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Sage

GH5 to Alexa Conversion

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hi. V1 vas close to alexa in case of colors and provided references. As i can see now there are some color differens between new and old luts. So... do you try to create more correct alexa colors or what?)

 

for me the main idea is to create the transformation lut for gh5 vlog to achieve alexa c-log colors and dr as close as possible. Following instructions to shoot with the same wb and exposure

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EOSHD Pro Color for Sony cameras EOSHD Pro LOG for Sony CamerasEOSHD C-LOG and Film Profiles for All Canon DSLRs

@tihon84 V1, especially Daylight, is not bad. V1 Day with VLog in Resolve is quite good. Notably, the Emotive Color component is quite different in exposure handling (which is apart from LogC accuracy). Emotion II is especially egregious, because it features pre-release GHa (pre-Blue and other updates), and the original 8bit PRE, with a hasty midnight grade. I knew (and noted then) that it was a poor technical showcase, but something that I wanted to make for some time

That being said, V1 did have an important flaw (apart from the limitations of that process). That flaw was related to the fact that I did not own the Alexa, and had a single window to get the measurements right. I opted to use different lenses, which I thought would be sufficiently neutral. I didn't get a PL adapter for the GH5, and only realized that this would be a problem upon reviewing the results of the shoot. It turned out that Zeiss CP.2s are quite poor in color rendition, but my Sigma 18-35 was excellent. So, I neutralized the grayscale white balance... a kind of continuous white balance shift throughout the grayscale, to accommodate the difference

Subsequently, I bought an Alexa (really), to make it perfect. This has proved vital, because I have redone the measurements countless times now, tweaking and tweaking again (same lenses all the way). V2 is approaching the theoretical 'perfect conversion' because of this, and because of the new process, which features 25 times the number of samples, and the code I wrote to handle that unwieldy sample count to a new standard of accuracy and smoothness (previously out of reach with the given degree of intricate transform)

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6 hours ago, Sage said:

@tihon84 V1, especially Daylight, is not bad. V1 Day with VLog in Resolve is quite good. Notably, the Emotive Color component is quite different in exposure handling (which is apart from LogC accuracy). Emotion II is especially egregious, because it features pre-release GHa (pre-Blue and other updates), and the original 8bit PRE, with a hasty midnight grade. I knew (and noted then) that it was a poor technical showcase, but something that I wanted to make for some time

That being said, V1 did have an important flaw (apart from the limitations of that process). That flaw was related to the fact that I did not own the Alexa, and had a single window to get the measurements right. I opted to use different lenses, which I thought would be sufficiently neutral. I didn't get a PL adapter for the GH5, and only realized that this would be a problem upon reviewing the results of the shoot. It turned out that Zeiss CP.2s are quite poor in color rendition, but my Sigma 18-35 was excellent. So, I neutralized the grayscale white balance... a kind of continuous white balance shift throughout the grayscale, to accommodate the difference

Subsequently, I bought an Alexa (really), to make it perfect. This has proved vital, because I have redone the measurements countless times now, tweaking and tweaking again (same lenses all the way). V2 is approaching the theoretical 'perfect conversion' because of this, and because of the new process, which features 25 times the number of samples, and the code I wrote to handle that unwieldy sample count to a new standard of accuracy and smoothness (previously out of reach with the given degree of intricate transform)

Wow! Now i see.

Thank you. Great work! 

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8 hours ago, Sage said:

@tihon84 V1, especially Daylight, is not bad. V1 Day with VLog in Resolve is quite good. Notably, the Emotive Color component is quite different in exposure handling (which is apart from LogC accuracy). Emotion II is especially egregious, because it features pre-release GHa (pre-Blue and other updates), and the original 8bit PRE, with a hasty midnight grade. I knew (and noted then) that it was a poor technical showcase, but something that I wanted to make for some time

That being said, V1 did have an important flaw (apart from the limitations of that process). That flaw was related to the fact that I did not own the Alexa, and had a single window to get the measurements right. I opted to use different lenses, which I thought would be sufficiently neutral. I didn't get a PL adapter for the GH5, and only realized that this would be a problem upon reviewing the results of the shoot. It turned out that Zeiss CP.2s are quite poor in color rendition, but my Sigma 18-35 was excellent. So, I neutralized the grayscale white balance... a kind of continuous white balance shift throughout the grayscale, to accommodate the difference

Subsequently, I bought an Alexa (really), to make it perfect. This has proved vital, because I have redone the measurements countless times now, tweaking and tweaking again (same lenses all the way). V2 is approaching the theoretical 'perfect conversion' because of this, and because of the new process, which features 25 times the number of samples, and the code I wrote to handle that unwieldy sample count to a new standard of accuracy and smoothness (previously out of reach with the given degree of intricate transform)

I purchased the first version and I've used it often.

Is this a free or paid update? 

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Hi, can you tell me  more about how to set WB, please...

What do you usually use as a white paper? Grey Card?

I have a really different results when i set wb using white paper, grey card and manually choosing 5600 on the daylight... 

And manual settings  wb in Kelvins working MORE accurate for me...

Thank you

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@tihon84 Using a gray card is ideal. You'll want the gray card to reflect the key light

Lenses with non-neutral grayscales will essentially 'shift' balance slightly throughout the grayscale. This is to be expected; its part of the 'character' of the lens

A gray card will avoid complications of a white paper (tint/transparency). When it comes to minor adjustments of white balance, using the post WB tools (eyedropper/tint/temp) works very well (Its ideal to make sure that white balance is generally correct on set)

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"I am pleased to announce GHa V2, the reference grade update. For the last six months (since original release), I have been building a new version of the conversion from the ground up, to achieve a new standard of precision and smoothness (silk gradients).

The changes in V2:
- 25x the Number of Color Samples (25k Per Camera)
- Custom Coded C++ Color Engine (Smooth Interpolation)
- Alexa On Hand (For Repeated Iteration)
- Corrected Lens Distortion of Original Conversion
- Smarter Handling of of Exposure Placement to Maximize DR (both Emotive Color and LogC)
- Cine-D Support (and Improved [PRE]s)
- Premiere Pro Specific [PRE]s (for VLog & Others)
- Improved Documentation"

Here is the new PDF

Emotion II (Updated to V2)
(Edge/Explorer or Safari recommended for most accurate color; Chrome/Opera Ok; Avoid Firefox)

day.thumb.png.c947048debc775809b7e4deb18bfac63.png

tun.thumb.png.db08b1fa1007b4f2eb18b7cc6cdc832a.png

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26 minutes ago, Sage said:

"I am pleased to announce GHa V2, the reference grade update. For the last six months (since original release), I have been building a new version of the conversion from the ground up, to achieve a new standard of precision and smoothness (silk gradients).

The changes in V2:
- 25x the Number of Color Samples (25k Per Camera)
- Custom Coded C++ Color Engine (Smooth Interpolation)
- Alexa On Hand (For Repeated Iteration)
- Corrected Lens Distortion of Original Conversion
- Smarter Handling of of Exposure Placement to Maximize DR (both Emotive Color and LogC)
- Cine-D Support (and Improved [PRE]s)
- Premiere Pro Specific [PRE]s (for VLog & Others)
- Improved Documentation"

Here is the new PDF

Emotion II (Updated to V2)
(Edge/Explorer or Safari recommended for most accurate color; Chrome/Opera Ok; Avoid Firefox)

day.thumb.png.c947048debc775809b7e4deb18bfac63.png

tun.thumb.png.db08b1fa1007b4f2eb18b7cc6cdc832a.png

Great work man!
Can't wait to try out the Cine D conversion. Was avoiding 60p for many reasons until now (1080p60 10 bit is oversharpened, UHD60p 8 bit in V-Log is almost as messy as GH4 8 Bit V-log was...)

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1 hour ago, deezid said:

Great work man!
Can't wait to try out the Cine D conversion. Was avoiding 60p for many reasons until now (1080p60 10 bit is oversharpened, UHD60p 8 bit in V-Log is almost as messy as GH4 8 Bit V-log was...)

Thanks deezid! The stars of the show are the main conversions, which are really, really accurate (and smooth). Huge leap for Tungsten.

Luma for Daylight is placed very differently; it will result in a lot more effective highlight range when exposed for V2.

1 hour ago, tihon84 said:

Thank you for V2 version!

did you shoot this sample :"GHa Daylight Sample 8.jpg" in CINE-d profile?

Doesn`t look like a VLOG

Thanks tihon84; its just good ole' V-Log (and only Daylight Main V2 applied). The scene was very striking, with late day sun pouring into the little yellow room, overlooking the sea.

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44 minutes ago, dxotic said:

Hi Sage,

where can I get the latest download from? Looking to testing it out on the other shots I have from V1!

Hey dxotic, you should have an email from me

Exposure placement for Day V2 is quite different; this is how I described it to David L'Abbée:

"Before, clean range was being rolled off into the noise floor with Daylight; this wasn't very smart. Now, range is allotted to the highlights, which allows more meaningful DR when exposed for V2. For V1 footage, you can place the luma per page 8, and slightly increase saturation to compensate"

18 minutes ago, mercer said:

Sorry, but you bought an Alexa so you could make your GH5 look more like the Alexa?

Why not just use the Alexa?

Hehe, because I'm crazy! ;) I got it to make this conversion perfect, because that was a much better proposition than trying to measure it on borrowed time (which is basically what limited the fidelity of V1). I did upwards of twenty measurement redo's for V2, all told. tweaking the approach along the way. This was critical, as the first V2 run through was really far off of what was needed for the code to ingest

Also, it is the most unwieldy thing. Its got minimal kit needed to run (no battery, Frankenstein hdmi monitor, etc.); its a heavy computer with wires, in 2k. The GH5 with IBIS allows me to shoot in my particular style, which is all about motion

Also, per my promise to you a few months ago, here are the raw side-by-sides:
Daylight Alexa & GH5 Raw Footage
Tungsten Alexa & GH5 Raw Footage
(Use DaVinci Resolve for these - accurate Arri ProRes)

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3 hours ago, JeremyDulac said:

Great stuff, Alex! As i am working my way through testing I am wondering - Are the 'PRE' files good enough now that using HLG is just as good as VLog straight out of camera?

Thanks Jeremy!

On their own, as a conversion to VLog, they are really accurate. Looking at the point cloud throughout the color space, they're near perfect.

But it is my impression that Vlog is superior for locking in skintone nuances and absolute smoothness. This is essentially because combining two really intricate conversions magnifies translation error. This doesn't apply to the simpler PREs (i.e. Premiere 10bit VLog and ProRes), because of their uniformity.

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