GH5 GH5: luminance level settings

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FoxAdriano

Well-known member
Hi, in the GH5 setting on "Luminance level" I see 3 options: 16-255 16-235 0-255. Does anybody can esplain their meaning and which of 3 I have to choose? Thanks
 
These values only apply to Rec709 (HLG and V-LOG L are always 0-255), in that case I would suggest 16-235 which is industry standard video levels.
 
I thank you for your info but ... I'm sorry I don't understand well because I'm completely inexperienced. If I don't use HLG and V-LOG L, do I have to use 16-235? But
practically if I whatch a UHD video shot with luminance 16-235 and another video with the same subject with luminance 0-255, in practice what is the difference? Thanks
 
Cary Knoop said:
These values only apply to Rec709 (HLG and V-LOG L are always 0-255), in that case I would suggest 16-235 which is industry standard video levels.
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No, actually, HLG is *always* at video levels. When in doubt, remember that it is a backwards-compatible broadcast standard.
 
FoxAdriano said:
Hi, in the GH5 setting on "Luminance level" I see 3 options: 16-255 16-235 0-255. Does anybody can esplain their meaning and which of 3 I have to choose? Thanks
Click to expand...

To oversimplify: broadcast standards allow some room at either end of the video signal for margin of error and to embed some extra non-visual data. (It's mostly a relic of old analog standards.) This more limited range is often called "video levels".

When acquiring an image (camera,) storing the image at video level causes you to waste some precious bits (especially precious at 8-bit where there are barely enough.) So if you can acquire a "full range, 0-255" then you have a little bit more information to work with in post. And if you're delivering for something like YouTube, then "video levels" don't apply, anyhow.

To further complicate things, some NLE's expect your file to be at video level, and if they encounter a full range signal, they "clip" it, causing highlights to look blown-out.

Long story short: The most foolproof thing to do is shoot at video levels, 16-235. If you know what you're doing in post, shoot 0-255. I don't know why the hell anyone would shoot at 16-255.
 
Cary Knoop said:
I stand corrected, thanks for putting that right!
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It's frustrating because there is no HDR option on the GH5/GH5s that uses the entire bit bucket. V-LOG L wastes an unconscionable amount of it to be "compatible" with V-LOG, and HLG wastes some of it to be "compatible" with archaic standards that are no longer relevant.

I wish that Panasonic had made different curves for different possible dynamic ranges: V-LOG 12, V-LOG 14, V-LOG 16, etc. that each used the entire possible signal.
 
joe12south said:
V-LOG L wastes an unconscionable amount of it to be "compatible" with V-LOG....
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But in defense of Panasonic they attempt to make the GH5 compatible with higher dynamic range cameras. If anything they are already stretching it.

Increasing the log range will wash out the colors if used in workflows with higher dynamic range cameras especially under ACES.
 
Cary Knoop said:
But in defense of Panasonic they attempt to make the GH5 compatible with higher dynamic range cameras. If anything they are already stretching it.

Increasing the log range will wash out the colors if used in workflows with higher dynamic range cameras especially under ACES.
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I don't think that logic is valid because:

- In a single camera workflow, it's a moot concern. The right input for the camera is the only necessary input whether a traditional LUT workflow or an ACES workflow (or a RCM workflow.)

- For a multi-camera project:
- In a standard LUT based workflow, it is easy enough to apply the right input LUT to the right camera.
- In a proper ACES workflow, it is SOP to apply the correct IT/IDT (Input Transform.)

The *only* scenario I can think of in which one log curve for all cameras is necessary is a broadcast scenario in which it is impossible for each camera to go through an individual LUT box. (And who would should log in such a scenario?) Otherwise, it's just a matter of sacrificing quality at the expense of convenience for a tiny minority who have to match a GH5 and a Varicam, and are too lazy to apply two different LUT/IT.
 
Legal/Video Levels is a curse, but as I don’t edit my footage, one I embrace.

Seen too many post houses, & editors, incorrectly interpret footage, & it always get’s blammed on the shooter, who usually off on another project. And for all practical purposes ProRes is Legal Range which can be an issue when utilizing a recorder, or transcoding.

Also too many monitors still expect Legal Range, & I’ve seen many a Video Village looking at crushed blacks, & clipped whites, which again reflects poorly on the shooter.

Choose your poison.
 
If you use monitors or any other type of video gear like video switchers or recorders then you will likely want to stick with the legal video range. If you shoot only in camera and never use an external monitor or other video equipment then 0-255 is perfectly fine as long as your NLE knows what to do with it. The ugliness of 16-235 vs 0-255 really comes into play for those recording externally. Most video capture devices expect a 16-235 signal and capturing v-log externally can kill the dynamic range of the video since the ends are clipped. Not really clipped but they look clipped. Most of that detail can be recovered with a few methods.

https://www.cinema5d.com/fix-crushed-blacks-on-sony-a7s-and-a7s-ii-external-recordings/
 
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