Gamma shift in Color? the solution...

[Evangelos Achillopoulos]

There are some problems with Color and FCP regarding gamma shift.

The problem seems not to be consistent to all users... it seems not to be related to the Black magic card... in general when you use a broadcast monitor and a Video card it shouldn't have shift... but if you use your computer monitor as a display, it may have that problem... In any case this is a solution... The problem seems to be on the Video monitor when using Kona 3.

Attached is a LUT that normally is provided with the Color software package, but its reported by some users that its not available on the LUT's folder of Color...

The place to be is [Your system disk]/users/[your_username]/library/application support/color/LUTs

Before start grading with Color, go to File > Clear display LUT, do your work and then before render, go to File > Import > Display LUT load the FCP.mga, and then render with the LUT. when Color ask to render with LUT say YES.

This LUT is correcting the gamma shift and allows you to get on the rendered files what you ware seeing in Color on FCP...

The slight difference in white level it is, probably, because FCP is legalizing the output to broadcast safe... so no super whites... unless you select allow super white in FCP in the sequence settings or enable broadcast safe in Color...

The LUT is useful when you grade on the computer monitor and NOT on a broadcast output (SDI or HDSDI) with a Blackmagic or an MXO...

In this case the LUT its not needed. An exception to this case is the AJA Kona 3 that needs the LUT.

Thats my contribution as a color management specialist...

So here it is...

 

[Cüneyt Kaya]

as always, thank you evangelos.

 

[Marcus Struzina]

Likewise , thanks Evangelos , searched but no luck, I was contemplating a clean instal, so thanks.

 

[Kwan Khan]

Thanks Evan

 

[Laurent AZEMA]

Thanks Evangelos

I just tryed the FCP LUT as you said.
Generaly my result in FCP is darker than the color grade. But If I apply your workflow, the result is far darker in FCP. Isn't logical to apply the lut before rendering???

 

[Evangelos Achillopoulos]

Thanks Evangelos

I just tryed the FCP LUT as you said.
Generaly my result in FCP is darker than the color grade. But If I apply your workflow, the result is far darker in FCP. Isn't logical to apply the lut before rendering???

Yep...

If this is the case then I have write it vice versa...

Grade with no LUT and just render with the LUT...

Do the test and post it in order to correct the original post...

I'm film recording some tests so I will be around for the next couple hours...

 

[Laurent AZEMA]

I just finished a quick test.
Rendering with the LUT, the result is close to a match but the high light seems a lit bit brighter in color. That's said,right now I'm runing the test at home whitout any calibrate monitor, so this is not the best place to judge a lut

By the way, have you worked with Athens Central film production?

 

[Evangelos Achillopoulos]

The slight difference in white level it is, probably, because FCP is legalizing the output to broadcast safe... so no super whites... unless you select allow super white in FCP in the sequence settings or enable broadcast safe in Color...

No I haven't worked with Central... sorry with everyone else yes...

I have corrected the original post... sorry guys...

 

[Kaku Ito]

I think we must mention that gamma from Color changes according to the output format, too.

In my case I established a workflow using Blackmagicdesign's Multibridge pro.

In Color, select 1080/23.976 RGB in the video output, do not apply any LUT, don't trust the desktop output but the video from the Multibridge Pro, then export as DPX.

If you want to bring in the DPX to FCP, at this time I'm conforming manually (dough!, hope bob from Glue Tools comes out with this support soon), then set the Glue Tools import setting with "Linear (adjustable W & B Points) at 980 for the White Point and 0 for the Black Point. Then I get pretty close output from the Multibridge Pro on the monitor in the FCP as how it was from the Color.

With beautiful Glue Tools you can read the DPX in FCP straight and if your RAID is fast enough then it'll pretty much play back in real time.

Also, I confirmed that you can convert from DPX to Blackmagicdesign's 10-bit RGB (4:4:4) on FCP, things won't shift so much.

On the other hand, there must be a reason why AJA software codec shifts gamma so much (this is when you don't have the hardware installed, so I don't know if this is true when installed), but I couldn't come up with good way to export as AJA 10-bit 4:4:4 then to convert to something else with good balance.

 

[Brian Langeman]

Has FCP been updated on this issue? I remember using this LUT to output Prores HQ from Color to Final Cut and it working for me. But the other day when doing this it ended up looking lighter. I rendered again without the LUT and the final movie ended up looking the same as the grade in Color. This is when rendering to ProRes HQ.

Also, does anyone know why the levels change in Final Cut when you're playing footage as opposed to scrubbing it or when it's stopped?

 

[Charles Angus]

Using the LUT as you describe, what gamma should the computer monitor be calibrated to for work in Color? Is this LUT so you can grade on a gamma 1.8 monitor?

 

[Brian Langeman]

All this LUT is for is to fix a gamma shift that FCP was doing to Color graded files.

 

[Evangelos Achillopoulos]

The LUT is useful when you grade on the computer monitor and NOT on a broadcast output (SDI or HDSDI) with a an AJA or a Blackmagic or an MXO...

In this case the LUT its not needed.

The original post is updated.

 

[Kaku Ito]

Blackmagicdesign and MXO output 1.8 (or no gamma applied) from Color when RGB material on the timeline.

So, you'd want the Blackmagic LUT to be set with x 1.2222 in the gamma section for the monitoring, but when Color outputs DPX files, Color makes the change to write the files with 1.2222.. gamma shift.

In case of MXO and MXO2, you'd have to apply x 1.2222 in the master gamma while you work, then take it off when you render to DPX. I didn't quite get the right result using FCPLUT.mga, but this way I got the consistent results (not saying that FCPLUT don't work).

 

[Ido Karilla]

kona 3

kona 3

Ggrading on an sdi out of the kona 3, the Lut is essential. The lut fixes the gamma shift FCP creates compare to color ( with the kona 3 everything in FCP is a little bit more open compared to color).

 

[Evangelos Achillopoulos]

Thanks Ido... updated the original post.

 

[Jan Bull]

Does anybody have an answer to what Brian asks in this thread?
"Also, does anyone know why the levels change in Final Cut when you're playing footage as opposed to scrubbing it or when it's stopped"
Would be nice to know

 

[danbrazda]

Blackmagicdesign and MXO output 1.8 (or no gamma applied) from Color when RGB material on the timeline.

So, you'd want the Blackmagic LUT to be set with x 1.2222 in the gamma section for the monitoring, but when Color outputs DPX files, Color makes the change to write the files with 1.2222.. gamma shift.

So you grade in color and then on output add the 1.222 master gamma? Or are you saying you grade in Color with the Master Gamma set at 1.222?

 

[Robert Monaghan]

If you want to bring in the DPX to FCP, at this time I'm conforming manually (dough!, hope bob from Glue Tools comes out with this support soon)

I am working on it.. Its a complicated process.

bob.

 

[Kaku Ito]

So you grade in color and then on output add the 1.222 master gamma? Or are you saying you grade in Color with the Master Gamma set at 1.222?

Sorry for late replay, I missed this one.

If you are outputting R3D native files as DPX from Color, you would want to only "look" with 1.226 applied but don't apply upon rendering. This is because Color takes RGB material as 1.8 gamma then output as 2.22. Contrary, in case of handing R3D in Color then output as QT, then you need to apply the master gamma of 1.226 since Color tries to output as gamma 1.8, thus your material would be matched to 2.22.