Is there any way to 'read' the colour space of a video clip?

Basically wondering if there are any apps (maybe even Resolve?) which can look at a clip and and say what colour space it seems to have been graded/encoded in or output a gamut graph.

For example if you download a clip that is Rec2020 but you didn't know this - apart from visual cues is there any way to be sure what colour space it is in?

I'm on a Mac but the quickest way I know is to just look at the file info in its properties. It shows the color space there. VLC media player is also multi-platform and shows that in the Media Information-Codec Details window.

Erich

Basically wondering if there are any apps (maybe even Resolve?) which can look at a clip and and say what colour space it seems to have been graded/encoded in or output a gamut graph.

For example if you download a clip that is Rec2020 but you didn't know this - apart from visual cues is there any way to be sure what colour space it is in?

I like mediaInfo.

Do these programmes show anything beyond RBG/YUV? Are they actually capable of showing 709/2020/some form of log?

You can't deduce color space from video data only. Unless you know for sure that there is no creative grade applied whatsoever (only straight technical transforms) and you have some reference data like a color chart in the shot. Then maybe you can make an educated guess.

It is probably easier to guesstimate the transfer function than gamut, but it is still a guess. A milky flat footage can be normal log image but it can also be a creative grade. There is no meaningful way to tell which is which unless you have some additional info.

Some stuff is a bit easier to ballpark, for example (viewing data as-is on rec709) unnaturally green image could be XYZ data, milky flat stuff is some kind of log, unnaturally dark and contrasty is maybe linear data. But you still don't know squat about gamut (except XYZ case) because you can't tell wide gamut from simply undersaturated image.

Do these programmes show anything beyond RBG/YUV? Are they actually capable of showing 709/2020/some form of log?

Hi,

Unfortunately (or not?), There is no tool "miracle".

A bit of experience and why not: do tests when in doubt?
But normally: we know what we have to work: giving / giving. It's a minimum ...

Same clip, same metadata of MediaInfo and yet some differences depending on the settings ... (without corrections)

GH5S VLOG

Code: Select all

Complete name                            : K:\_Shots_Shots\GH5\GH5S\GH5S VLOG.MOV
Format                                   : MPEG-4
Format profile                           : QuickTime
Codec ID                                 : qt   2011.07 (qt  /pana)
File size                                : 3.55 GiB
Duration                                 : 3 min 20 s
Overall bit rate mode                    : Variable
Overall bit rate                         : 152 Mb/s
Encoded date                             : UTC 2018-03-03 17:59:26
Tagged date                              : UTC 2018-03-03 17:59:26
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Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High 4:2:2@L5.1
Format settings                          : CABAC / 1 Ref Frames
Format settings, CABAC                   : Yes
Format settings, RefFrames               : 1 frame
Format settings, GOP                     : M=1, N=12
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Codec ID/Info                            : Advanced Video Coding
Duration                                 : 3 min 20 s
Bit rate mode                            : Variable
Bit rate                                 : 150 Mb/s
Maximum bit rate                         : 180 Mb/s
Width                                    : 3 840 pixels
Height                                   : 2 160 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 25.000 FPS
Standard                                 : Component
Color space                              : YUV
Chroma subsampling                       : 4:2:2
Bit depth                                : 10 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.723
Stream size                              : 3.50 GiB (99%)
Encoded date                             : UTC 2018-03-03 17:59:26
Tagged date                              : UTC 2018-03-03 17:59:26
Color range                              : Full
Color primaries                          : BT.709
Transfer characteristics                 : BT.709
Matrix coefficients                      : BT.709


same as rec709 and panasonic VGamut_vlog.jpg

MediaInfo provides information and leads but is not "the real truth"

Basically wondering if there are any apps (maybe even Resolve?) which can look at a clip and and say what colour space it seems to have been graded/encoded in or output a gamut graph.

For example if you download a clip that is Rec2020 but you didn't know this - apart from visual cues is there any way to be sure what colour space it is in?

No!

The metadata may indicate what it is but it is not reliable because some apps do not automatically pass on the color space, primaries and transfer characteristics.

Code: Select all

Color primaries                          : BT.709
Transfer characteristics                 : BT.709
Matrix coefficients                      : BT.709


Actually I do not think that is wrong. V-Log-L's gamut, at least on the GH5(s), is Rec.709 not V-Gamut. Only the gamma is V-Log but limited to 79IRE.

V-Log-L's gamut, at least on the GH5(s), is Rec.709 not V-Gamut. Only the gamma is V-Log but limited to 79IRE.

i don't agree. i wouldn't assert, that the GH4/5/s are able to capture the full V-gamut color space, but they seem to use it's reference points indeed for V-log encoding resp. it's actual values.

V-Log-L's gamut, at least on the GH5(s), is Rec.709 not V-Gamut. Only the gamma is V-Log but limited to 79IRE.

i don't agree. i wouldn't assert, that the GH4/5/s are able use the full V-gamut color space, but they seem to use it's reference points indeed for V-log encoding resp. it's actual values.

Just use the standard V-Log/V-Gamut color transforms for GH5 and you will see on your monitor and the vectorscope that the corlors are too saturated due to the fact that v-gamut is larger than Rec.709.

Just use the standard V-Log/V-Gamut color transforms for GH5 and you will see on your monitor and the vectorscope that the corlors are too saturated due to the fact that v-gamut is larger than Rec.709.

that's indeed the expected behaviour! it's just the same as some log-footage after applying the necessary gamma translation, doesn't have to fit into the quite limited traditional rec709 DR range. if you want to adapt it to this more limited color spaces, it always needs some kind of tone mapping resp. gamut compression.

Just use the standard V-Log/V-Gamut color transforms for GH5 and you will see on your monitor and the vectorscope that the corlors are too saturated due to the fact that v-gamut is larger than Rec.709.

that's indeed the expected behaviour! it's just the same as some log-footage after applying the necessary gamma translation, doesn't have to fit into the quite limited traditional rec709 DR range. if you want to adapt it to this more limited color spaces, it always needs some kind of tone mapping resp. gamut compression.

That's nonsense, V-log/V-Gamut out of the EVA1 works just fine and shows correct colors, V-Log out of the GH5 does not.

By the way converting gamuts using Resolve mathematical transforms work just fine in Resolve, it is only the values that become out of gamut that need to be mapped to the smaller space.

Why don't you just try it yourself, you can see that the color space is Rec.709 instead of V-Gamut instead of arguing against what can be readily seen?

i'm more sympathizing with the rational explanation given here:

http://www.liftgammagain.com/forum/inde ... pace.8382/

i still use a GH4 for privat work, where VLog is even much less useful. that's the reasion, why i'm quite aware of this issues, because this V-Gamut translations resp. the involved quantification decrease has unfortunately at least the same destructive consequences as 8bit-Log recording + wasted Vlog-L values on the luma side in respect to the final color artifacts.

i'm more sympathizing with the rational explanation given here:

http://www.liftgammagain.com/forum/inde ... pace.8382/

I can't agree with the explanation in that topic even if sometime ago I had hoped the gamut is V-Gamut, it is simply a matter of seeing it on the monitor.

Also the problem with GH5's V-Log prevents it from being used effectively in an ACES workflow. If I use ACES with the GH5 I have a Rec.709 color neutralizing LUT as a workaround which can be used inside the ACES workflow to compensate for the incorrect colors.

Contrast the GH5's V-Log-L incorrect application of V-Gamut with GH5's HLG which does correctly use a wider color space (Rec.2020).

Also the problem with GH5's V-Log prevents it from being used effectively in an ACES workflow. If I use ACES with the GH5 I have a Rec.709 color neutralizing LUT as a workaround which can be used inside the ACES workflow to compensate for the incorrect colors.

unfortunately i have to agree with this summary!

from day one, when panasonic presented the fist implementation of VLog[-L] for the GH4 at a press conference, it wasn't compliant to the proclaimed VLog specification and all the available IDTs. this was quite obvious, because even the curves in the press portfolio did show empiric measurements, which unmissable documented the divergence:



i spend a lot of time to develop my own IDTs, to work around this shortcomings. so i could reproduce and understand this obvious incompatibilities much better after a while, but in practice i also couldn't realize any useful alternative, which really would work significantly better in practice. it's nearly impossible to compensate this kind of imperfectness just on base of empiric camera profiling resp. already processed video data.

i personally didn't trace the relevant debates and measurements in case of the GH5 anymore. maybe panasonic improved the VLog accuracy resp. specification compliance in the meanwhile -- i really don't know -- but i'm quite skeptic, cause of this earlier experiences...

At this stage, after much reluctance skepticism from my side, I would recommend using HLG over V-Log-L. The dynamic range may even be a bit better using HLG and at least it uses a standardized gamma curve and color space.

It now only waiting for ACES to hurry up and get their HDR take two out.

At this stage, after much reluctance skepticism from my side, I would recommend using HLG over V-Log-L. The dynamic range may even be a bit better using HLG and at least it uses a standardized gamma curve and color space.

It now only waiting for ACES to hurry up and get their HDR take two out.

I do not share much the idea of working in HLG with a clip that is in
<CaptureGamma> V-LogL </ CaptureGamma> /
<CaptureGamut> V-Gamut </ CaptureGamut> /

You do what you want but with the RCM + Use separate Color space
Panasonic V-GAMUT ICS / Panasonic V-LOG
and
TCS and OCS Rec.709 / Range 2.4, I find the correct result.

I do not share much the idea of working in HLG with a clip that is in V-LogL/V-Gamut

No-one obviously does!

When you have V-log footage from the GH5 I would use RCM with Rec.709 gamut and Panasonic V-Log gamma.

However now I favor capturing in HLG over V-log, there is better dynamic range and the colors are recorded correctly in Rec.2020.

I do not share much the idea of working in HLG with a clip that is in V-LogL/V-Gamut

No-one obviously does!

When you have V-log footage from the GH5 I would use RCM with Rec.709 gamut and Panasonic V-Log gamma.

However now I favor capturing in HLG over V-log, there is better dynamic range and the colors are recorded correctly in Rec.2020.

Yes, the HLG is much more practical.

Yes, the HLG is much more practical.

It's better.

Due to a better color management, a lower noise in the blacks and a better dynamic range.

See for instance the EBU assessment on the GH5s:
https://tech.ebu.ch/docs/tech/tech3335_s29.pdf

Try to record a saturated blue object in V-Log and HLG and compare the results using V-Log/V-Gamut against HLG the blue goes radioactive under V-Gamut. V-Log/Rec.709 by the way is not perfect either it needs some extra saturation.

In resolve you can easily convert HLG to your preferred timeline gamma/gamut.

Basically wondering if there are any apps (maybe even Resolve?) which can look at a clip and and say what colour space it seems to have been graded/encoded in or output a gamut graph.

For example if you download a clip that is Rec2020 but you didn't know this - apart from visual cues is there any way to be sure what colour space it is in?

Simple answer is NO. There is no 100% reliable way.
File metadata can be wrong and quite often is wrong.
You can look at gamut plots, but this is also not 100% reliable.

Cheers Andrew - what software are you using for that gamut plot out of interest?

Not many there- this is grab from GrayMeta Iris which is quite expensive.
DrasticTV has videoQC which also plots it if I'm correct. Much more affordable.

Thanks, they both have trials so easy enough to have a poke around!

You can look at gamut plots, but this is also not 100% reliable.

i don't think, such a plot resp. the distribution of values in an arbitrary image will tell you anything about the actual utilized color space!
you first need a relation between the actual colors in the captured scene and their representation in the analyzed data -- some kind of reference points -- e.g. by capturing color charts etc....

It's just an indication. It can be misleading for sure.

It's just an indication. It can be misleading for sure.

sorry, but it's IMHO completely misleading, because it only displays, how the actual color values of a given image are actually distributed resp. interpreted in an arbitrary guessed interpretation, but unfortunately it doesn't say anything about the actual utilized colorspace of the recording resp. its correct interpretation.

If you have file flagged and graded as Rec.709 then you expect all colors be inside Rec.709 gamut and they will be when you look at the plot (if all done correctly).
If you then manually interpret this file as eg. P3 then it will be all wrong, so this is again based on some correct flagging or you knowing how file was created. Otherwise it's useless.

Unless you have negative values in the image, all colors will always be inside whatever gamut you interpret it to be. So it is practically useless for deducing anything about gamut of unknown footage.