GH5 how to set the Luminance for UHD video?

[Adriano Moroni]

Hi, I have always had a doubt about Luminance and would like to ask a question.
I only make UHD videos with the GH5.
I have 2 options in the Settings regarding Luminance:
0-255 or 16-235 for 50p and 8bit
0-1023 or 64-940 for 25p and 10bit
Can you advise me which one you would use?
But does anything change when watching video on TV?
Thank you

[Keith Rollinson]

First you choose 8bit/50p, or 10bit/25p - I'd choose the latter for quality.
Then - is your FINAL destination for television or computer/web display? If for TV, choose legal range (16-235 or 64-940), or for computer/web full range (0-255 or 0-1023.) Peak whites and blacks display differently on a TV vs. computer, hence the different values. If you want to know more, tons of docs you can search on the web.

[Adriano Moroni]

I thank you for your precious news. Please, clear my ideas, because I still don't understand well
I will only watch my 4K video on a large 65" TV
I now give an example:
1) On sunny days, 50p 8bit UHD. Do I have to choose 16-235
2) On sunny days, 25p 10bit UHD. Do I have to chhose 64-940
Are they right? Did I understand well?
I thank you again.

[Christopher Young]

How I see it and work.

It really depends where your footage is going whether you use the 16-235 or 64-940 levels. If you were going to have to go live to air with a camera then that 64-940 would be the appropriate setting to use as that meets broadcast "Video" 709 standards. That's the level used on broadcast TV cameras.

For all intents and purposes, you might as well work 0-255 or 0-1023 if the footage is going to be edited for any kind of delivery medium. In Resolve, for example, regardless of the levels of the footage coming into Resolve be it 0-255, 16-235 0-1023 or 64-940 Resolve will convert it all to data levels of 0-1023. Any incoming 0-1023 footage will remain at 0-1023 as that is the data level range that is used internally by Resolve. If you are working in a video level timeline the scopes will read 0-1023 even though what you are actually seeing is a 64-940 range. Basically in broadcast terms, this Resolve 0-1023 range is equivalent to the broadcast IRE range of 0-100. In 10-bit that's a data range of 64-940 or in 8-bit 16-235. Or on the other hand, you could be grading for HDR with HDR scopes. Whichever way you look at it the internal Resolve data levels will always be 0-1023. When you have finished your edit and want to deliver your program, again let's say in Resolve you would on the Delivery page make sure under "Advanced Settings" that your render setting was set to "Video" as this "Deliver" Tab setting is what determines your final levels be it Video or Data. 99% of the time it would need to be "Video".

In a nutshell, quoted from "thepostprocess":

Files exported for broadcast should be video levels. Most of the time broadcasters require Rec709 ProResHQ 4:2:2 which is video levels.

Files exported for the internet should be video levels. Most codecs that are used for file delivery are video levels not full. Encoders expect video level files for most delivery formats.

Exporting files using video levels WILL NOT lead to your files looking washed out. Exporting files using full levels WILL NOT make your files look better or more accurate.

Even though your computer display is RGB, video level files will look correct on your screen because players will scale the values correctly.

https://www.thepostprocess.com/2019/...full-vs-video/

Summing up. I would only shoot 64-940 for live or for files that are going straight to air when there is no time for level adjustments. Check out the attached images from the EBU for a bit more clarification.

https://tech.ebu.ch/docs/r/r103.pdf

Chris Young

[Adriano Moroni]

You have been very kind and very professional. You have responded in detail to all shooting situations. You have been very, perhaps too professional. ;)
I don't care at all nor about "to air with a camera" and neither "Files exported for the internet".
But it's my fault, my inexperience. I apologize for this.
I'd like to shoot videos with my GH5 in order to get the best video in UHD and then to do public projections with small groups of people. I have a Sony Bravia 4K 65 "TV.
So for me the most important thing is to know how to set my GH5 with Luminance.
From what you wrote, I understand that if I film 50p 8bit UHD I can use 0-255 Luminance.
If I film in 25p 10bit UHD I can use 0-1023 Luminance. OK?
I export from Edius to HEVC, then I put my files in a HDD and I use Shield TV Pro to whatch them by HDMI cable.
Again, I' like to choose the best luminance in my GH5 in order to get a great video to watch on a large TV.
Thank you.

[Ron Evans]

The brightness of the image when you play it back on TV or projector is not governed by the luminescence range on the GH5 it is dependent on how you set the exposure when you shoot the video and how you edit the video. Choosing different ranges will give you more recording range but not how bright it looks after editing.

You can use the scopes in editing to identify how bright or dark the image will be when displayed. Open the scopes in EDIUS and use PCC exposure control or YUV to set how bright the image will be when displayed. I have my GH5's set to 0 - 255 ( since I shoot 60P UHD internal it is 8 bit ) as it is easy to get in range when editing. For shooting Vlog it is always set by default to 0- 255.

[Christopher Young]

Originally Posted by Adriano Moroni

From what you wrote, I understand that if I film 50p 8bit UHD I can use 0-255 Luminance.

Yes shoot 0-255 or 0-1023 and edit full range and export full range from Edius. Your Bravia will, or should automatically detect the video range in the file and switch accordingly. Most flat panels from most manufactures will auto detect levels. Also most flat panels do allow you to manually set the data range under menus like HDMI content and HDMI RGB range for each input. For your own use using either 0-255 or 0-1023 should work well and squeeze out about the best image and dynamic range you can get. Bear in mind though most HDR sets still don't have more than around 10-11 stops of display latitude. Modern cameras like yours these days can deliver better than 12 stops. You only need to worry about 16-235 and 64-940 if you are delivering to clients. The best thing to do there is qualify with your client where the videos are to be viewed. If they have no idea, like most of my non-broadcast clients play it safe and deliver "Video" levels.

Chris Young

[Adriano Moroni]

May be my english is bad, but no one has yet told me the luminance level i can use with 25p 10bit UHD.
I will use 0-255 Luminance with 50p 8bit UHD GH5 settings.It is OK!!
What can I choose with 25p and 10bit GH5 settings?
Is it the same Luminance level?
Thank you!

[Christopher Young]

0-1023 for 25p and 10bit.

Chris Young :)

[Adriano Moroni]

All that even with CNED (Cinelike dynamic range)?
Thanks so much. ;)

[Ron Evans]

The numbers represent the sample in 8 bit or 10 bit 0 is black and for 8bit white is 255 and for 10bit white is 1023.

[Keith Rollinson]

Whoa - to be clear:
8 bits - 16-235 (legal range) or 0-255 (full range)
10 bits - 64-940 (legal range) or 0-1023 (full range)

Broadcast TV is legal range; computer display is full range. Computers can display a wider gamut from black to white; hence the extended numbers. Most important is to know your final destination -legel or full - and that your post production maintains whichever range environment you choose.

[Doug Jensen]

It really comes down to this: If you're going to edit the footage anyway why the hell would you impose limitations on the footage at the time of shooting?? Why impose artificial limitations if you don't have to?
Use 0-255 or 0-1023 unless you are literally going to to straight from the camera to air. If you're going to edit, then any NLE is capable of allowing you to bring levels into legal levels for delivery.Why shackle yourself at the time of shooting?

A still photographer you who knows he's going to have to deliver JPEGs to the client will still shoot RAW to ensure they are shooting the best image possible, even if it has to be dumbed down for final delivery. This is the same thing. Record the best quality the camera is capable of, and then dumb it down as necessary for final delivery.