How to handle out of range video levels (GX80 / GX85 in Premiere Pro)

[Cary Knoop]

I made a small tutorial on how to handle out of range video levels in Premiere Pro.

Some cameras record out of range video levels, one of them is the Panasonic Lumix GX85 / GX80 on which this tutorial is based.

Hope this helps and please go easy on me, as this is my first tutorial.

The UHD should be available shortly as YouTube is still processing it.

 

 

 

[Inazuma]

Cary, I have to thank you for reminding me about this because I did actually forget about it. The easy way to fix the problem actually (in Premiere Pro anyway) is just to use the Fast Color Corrector and change the white OutPut Level frm 255 to 235.

Before:

After:

[Cinegain]

Good schtuff, so true! Reminds me of the video presentation by Larry Jordan, it's a bit dated and targets FCPX, but it's based on some good general principles:

On 11-5-2015 at 4:25 PM, Cinegain said:

I really dug this video I came across one time. If you want to skip a bit, try watching from 23:45 (skintones):

 

[kidzrevil]

2 hours ago, Inazuma said:

Cary, I have to thank you for reminding me about this because I did actually forget about it. The easy way to fix the problem actually (in Premiere Pro anyway) is just to use the Fast Color Corrector and change the white OutPut Level frm 255 to 235.

Before:

After:

Do you apply that before you start grading or after ? I've tried this before and recovered highlights but I am not sure if it is compressing from 0-255 to 16-235 and then stretching it back out to 0-255 on export. Huge mystery I hope someone can explain to me !

[Cary Knoop]

4 minutes ago, kidzrevil said:

Do you apply that before you start grading or after ? I've tried this before and recovered highlights but I am not sure if it is compressing from 0-255 to 16-235 and then stretching it back out to 0-255 on export. Huge mystery I hope someone can explain to me !

Exporting using RGB (full range) levels only happens when you export with codec options such as ProRes4444 or DNxHR. 

Most of the time you will export video levels.  Any good NLE will use 32bit or float internal representation so this is not really an issue.  I would recommend to always stick with video levels on export unless someone specifically requests RGB.

 

[studiodc]

12 minutes ago, kidzrevil said:

Do you apply that before you start grading or after ? I've tried this before and recovered highlights but I am not sure if it is compressing from 0-255 to 16-235 and then stretching it back out to 0-255 on export. Huge mystery I hope someone can explain to me !

All processing is done internally in 32-bit high resolution colour.

You'd do this before you start grading, to tell it how to interpret the footage (e.g. where to map the 8 bit signal into that 32-bit space). After that, until you export, it's in the very large 32-bit colour space. 

[kidzrevil]

@studiodc thanks man you just saved me from overthinking myself to death ! 

[zetty]

How it is possible that the GX80 records values beyond 255? That's more than 8 bits. Or does Premiere map 0-255 or 16-255 as if it was 16-235, pushing the values above 235 beyond 255?

[Cary Knoop]

1 hour ago, zetty said:

How it is possible that the GX80 records values beyond 255? That's more than 8 bits. Or does Premiere map 0-255 or 16-255 as if it was 16-235, pushing the values above 235 beyond 255?

The GX80/85 does not record values beyond 255, it outputs video levels (16-235) but it also records levels outside this range as overhead.

Premiere Pro maps both (legal) video 16-235 levels and full range RGB levels to 0-255 as it internally processes all video as RGB.  Illegal levels will be outside of this range and thus you can have values outside the 0-255 range.

 

[zetty]

So from what you said, GX80 does actually record 16-255 or 0-255, and Premiere maps it as if it was 0-235 or 16-235.. which seems to be an incorrect interpretation of the data as what's the point extrapolating 235 to 255 and the real values in that range put beyond 255.. 255 is still "illegal" for broadcast anyway.

[Cary Knoop]

2 hours ago, zetty said:

So from what you said, GX80 does actually record 16-255 or 0-255, and Premiere maps it as if it was 0-235 or 16-235.. which seems to be an incorrect interpretation of the data as what's the point extrapolating 235 to 255 and the real values in that range put beyond 255.. 255 is still "illegal" for broadcast anyway.

No, Premiere Pro interprets the information just fine. Many cameras do record out of range values for overhead. By the way Davinci Resolve will do the same with video levels.  In Resolve you also would need to bring down the overhead values into legal.  But Resolve does not have the 'Clamp Video Signal' so you have to look and see if there are out of range values.  You could as an alternative force data levels in Resolve.  I would recommend always to check for overhead when you are dealing with video levels.

The values in the scopes are just scales superimposed on the data. If that confuses you I would recommend to only look at the percentage/IRE scale on the left. 

If you import multiple clips where some are video and others use full range Premiere correctly maps all of those onto the 0-100% scale.  But out of range values (which obviously are not possible for full range) will be mapped outside of that range.  Which means that levels outside the 0-100% range need to be brought into legal range.

 

[zetty]

Thanks for the explanation. So I guess the "overhead" values that the camera records must be in the 235-255 range, meaning it is in fact recording up to 255 but marking the files as 16-235 (which is the 100% for the format).

Good to know, as I'm about to invest in GX80 as a B/backup cam.

[Cary Knoop]

4 minutes ago, zetty said:

Thanks for the explanation. So I guess the "overhead" values that the camera records must be in the 235-255 range, meaning it is in fact recording up to 255 but marking the files as 16-235 (which is the 100% for the format).

Yes, exactly! 

The Panasonic GX80/85 is not the only one, I think the many of the Sony cameras do a similar thing. 

Always check when you edit clips with video levels for out of range values!

 

[Vesku]

I see lots of videos in Youtube with lost superwhites. I can see those clipped highlights when streaming Youtube videos through a player (Potplayer) and adjusting output levels. I think many using Premier or Premier Elements dont figure how to save superwhites or superblacks from their camera to final video. Some video editors like Magix converts automatically different video levels to rendering levels. I wonder why Premier has no easy setting for that.

[Vesku]

I studied Sony RX100 mk3  files with Vegas Pro scopes and it gives different values than Premier. Vegas shows RX100 XAVC-S is 16-255 and Premier shows 0-255. I saw odd readings with my GH4 files in Premier too. Premier Waveform shows 16-235 with my GH4 0-255 files. My eyes says the Vegas Waveform is right. Is there some settings in Premier causing wrong values in Waveform.

It is also confusing to view videos with PC Media players. If I play full range 0-255 video I must set graphics card level setting to "limited range 16-235". If I use normal 16-235 video I must set graphics card setting to "full range 0-255".

When I watch GH4 full range 0-255 video file with "limited range 16-235" setting the final video image in monitor contains all the 0-255 shades and it is perfect and has no banding.

When I watch "normal" 16-235 video with "full range 0-255" setting the final video image in monitor has only 235 shades stretched to 255 monitor and the result lacks about every 6th shade causing banding and noise. If I use 16-235 video with 16-235 setting the gradations are perfect but the whites and blacks are gray.

One problem is that many cameras record 16-255 levels but there is no setting in graphics card for that. I can use my video players additional settings for levels for 16-255.

There is no way to watch full range videos with TV players. TV player always clips everything outside 16-235. Many cameras record full range video like Canon DSRLs and Olympus mirrorless and some Panasonics like GH3 and GH4.

Here is a rough example what happens when watching normal video.

 

 

 

[Vesku]

What is actually video level "flag"? Inside video file is somewhere VUI (video usability info) flag for full range or limited range. Can I see the VUI flag somehow? Is it in video exif? What a player or editor does with that flag? Does the Premier do something when a file has a flag? Is there always a level flag in video file?

Video level setting in graphics card is confusing when I want to watch full range video:

 

[Vesku]

Is this a good way to automatically "legalize" rendering output?

https://www.linkedin.com/pulse/legal-luma-chroma-levels-premiere-pro-cc-2015-simon-walker