Re: Final Explanation of Gamma and Color Shift Problems

PostFri Aug 07, 2020 4:01 pm

bigflavorfilms wrote:This thread has been super helpful. I'm using Rec.709-A with "Use Mac Display Color Profiles for Viewers" and it's helping me tremendously. I'm finding that there will be two workflows, one for web-destined content and one for broadcast...which is super frustrating. lol


In a way, that's always been the case: when a movie is graded, for example, there will be separate versions for the cinema, and for TV, and maybe the DVD/Blu-ray versions will be different too. This is "easy": because there are standards (albeit a few different versions), and for the most part those standards are stuck to by cinemas, broadcasters, and the default settings of TVs (most of the time).

The problem here is that versions destined for web is a mess: as there is no unified standard here: Windows, Mac, and mobile devices all will look different; Rec709-A might work for some, but not all; different devices use different gammas; even within one device there will be differences (like on a Mac, depending on if a program is colour managed or not (like how Safari can look different to, say, Firefox); some displays will be DCI-P3, some will be sRGB; different codecs will look different depending on how the playback software reads them (and any flags they may carry)... etc etc.
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Re: Final Explanation of Gamma and Color Shift Problems

PostFri Aug 07, 2020 4:57 pm

videosoul wrote:
bigflavorfilms wrote:This thread has been super helpful. I'm using Rec.709-A with "Use Mac Display Color Profiles for Viewers" and it's helping me tremendously. I'm finding that there will be two workflows, one for web-destined content and one for broadcast...which is super frustrating. lol


In a way, that's always been the case: when a movie is graded, for example, there will be separate versions for the cinema, and for TV, and maybe the DVD/Blu-ray versions will be different too. This is "easy": because there are standards (albeit a few different versions), and for the most part those standards are stuck to by cinemas, broadcasters, and the default settings of TVs (most of the time).

The problem here is that versions destined for web is a mess: as there is no unified standard here: Windows, Mac, and mobile devices all will look different; Rec709-A might work for some, but not all; different devices use different gammas; even within one device there will be differences (like on a Mac, depending on if a program is colour managed or not (like how Safari can look different to, say, Firefox); some displays will be DCI-P3, some will be sRGB; different codecs will look different depending on how the playback software reads them (and any flags they may carry)... etc etc.


Absolutely. Web IS a mess. All we can do is shoot for even middle ground somehow. I don't think we will ever have unification around device/screen colors and gamma. Manufacturers each think they have the best approach.
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Re: Final Explanation of Gamma and Color Shift Problems

PostFri Aug 07, 2020 6:38 pm

Jamie LeJeune wrote: This is the workflow that I follow for web trailers and commercials:
Grade your project as normal for your reference display. Ignore what it looks like in the GUI.
Before export add a CST OFX to timeline node set to transform from 2.4 gamma to 2.2 gamma. In the deliver page make sure the color space and gamma tags are both set to REC709. Your exported file will match (as close as possible) in software apps and YouTube/Vimeo on standard computer displays, iPhones, iPads, etc. to what you saw on your reference monitor.


Couldn't you just change your reference monitor to gamma 2.2? Since everything I do is for the web I set my reference monitor to Rec709 gamma 2.2 and have my timeline color space and output color space set to Rec709 gamma 2.2 as well (I use Resolve Color Management). Rendered files uploaded to Vimeo seem to match well enough when I look at them online on multiple computer displays and iPad.
Resolve 16.1.2 Studio, Mac Pro 3.0 GHz 8-core, 32 gigs RAM, dual AMD D700 GPU.
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Re: Final Explanation of Gamma and Color Shift Problems

PostFri Aug 07, 2020 10:48 pm

But even DCI is a lower standard since rec2000 and 2100, and we are talking of going lower again...it just doesn't sound good enough.

Cinema seems to have a problem playing with others. Cinema has to be 2k just a little wider format than 16:9 fullhd. The issue is ensuring standards support and as I wrote before, about standards algorithms and code (high efficiency, speed, energy and size) being supplied to developers to keep all systems in performance sync, probably no solved, except for those who refuses to use the code or algorithms at least, who can wear their own non compliance. Selling a big compliance code or algorithm tick, would ensure customers which one to buy, and motivate code and algorithm adoption. We actually don't want industry standards body to control use of standards, we still want users to control their own playback levels rather than some suable megalomaniac industry trying to enslave people's eyeballs to their often errant vision of how things should look, because some director likes a certain flavour of wannabe drab. Use of code only in the performance section as just one element in the rendering path, ensures users can adjust or shift the look towards their regular taste, partway to full way, and for players to do player unique feature picture processing and objective looks. This may mean the code is broken up into segments that are used in the code chain, to allow developers to customise their products.


The need for rec2020 HDR standard support:

I actually get my set to push the content into the rec2100 space, and brightness, rather stimulating colourful version of reality in a new light. My set can handle it without wrecking faces and the scene, it's like another startling world, been using it on the current lost in space series. A shame HDR content doesn't have enough bits to hold it together when pushing it a lot. It is a legitimate grading choice, and a Lost in Space movie in rec2020 graded like the look I get here, would be visually stunning. But here's we are saying we need to turn it down to 709. Rec2020 has spectacular edge to it, P3 has a little edge to it, 709 less again. Corporate is invested heavily in studio and theatre chains, if they want to get people in seats in theatre, they need to do this. Msny action movies would benefit from this, others could stick to a more conservative matrix like grade. People ask when will people get dick of action super hero movies, but people haven't got sick of other genres like romance, comedy, drama, in thousands of years. So, it is important to look at doing this as it's about emotional response to the movie and picture, and action is likely to be around.


A new standard:
What we need is developers like Apple, to offer standard options, and for their to be one standard over all formats, which can adapt in a custom way to format, usage environment and device, with detection of those, to maintain a more consistent picture and audio experience relative to user preferences. Such a standard should cover the complete human spectrum and beyond, for scientific and industrial usage (a second scientific mode which can be defined sometime in the future afterwards) but also handy for certain sensor and grading developments. (I'm looking at how to design a sensor with many times more bands of primaries to map colour more accurately, this might be hundreds of bands). We already know enough to do a sort of finale stabdard right, with the scientific version of customisable number of primaries, spacing, curve responses, processing etc, with a future preset to handle content usage past the main content version proposed here, taking into account any future discoveries concerning content. Such future industry standard preset relieving the need to define the usage via the scientific feedings custom setup each time. You can see where I am going with the content version of this, it can be a subset of ACES which already exists and is already supported out there. ACESconsumer..

Even if we need to dump faux 10 bit HDR and go to 12-16 bits to give enough extra bits to allow users to customise their own looks. Trying to move HDR image around on a TV is prone to issues, as the the levels go out of alignment. We also need to go to a extra round of super premium quality TV sales, where these features could be used in encrypted streaming function to protect super premium content pricing.

Lobbying:

Wherever BM like it or not, when they bought Resolve, they bought into the industry process and it's responsibility. Somebody else can define things, maybe in a fashion they don't like, unless they are involved. Lobbying standard bodies to lobby developers like Apple to fix issues is what the industry and people can do. They can lobby Apple directly. If the interface in the team is dismissive, go to the teamm. If the isolated team is dismissive, go over their head. It's a genuine issue, so you should eventually get to somebody who will listen. I doubt one day that Tim Cook needs to wake to see an email about it. In a good company, it shouldn't need to work like that.
Last edited by Wayne Steven on Fri Aug 07, 2020 11:12 pm, edited 3 times in total.
aIf you are not truthfully progressive, maybe you shouldn't say anything
bTruthful side topics in-line with or related to, the discussion accepted
cOften people deceive themselves so much they do not understand, even when the truth is explained to them
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