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How Important is 10-Bit Really?


Mark Romero 2
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3 hours ago, Vesku said:

 

Panasonic GH5 actually can shoot 8 bit HLG 4k 30P when using a special trick. I think it is a bug which allows 8 bit HLG but only in 30P.

When I save 4k 60P in C-memory and then select record mode HEVC the camera uses h.264 8bit 4k 30P 100Mbs but allows HLG.

so the only camera that can shoot in hlg on market is the gh5 and it does it thx to a bug?

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3 minutes ago, Dan Wake said:

so the only camera that can shoot in hlg on market is the gh5 and it does it thx to a bug?

No, the GH5, the GH5s, the Sony a7r III, the a7 III and others shoot HLG as well. Vesku was just pointing out that there’s a way to shoot 8-bit HLG on the Panasonic.

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Fun fact our cameras store data in a linear fashion but our eyes see color data logarithmically. You can store a 14 bit - 16 bit linear data in a 10bit logarithmic curve as proved by Cineon since its conception. If this is the case then 8 bit log (lets use SLOG) as an example is storing the 14 bit linear data from the sensor and maps the code values to an 8 bit logarithmic curve to be decoded later. I think why we feel we need 10bits is because of the software we used to use or our reliance on luts which are hard coded to a very limited amount of transformations. I recently changed my workflow from using luts to a 32bit floating point color space like ACES and davinci resolve color management and the difference in image quality is night and day from using those hard coded luts that do weird things to an 8 bit image. Combine that with neat video which literally creates new pixels in 32 bit floating point and PROPERLY exposed video to take advantage of the code values from 0-255 and you get an extremely pleasing image. Image resolution also helps with color depth so 4k 8 bit makes the 10 bit argument less and less of a factor hence why sony is sticking hlg curves in 8 bit cameras. Another fun fact you can convert a log curve like SLOG2 to HLG or REC2020 using a color managed workflow. I have totally abandoned luts

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26 minutes ago, kidzrevil said:

the difference in image quality is night and day from using those hard coded luts that do weird things to an 8 bit image

LUTs as a tool are not the problem, but poorly built LUTs are. If you have a LUT with very smooth transitions, and your 8bit footage still breaks with it, Resolve's color management won't save it either. And what do you mean by "very limited amount of transformations"?

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@Attila Bakos I agree that poorly built luts can be problematic but pretty much what I am saying is the typical high quality 64 cube LUT from a brand like deluts,visioncolor and koji does not have anything close to the amount of mathematical transformations as a wide color gamut 32bit floating point color space like ACES or Davinci Resolve does . The math is just way more complex than the adjustments hard coded into the lut. This is part of the reason why the same LUT affects the image in different and sometimes unwanted ways because LUTs are dependent on the source footage. I do know however that tetrahedral interpolation in a program like resolve tremendously improves the accuracy of LUTs

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1 hour ago, kidzrevil said:

Image resolution also helps with color depth so 4k 8 bit makes the 10 bit argument less and less of a factor hence why sony is sticking hlg curves in 8 bit cameras.

Glad to know somebody gets it!

 

1 hour ago, kidzrevil said:

I have totally abandoned luts

I don't use luts in grading, but a lut can help with "client preview" on set.

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9 minutes ago, kidzrevil said:

I do know however that tetrahedral interpolation in a program like resolve tremendously improves the accuracy of LUTs

Yes, and even though you are right about the precision of pure math, a 64 LUT with good interpolation is more than enough for most people. I created size 64 LUTs that transform color space, gamma, and color, all in one, and the result was visually identical to the version where I applied the transformations one by one, each one with a size 64 LUT. But I wouldn't go lower than 64 if precision was needed.

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@Attila Bakos have you ever tried using aces or resolve color management ? The precision is beautiful try it out. I agree 64 will be enough for most people but these advances in tech shouldn’t be ignored. This is a large part of the reason why people think they need 10 bit, its cause their post production pipeline is outdated. The only way to properly do color space conversion with a LUT is with tetrahedral interpolation but most people are using the default trilinear interpolation which is not accurate at all for color space from lets say LOG to rec709

https://blogs.mathworks.com/steve/2006/11/24/tetrahedral-interpolation-for-colorspace-conversion/

 

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5 hours ago, jonpais said:

No, the GH5, the GH5s, the Sony a7r III, the a7 III and others shoot HLG as well. Vesku was just pointing out that there’s a way to shoot 8-bit HLG on the Panasonic.

so HLG is basically as if the camera is shooting in dual ISO? thx

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21 minutes ago, Matthew Hartman said:

I sure wish this conversation could be a little more laymen. :)

Lmao ! Basically I think you should master your footage in resolve color management or aces using davinci resolve. Grading like this you can get an accurate conversion of 8 bit LOG (slog2 etc.) to our displays color space without needing 10 bit to avoid banding etc

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8 minutes ago, kidzrevil said:

Lmao ! Basically if one can you should master your footage in resolve color management or aces using davinci resolve. Grading like this you can get an accurate conversion of 8 bit LOG (slog2 etc.) to our displays color space without needing 10 bit to avoid banding etc

Yes, I've been transitioning/learning Resolve for color grading just for the advanced tool set over Lumentri. Color separations and qualifiers are very powerful tools.

I have an NX1, and soon I'm picking up the Ursa Mini pro 4.6k possibly even this weekend. So are you saying the advantages you're referring to only apply to Sony slog2 in Resolve? I assume shooting with the Ursa will put me in the advantage of the 10/12 bit space and put me where the future is headed? 

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@Matthew Hartman I wish I still had my nx1 ?

ACES & RCM work with other camera profiles too. There is a generic rec709 conversion option but it doesnt work as well as I hoped. ACES has profiles for BMDfilm,alexa log c, all the slog’s and clog as well and its all done in 32bit precision. I still grade in lumetri I just use resolve ACES too color correct in a big color space without worrying about color channel clipping

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1 hour ago, kidzrevil said:

@Attila Bakos yeah bro not enough math within the space of the 64 cube for color conversion but they work better with rec709 in to rec709 output workflows

I wanted to see this for myself so I took two examples, both are 8bit Rec.2020 F-log. All I did was a color space conversion to Rec.709 and I added some contrast/saturation. In the first picture the conversion is done by a 64 LUT, in the second it is done by Resolve. Everything else is equal.

2_colorspace_lut.thumb.jpg.d935d52e9084a5a32a4af954c3d92dfa.jpg

2_colorspace_resolve.thumb.jpg.df5c5c23398b24523fa6d7ef5e51b156.jpg

I see absolutely no difference here. Now let's see some more reds, that's usually more telling.

1_colorspace_lut.thumb.jpg.7a9ac418b37226c5564a9512ae161bf4.jpg

1_colorspace_resolve.thumb.jpg.6216501a59f3c0e8c692ecdff476d9ea.jpg

There is a very slight difference when you look at the harp, but that's it.

I'm not a professional colorist, but the result of the LUT would be precise enough for me. And this is trilinear, not even tetrahedral!

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Rec2020 Flog ? From a Fuji ? You sure thats rec2020 ? @Attila Bakos

If it works for you thats cool, I just wouldn’t do it. Maybe in these situations it looks good but I’ve had out of gamut colors look weird with LUT’s especially with artificial lighting so I stay away from those things. A lut has to be calibrated for specific exposures while floating point does not 

https://lutify.me/essential-steps-in-color-grading-when-using-luts/

 

57EAA5B2-E42F-4C0A-B7A5-44825DE5C4B2.png

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