QT Gamma Compensation LUT

[NickiDoane]

Hi There, 

Months ago I found a download here I think for the QT Gamma Compensation LUT ... I just updated my mac and now the file is a .cube and I don't know how to change it to a usable file again. Help? Does anyone know where I can find the file again to download & use?

[NickiDoane]

Nevermind having a moment - it's fine.

[chrisw44157881 · Accepted solution]

i am not aware that the lut doesn't work with mac. premiere reads the file so it should still work.

download lut here:

https://community.adobe.com/t5/premiere-pro-discussions/quot-why-does-my-footage-look-darker-in-prem...

just place it in location here:

https://community.adobe.com/t5/premiere-pro-discussions/faq-premiere-pro-lumetri-color-custom-lut-di...

and render out with lut.

[zensei24321378vihf]

Is this still a thing that needs to be done in July 2022 with latest Adobe?

[R Neil Haugen]

That of course, depends.

As the need ... or use of that LUT ... is caused by the Mac OS color management utility ColorSync applying a non-standard gamma to Rec.709 video files.ColorSync, for some reason, uses a 1.96 gamma.

So Rec.709/SDR video files are displayed with lighter shadows and mids on a Mac, than they would be if displayed with the "normal" Rec.709 gamma of 2.4.

Premiere always attempts to operate by the Rec.709 standards, including it's internal monitors which are not 'controlled' by ColorSync. So the image typically is darker within Premiere than outside on the same Mac computer.

That LUT will essentially push the midtones and shadows a bit darker in the exported file, so that when viewed on a Mac, outside of Premiere, the file will look more like it did while viewed in Premiere.

But of course, then outside of the Mac-sphere, on a non-Mac system, that file will now be a lot darker than it appeared on the Mac within Premiere. Because on non-Mac gear, the Rec.709 video file will probably be displayed with a correct 2.4 gamma.

So ... the choice is between two imperfect things:

• A bit light on a Mac, but "normal" outside of Mac displays without the LUT.
• "Normal" viewed outside Premiere on a Mac, but too dark outside of the Macs.

That dilemma can't be "solved" by a version change with an outside app like Premiere or Resolve. The need/use of the LUT could only be changed by a change of the standard used by ColorSync.

Neil

[Aadnan26492056qqa9]

Could have made it easier for everyone uploading to youtube. Could have been a toggle and not a random file that's not even provided by premiere from the get go.

[R Neil Haugen]

True.That would have been a lot easier for the users.

Although ... when you apply that to a file, you do understand it's going to look a lot worse ... very dark/contrasty and over-saturated ... on all non-Mac screens, right? For example, if you have any scenes that are relatively dark to begin with, the shadows will simply crush.

Which is why my colorist buds ... mostly Mac people of course ... are furious with Apple over creating this problem.

Neil

[defaultqjtdlqoon3z5]

Dear Neil, 

We understand that you have strong convictions about the way you believe color space should be accomplished. However, we must consider the bigger picture and the fact that a much larger group is already working towards completing and editing videos in a certain way specifically for Apple products. It is important for us to work together and come to a compromise rather than insisting on doing things solely our own way.

While we respect your beliefs and opinions, it is a little bit selfish to insist on doing things only your way when there are so many other people involved in editing. By coming together and finding a solution that works for everyone, we can ensure that the task is completed efficiently and effectively.

From the thousands if not tens of thousands of people who edit video for devices, we urge you at adobe to consider the benefits of working together and compromising in order to accomplish meaningful this important task. We are the paying customer. Let's put aside our individual desires and focus on the greater good to fix this adobe color space issue so that exports look like the edits... It is time. It has been years.

[defaultqjtdlqoon3z5]

For anyone finding this forum. The fix listed above with the Gamma Correction Lut still does not accomplish the desired result of maintaining your color grading. If adobe can render a preview that is vivid it should be able to create an export that is vivid as well. 

[R Neil Haugen]

What a bizarre response ... let's review the situation.

The "normal" standard for Rec.709 is to apply the camera and display transforms. That is the regular & expected method in all pro broadcast applications.

Adobe applies that universal standard to the media.

Apple chooses to work differently, and does NOT apply the display transform. Which is why the same file looks different outside of full Rec.709 color on a Mac ... or anywhere else.

That isn't opinion, it's just the practical "what is".

Now, how is Adobe supposed to solve that? I'm quite serious here.

What do you want Adobe's video people to do about this, being as they have no control of what Apple chooses to do whatever.

So again ... how is Adobe supposed to fix a choice by Apple?

Neil

[R Neil Haugen]

To "default"s second post ... that same video will have full saturation and shadow depth if viewed on a full-on Rec.709 setup.

It is only when viewed with an incorrect display gamma on a Mac that it will seem to be lighter in shadows and low-saturated. As if you send that file to me or anyone with a full Rec.709 viewing system, it will look as it does within Premiere on your Mac.

Neil

[dorisisabel]

Is it possible, that the Link/Download doesnt work anymore? 😞

[Tom28342070zxad]

I downloaded the LUT (which appears to be a load of text, but it works) from the link below then set export to h.264 (high-resolution 1920x1080) went to effects in the export window, selected the LUT from where I had saved it, and it worked perfectly.  Thank you for the advice!!!

[JJRiley]

Hi - how did you get Media Encoder to recognize the LUT? I placed the cube files in a location and selected them, but it says there is a low level exception (see screen shot). I tried saving the cube file on my desktop as well as our video server, but it won't apply. I used the vimeo preset first and then tried the match source high bitrate preset, but it still shows as none. Thanks for the help.

[R Neil Haugen]

They have a bug where that line says "none" even though the LUT is applied ... so if you complete the export, is it applied?

And of course ... if that LUT does get applied, understand the file will be very dark when viewed on a non-Mac display. Due to the underlying nature of the problem.

Neil

[JJRiley]

Thanks Neil - so I just did what you said and it said "applied" the encode looks good on the mac. I didn't realize that it would be very dark if viewed on a non-mac. So for review and approval the mac users will like what they see, but the PC users will see a darker encode?

[R Neil Haugen]

Yes.

Because the problem is specifically caused by Apple's choice to use the camera tranform function ... essentially gamma 1.96 ... as the only tranform, skipping the also required gamma 2.4 display function added in Bt.1886.

The "original"  Rec.709 was created while 'we' were still all using CRT monitors. Which had a specific native curve to the shadows of the signal.

As digital "flat panel" monitors came into existence, Bt.1886 was addended to Rec.709 to compensate for the flat response of the digital panels. So that 'we' still got essentially the same image.

That was back in the area around ... 2008 or so? Something like that. And all broadcast specs require the 'full' Rec.709 ... sRGB primaries, D65 white point, gamma 2.4 display transform, around 100IRE/nits total brightness.

So my Rec.709 compliant system will display that file as you see it within Premiere, pretty close. As will any fully Rec.709 system.

It's only lighter when viewed on a Mac, with apps that allow the Mac ColorSync utility to handle color management. Such as QuickTime Player, and Chrome & Safari browsers.

VLC player and Firefox normally do not allow ColorSync control, so they can be easier to use to check non-Mac 'views' of a file.

Neil

[JJRiley]

Got it. Thanks again for the explanation Neil.

[R Neil Haugen]

Sure.

I work for/with/teach pro colorists, mostly Mac geeks of course, who are really ticked about this. If they can't "solve" this, you & me certainly can't. It's one of those odd decision things, sadly.

Neil