Color correcting source clips: playback and export show different color grading

Ok ... I work for/with/teach pro colorists, have for about a decade now. Including the team that made the full training videos for DolbyLabs on pro colorists use of DolbyVision HDR in Premiere Pro. Started with Pr back in CS6 and the first CC series, while we had the full grading app SpeedGrade in the Adobe suite.

Color is something that can at times with certain things be handled simply, and at others, it's a rabbit hole of infinite depth. Literally.

The Basics

First, no capture device ever actually sees color. They only record variances of brightness. And use a mix of a color screen over the sensor in a pattern and a ton of mathematical calculations in the camera processor to manufacture "color" data. And as no two sensors can be manufactured to be totally identical, no two "identical" cameras will even produce identical images side by side. No two screens can be set to be identical either.

And that last doesn't even touch the differences between the hardware and software used to feed images to screens, and of course the viewing environment during watching.  Use the same tablet on a park bench at noon, and a dark bedroom at night, the same image will actually be quite different.

Thanks to Apple!

Your Macbook is defective by design by Apple ... as the ColorSync color management utility in the OS is set to use a display transform of essentially gamma 1.96 for Rec.709 video files. The long-held, long-published standard for screens displaying Rec.709 video is essentially gamma 2.4.

Note, Mac desktops with Reference modes, when set to HDTV, will use the full Rec.709 specs. So only on Macs without Reference modes, will Rec.709 imagery be displayed at gamma 1.96.

What screens and/or apps use ... what?

Mac screens without Reference modes use gamma 1.96 but only  with apps that allow ColorSync to control display. Such as QuickTime Player, Chrome and Safari browsers.

But note! On those same Macs, VLC and Potplayer along with the Firefox browser tend to ignore ColorSync, and use the correct 2.4 display gamma.

ALL other systems will normally use gamma 2.4 for Rec.709 media, whether monitors, TVs, or 'devices'. Gamma 2.2 is actually the 'web' thing for sRGB still images, not video. There are a few monitors and TVs that do use gamma 2.2, but it's close enough to a gamma 2.4 image to be not a problem.

What Premiere Color Management Settings should normally be always used?

Display Color Management, auto detect log, and auto tonemapping should be on for most users.

 What Viewer Gamma should I use and why?

That all depends on several decisions on your part. 

Do you worry most about on your computer or on those with 'normal' Rec.709 display?

If you only care about how it looks on your display, and other Macs without Reference modes, set your Viewer Gamma option to gamma 1.96/QuickTime.

Result? Outside of Premiere in QuickTime Player the image will be similar to within Premiere ... if as above, you view in Qt player, Chrome, or Safari. On all other systems, it will be much darker. Maybe oversaturated also.

What is your viewing environment while doing your color and tonal corrections process?

If you have a normally lit room, and are going for general viewing across systems ... use the gamma 2.2 viewing option, as specified for professional grading in a bright-light environment.

Only grade with the Viewing gamma 2.4 option when grading in a darkened room!

That is the professional "standard" for grading, always done in a pretty dark room (not pitch black but close) with a neutral gray surround visually. To the specs. 

Can we get something that looks the same on both Macs without Reference and everything else?

No. This is not physically possible.

Pro colorists have tried everything under the sun, including messing with NCLC tags and such, but nothing actually gets all systems using the same display gamma.

How close are most screens to each other anyway?

Oh Holy Moly, not even "close" ... not even. Seriously.

It's been demonstrated, many times, that two "identical" monitors, calibrated with the same system and hardware, fed identical signals from one computer, will not show fully identical images.

Now take different screen manufacturing processes, hardware feeding the image to the screen, OS for the device, manufacturer's constant image manipulations (on all devices!) to "enhance the viewing experience" ... different viewing environment for brightness and color surround/reflections, let alone viewers messing with color settings ... and the image shown won't be even at all close.

But no one will ever know they aren't seeing 'the original image' ... because they see everything "through" the same mess of crud on that screen, whatever it is.

What is the purpose of grading then? If you can't control what people see?

You grade according to The Standards, so that the media you produce, when seen on any other screen, will, in relative terms! ... look like other professionally produced media on that screen.

As it will never look like you saw it when grading.

First, that's a small enough difference that it simply won't be anything anyone will ever notice. Something colorists are taught right at the beginning, no one will ever see the same image you saw, no matter the method of delivery.

Next, you didn't give any of the necessary information ... what is your color management down the entire Lumetri panel Settings tab ... the one named Settings  ... set to?

Display color management, auto detect log, auto tonemapping, sequence working space, viewer gamma, and whether you're on a Mac without Reference modes or a PC, all matter here.