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GH5 to Alexa Conversion


Sage
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@Attila Bakos Very cool, I was on a 3770k; I switched to Ryzen last year for this very purpose. Now I'd like to swap out to one of the newest Ryzens, but they are sold out everywhere. I'm doing something atm wherein I throw enormous amounts of data in, and the renders can easily go upwards of an hour at 100% cpu. My data files are usually around 1Mb per each; these are going upwards of 50Mb atm

@zerocool22 CST is a versatile tool that allows whitepaper transforms between any two spaces. These are the manufacturer specified color spaces. Emotive is a measured conversion between two cameras (or profiles etc), such that it factors in sensor response to a light source and internal camera processing (of WB, profile, etc). Emotive has simulations of sensor LogC solely using Resolve color tools (sans CST) called Matrix. Both the interpolated conversions (with Tetrahedral interpolation enabled) and the Matrix LogC simulations are non-destructive, while Arri's Rec709 (that can be added to Matrix LogC) is partly destructive (of extreme Led gamut). CST can be either destructive or non-destructive, depending on the transform specified and relevant gamut.

CST + Arri 709:

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Emotive Color

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I usually work with Alexa footage that's shot at one of three presets (3200K, 4300K, 5600K). Sage’s LUTs work really well, but getting the best match requires white balancing both the S1 and Alexa to neutral white before converting. Alexa white balance presets are not neutral–they're orange/green.

I wanted equivalent white balance presets I could use (5600k, 4300K, 3200K) with the S1, where I could shoot V Log, apply Sage's LUT, and get a ballpark match to Alexa presets–even if it might be a little less precise than doing this the right way.

I lit a white card with a Luxli RGBW light at 3200K, 4300K, and 5600K and then shot Alexa footage shot at 3200K, 4300K, and 5600K presets.

Then I shot the same with an S1 and and applied Sage’s Log C conversion LUT. I adjusted the white balance settings manually until I got a good match.

I've only tried out the 5600K preset so far in the field but it matches pretty well.

K1: 5600K A: 6 G: 9 (should be G: 10, but it doesn't go that far) – apply Daylight Log C conversion 

K2: 4300K A: 6 G: 6 – apply 4200K Log C conversion

K3: 3200K: A7: G: 4 – apply Tungsten Log C conversion

Beyond that, a bit of extra noise and a bit of unsharp mask after downscaling S1 4k to Alexa 2k/3.2k (amount 24, radius 3) also helps make S1 footage look more like Alexa footage. 

If this isn’t for you, ignore this post. It's not as precise as doing things the right way but for my needs is much more convenient.

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  • 4 weeks later...
On 12/19/2020 at 10:25 PM, Sage said:

Lol @ the ending

Hi @Sage, I hope you've had a great new year so far, I have used the s1alex lut on various personal projects now, gotta say I love the colors that it gives me, much more consistent and pleasing results even in warm or weird lighting compared to the p4k version. But the exposure seems to be quite a bit brighter than the normal rec709 lut. And the lut shows a lot more noise and artifacts then I expected especially at the higher iso gain. I have tried to reduce the exposure using the exposure adjustment luts, but on darker shots it clips the shadows and doesn't roll them off naturally like the braw exposure adjustments. Any advice on how to reduce the noise and artifacts without using noise reduction? (PS: I am using tetrahedral 3d lut interpretation in Davinci Resolve already.)

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Interesting; what comes to mind is that the latest files allow projection below zero. This only happens in theoretical space (i.e. below legal LogC / VLog), and projects sans clipping (an offset immediately after can bring sub-zero data into view).  This area shouldn't be encountered in real footage, so it may be the higher Isos which change the lower data range (S1a is optimized for VLog 640 Iso, 100 Cine-D, 400 HLG). Also, luma grade maneuvers in advance of the Pre/conversion is another way to bring this range into view.  I used to have an artificial rolloff to 0 black for theoretical black projection, but this caused problems downstream, so I removed that cap with the latest files. For noise, increased color separation will amplify noise, despite completely smooth tetra interpolation, if the footage has noise macroblocks. Higher bitrate codecs and lower Iso is optimal for clean imaging. Can you send me .tifs of the raw footage to noodle around with?

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  • 2 months later...
On 3/13/2021 at 11:15 PM, TomTheDP said:

@Sage

Should the luts work just as well for Prores Raw on the S5 and A7S3?

From what I've seen, ProRes Raw is slightly different. I'm planning to get a newer Raw recorder to see if a Pre is warranted, but I think it is usable.

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  • 2 weeks later...

I was so satisfied with EmotiveColor for my GH5 that I purchased it again after switching to a X-T4 but I got a dumb question for @Sage:

For the GH5, there was a PRE for levels when transcoding VLOG-L in H.264 to ProRes. Is that not necessary when transcoding the F-LOG H.265 to ProRes and using them in DaVinci Resolve?

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It's a good question; I don't recall there being the same flagging issue. I am in the midst of going back through all cameras for a new update, and I'll test this. The key is, does the LogC variant place black level at 8 Ire, or notably lower (should sit at 8 )

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  • 1 month later...

Emotive Color V5 'SPECTRUM'

The V5 'Spectrum' update is ready. The V5 emails are going out now (let me know if you haven't received it). It is the culmination of four years of engine development, and I hope you enjoy!

Emotive Color Component ('EC709')

  • EC709 component (Full/Theatrical) rebuilt with new engine, allowing accurate, uniform far gamut projection of Arri display table
  • Arri Rec.2020 now used as the color target (projected within EC709 envelope); results in deeper saturated red and blue that are otherwise clipped in Arri's Rec.709
  • High Scale is now Full Scale (unlabeled); a direct replacement for LogC+Rec709, with notable advantages (aesthetics and gamut preservation)
  • New Classic 'Soft' and 'Hype' variations (like V3-era 'Soft' and 'Main')
  • Refined natural saturation model

Core LogC

  • Fully realized uniform far gamut projection from known lower saturation samples (solves issue that caused saturated orange to twist towards red)
  • New rolloff math; allows grayscale reconciliation of high saturation brightness values (only available for interpolated .cubes; not achievable in Matrix)
  • Added final, fourth calculation pass (post-smoothing), which allows absolute accuracy to known sample points in final render (while retaining smoothness)
  • Corrected an issue that allowed smoothing algorithm to clash with a 'safety lock' on grayscale hue, that could result in red-green banding near the grayscale (especially with 33x under Trilinear Interpolation); now fully smooth regardless of grayscale

Misc.

  • New Ceiling Modifier [POST] files; allows variable highlight compression
  • New 'Natural' profile [PRE] for GH5 (shares settings with Cine-D: -5 Sat, 200 Iso)
  • Remade all PREs (picture profiles / exposures)
  • Revised Pdf; Important: DaVinci Resolve - Enable 'Tetrahedral Interpolation' under Project Settings > Color Management > Lookup Tables   (allows 65x performance with 33x cubes; complete gradient smoothness - FCPX has this as default)
    • Remade Premiere PREs with new measurements (to reflect 2021 Premiere's improved codec color); no 8-bit VLog or Cine-D PREs needed
    • Significant revision to Premiere Pdf guide; Advanced layering section is no longer relevant, use Lumetri's luma curve (improved significantly)
    • Gradient Test is now 16-bit png (compatible with Premiere) rather than tif
  • Entire Matrix PowerGrade now printed directly from the engine (complete reverse-engineering of .drx format):
    • Precise values entered directly into the curve interfaces, at maximal point density
    • Improved engine gamma accuracy enables significantly improved base matrices
    • New LogC Exposures feature (true exposure gammas extracted from sample data)
    • New 4200K PowerGrade variant

If you have any videos or stills you've made that you can share, I'd love to see them!

-Alex

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@Sage I'm still absolutely loving this LUT, and it just keeps getting better and better! 

I use it for pretty much every single project I shoot, S1 for A-cam and GH5 for b-cam, but lately, combined with anamorphic and pro res raw, it has felt extra tasty. I just love what it does to greens, especially. These screenshots are some standouts from the past couple weeks. Thanks for all your hard work! I recommend your Alexa LUT to all my lumix-shooting friends 👌🏻

I Am Sandy - Faith Pitts Blood Drive .jpg

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Redo_1.jpg

Redo_7.jpg

Broll_1.jpg

Broll_6.jpg

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3 hours ago, Sage said:

Really nice Parker. What anamorphics do you use? I'm now working on a software that will integrate all steps (WB, Exp, ABL etc) to vastly simplify the workflow (and make other things possible)

Thanks Sage! What I do to simplify the workflow in FCP is to add the full stack of pre and post LUTs that I need, make sure they're all in the proper order just once, and then I simply save the whole thing as a custom effects preset, so that I can just drop my single "S1 Alexa 24p" effect onto a clip and it's 95% of the way there. Definitely makes it much easier to use, and I've also been able to share this effects preset file with my assistant editors when they're handling my footage, so that I don't even have to try and explain the order or have to make them read your explainer pdf. 

As for the anamorphics, all of the shots I shared above were with the aivascope 1.5x (amber flare version) and contax zeiss taking lenses.

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14 minutes ago, Parker said:

Thanks Sage! What I do to simplify the workflow in FCP is to add the full stack of pre and post LUTs that I need, make sure they're all in the proper order just once, and then I simply save the whole thing as a custom effects preset, so that I can just drop my single "S1 Alexa 24p" effect onto a clip and it's 95% of the way there. Definitely makes it much easier to use, and I've also been able to share this effects preset file with my assistant editors when they're handling my footage, so that I don't even have to try and explain the order or have to make them read your explainer pdf. 

As for the anamorphics, all of the shots I shared above were with the aivascope 1.5x (amber flare version) and contax zeiss taking lenses.

That's a good idea. The Pdf can be a lot to take in for the uninitiated 🙂 With anamorphic, I've wanted to experiment with that for a long time, but have stayed spherical for the time being. I think there are some good complete m4/3 anamorphics now that aren't too expensive (relative to most).

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Darn, @Parker, you nailed it! Shots are all from the S1 or some from the GH5? S1 or S1H?:) I was close to purchases Sage piece of art. But then figured I will do it for a S1 only job! Last one was FS700 plus 10percent S1 in the mix. Cannot wait to do a S1 only gig, once I got my rigging set!:) cheers

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