Author Topic: Wide Gamut WF and HDR/DualISO/AutoETTR (newbie's chaos)  (Read 1255 times)

adrjork

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Wide Gamut WF and HDR/DualISO/AutoETTR (newbie's chaos)
« on: April 29, 2018, 01:36:11 AM »
Hi everyone,

As I wrote many times, I'm a self-taught newbie, and I "use" forums to clarify my messy ideas. So, sorry for my basic a chaotic quesions, but I think that probably other guys could be in my condition and could find useful clarifying this topic:

Since I'm an happy user of Magic Lantern's RAW video, I'd like to understand better the concepts of wide gamut and HDR footage. What I hope to have understood is that HDR refers to light, while gamut refers to color: two different things, but I'm interested into how they are related.

Now, my camera (5D3) is set on AdobeRGB, and I shoot videos in RAW. I've read (in this forum) that RAW footage captures more infos even than AdobeRGB, so it should mean that RAW footage has yet wide gamut (perhaps not Rec.2020, but it should be at least as wide as DCI-P3 or even more). So, simply shooting in RAW should let me work in wide gamut workflow. (Right?)

Now, in order to obtain a wider dynamic range, Magic Lantern offers at least 3 tools: HDR, DualISO, and Auto ETTR. More or less, I should have understood that HDR is a tripled-frame capturing to obtain high dynamic frames to both raise shadows and prevent highlights clipping at the same time (right?), while DualISO should do the same thing but this time through a dual-frame capturing and reducing vertical definition (right?), while Auto ETTR should maintain the "distance" between shadows and highlights, raising the shadows and clipping a bit the highlights that are still recoverable thanks to Davinci "recover highlights" button (right?)
Now, these three methods are different, but it seems to me they are oriented to a similar purpose: obtaining the widest dynamic range.

What I hope to have understood is that both HDR RAW and non-HDR RAW videos are good for wide gamut workflow. (right?)

Now, can we consider DCI-P3 a wide gamut color space? I'm interested into this because I'm going to try coloring a video work for a theatrical premiere. Anyway, to handle a DCI-P3 10bit work, I should have a 10bit P3 compatible monitor: for example Eizo CG2730 declares true 10bit and 98% P3. But if I want to use Eizo as preview monitor, and work at 10bit, I have to use a PCI Decklink Mini Monitor, and this brings me to a problem: Decklink can handle only Rec.709 color space. So my question is: how can I take advantage of Eizo's many profiles if Decklink can handle only Rec.709? The same thing for AdobeRGB: my camera is set to AdobeRGB, and Eizo can handle it at 99%, but again Decklink can't handle it, so if I would like to have a correct preview of my footage in its native color space, what should I do? (A Quadro card? I'd hope there is a much more cheap solution... because it should mean using my Titan X fog GUI monitoring, and a Quadro for preview monitoring? Possible something cheaper?)

Thanks a lot.

50mm1200s

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Re: Wide Gamut WF and HDR/DualISO/AutoETTR (newbie's chaos)
« Reply #1 on: April 29, 2018, 07:10:43 PM »
Andy600 could answer better, but:

What I hope to have understood is that HDR refers to light, while gamut refers to color: two different things, but I'm interested into how they are related.

HDR refers to dynamic range, or, how many shades of gray you can obtain between black and white. Gamut, from what I know, is how many colors you can digitally represent.

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Now, my camera (5D3) is set on AdobeRGB, and I shoot videos in RAW.

The colors space configured inside the camera will have no effect on Raw images (including MLV, of course). Raw don't have a color space assigned to it. It's up to the software you're using to process it.

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I should have understood that HDR is a tripled-frame capturing to obtain high dynamic frames to both raise shadows and prevent highlights clipping at the same time (right?),

I don't think there's a feature like that in MLV recording... there is? I think you're confused with the h264 "HDR" recoding.

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while DualISO should do the same thing but this time through a dual-frame capturing and reducing vertical definition (right?)

DualISO uses different sensibilities on each line on the sensor. So, the result is a image with two different exposures at the same time, in the same frame. Then, it gets interpolated to create a image with higher dynamic range.

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while Auto ETTR should maintain the "distance" between shadows and highlights, raising the shadows and clipping a bit the highlights that are still recoverable thanks to Davinci "recover highlights" button (right?)

ETTR is "expose to the right". So, what this does (and you don't need magic lantern to do it), is get more light to be captured in the camera (generally 2 f-stops more than normal). With more light, more information. On post-processing, you can reduce the exposure and get a normal image, but with more information/less-noise in shadows.

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Now, these three methods are different, but it seems to me they are oriented to a similar purpose: obtaining the widest dynamic range.

Yes.

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What I hope to have understood is that both HDR RAW and non-HDR RAW videos are good for wide gamut workflow. (right?)

What do you mean by "non-HDR"? 10-bit and 12-bit raw?
But, yes, Raw information is not limited to any color space.

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Now, can we consider DCI-P3 a wide gamut color space? I'm interested into this because I'm going to try coloring a video work for a theatrical premiere.

I don't have the answer, but the new "best practice" seems to be ACES.

adrjork

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Re: Wide Gamut WF and HDR/DualISO/AutoETTR (newbie's chaos)
« Reply #2 on: April 29, 2018, 10:28:12 PM »
Wow, 50mm1200s, thanks really a lot!

I'll give a look at some ACES tutorial trying to understand something.

dia3olik

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Re: Wide Gamut WF and HDR/DualISO/AutoETTR (newbie's chaos)
« Reply #3 on: April 30, 2018, 08:27:42 AM »
BTW BMD cards can handle more than REC709...you can set it from the Resolve panel...

adrjork

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Re: Wide Gamut WF and HDR/DualISO/AutoETTR (newbie's chaos)
« Reply #4 on: May 01, 2018, 04:50:55 AM »
BTW BMD cards can handle more than REC709...you can set it from the Resolve panel...
Thanks for your reply. You are right, infact BM-support replied to me saying that the cards can handle P3 too. It's strange that in specs, 609 and 709 are the only two color spaces declared... I don't know why :)

ibrahim

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Re: Wide Gamut WF and HDR/DualISO/AutoETTR (newbie's chaos)
« Reply #5 on: April 05, 2019, 03:37:16 AM »
What display is the best to color grade 14-bit uncompressed cinemaDNG, DCI-p3 or rec2020.
Is DCI-p3 enough to display all the bits or should I choose rec2020?
Canon 5D Mark IIIs & Canon 600d | Ronin-M | Rokinon 35mm T1.5 Cine AS UMC | Samyang 85mm T1.5 UMC AS Cine VDSLR II   | Canon EF 24-105mm f/4L IS USM | Canon EF 50mm f/1.8 II | etc
Dual sound system: Tascam DR-60d MKII | Audio Technica AT899 | Sennheiser MKE 600

Luther

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Re: Wide Gamut WF and HDR/DualISO/AutoETTR (newbie's chaos)
« Reply #6 on: April 05, 2019, 04:22:54 AM »
What display is the best to color grade 14-bit uncompressed cinemaDNG, DCI-p3 or rec2020.
Is DCI-p3 enough to display all the bits or should I choose rec2020?

The best ones are probably Dolby PRM-4220 or Sony BVM-HX310. They are not affordable, though. I heard BenQ does decent monitors with affordable prices.
As far as I know, no monitor today has 100% coverage of Rec.2020.

If you're looking for precision, make sure you calibrate your monitor. See ColorMunki or similar devices. Also, most colorists recommend you use a wall painting of 18% gray and room artificial lighting using 5500K lamp with high CRI (>90 - see this link). This is to avoid some vision adaptations that can "distort" the perception (read Purkinje effect and Kruithof curve).

ibrahim

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Re: Wide Gamut WF and HDR/DualISO/AutoETTR (newbie's chaos)
« Reply #7 on: April 05, 2019, 05:35:39 AM »
Those prices are way above my budget.  :D

Say I want to send a film to a film festival that demands a DCP or Apple prores file. Am I better off buying DCI-p3 or rec2020 monitor if I am color grading in 14-bit cinemaDNG and in which working space should I set my NLE in AE or davinci, P3? rec709 or rec2020?

Canon 5D Mark IIIs & Canon 600d | Ronin-M | Rokinon 35mm T1.5 Cine AS UMC | Samyang 85mm T1.5 UMC AS Cine VDSLR II   | Canon EF 24-105mm f/4L IS USM | Canon EF 50mm f/1.8 II | etc
Dual sound system: Tascam DR-60d MKII | Audio Technica AT899 | Sennheiser MKE 600

Luther

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Re: Wide Gamut WF and HDR/DualISO/AutoETTR (newbie's chaos)
« Reply #8 on: April 05, 2019, 07:20:03 AM »
Those prices are way above my budget.  :D

Indeed. Scary prices.

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Say I want to send a film to a film festival that demands a DCP or Apple prores file. Am I better off buying DCI-p3 or rec2020 monitor if I am color grading in 14-bit cinemaDNG and in which working space should I set my NLE in AE or davinci, P3? rec709 or rec2020?

I'm not an expert, so don't quote me on anything I'm writing... that said, it depends on where you'll screen it. If you are going to be compliant to the UHD standard, your master format should be Rec.2020. I would recommend you do that, as most of the streaming services now support UHD standard and if you need to convert to Rec.709 8-bit it's very easy (the other way around is not).
Buy a monitor that has a big P3 coverage. As I said, as far as I know, there's no monitor today that has full Rec.2020 coverage and P3 is not so far from it.
About the 'working space', you should set ACES and then set the ODT to what you want (Rec.2020). Netflix has a tutorial here and more color grading resources here. I suggest you use ACEScct, as it simulates log.

ps: if you have $900 bucks, this one seems to fit what you need - https://www.bhphotovideo.com/c/product/1308752-REG/benq_pv270_27_led_monitor_2560x1440.html