GH5 to Alexa Conversion

[Sage]

18 minutes ago, tihon84 said:

Did you shoot this examples using 8 bit codec? A see many blocking and color artefacts. 

Any 10 bit examples?

But colors and contrast are amazing. 

Yes, every shot in E2 is 8 bit. Many are 1080p 120fps, and many are underexposed. I'd like to do something more technically rigorous soon

Here is a 10 bit example, with original V-Log, and GHa Tungsten main conversion:

[Sage]

Here is a gif comparison of the unaltered GHa Tungsten Main conversion, and original V-Log color with matched contrast and saturation:

 

[Sage]

People have been asking to have an example of the Alexa conversion on HLG footage, and want to know if it is as good as VLog

It is a precision match; I finally got around to shooting a comparison, and here are the stills.

HLG, HLG with GHa Tungsten Main (no further alteration), VLog, and VLog with GHa Tungsten Main (no further alteration)

Also, something interesting and useful coming soon.

 

[majoraxis]

@ SAGE - Looks great!  I think I might prefer the HLG GHa Tungsten Main version as compared to the VLOG GHa Tungsten Main version.  Seems like there is a slight bit more gradation information than with the VLOG render in the highlights and the shadows.  I think this is a limitation of VLOG rather than your LUT.  Really looking forward to what you come up with next!

[Sage]

1 hour ago, majoraxis said:

@ SAGE - Looks great!  I think I might prefer the HLG GHa Tungsten Main version as compared to the VLOG GHa Tungsten Main version.  Seems like there is a slight bit more gradation information than with the VLOG render in the highlights and the shadows.  I think this is a limitation of VLOG rather than your LUT.  Really looking forward to what you come up with next!

Thanks @majoraxis;

There are slight differences between the conversions (more so with Tungsten). Nothing significant, but it is likely the reason for any visual disparity

[seku]

Hi Sage,

just a silly comprehension question ... why are there 2 LUTs? let's say i whitebalanced my shots with graycards, why does it still matter if i use the tungsten or skylight LUT?

i feel like i don't understand something quite important here.

[Sage]

42 minutes ago, seku said:

Hi Sage,

just a silly comprehension question ... why are there 2 LUTs? let's say i whitebalanced my shots with graycards, why does it still matter if i use the tungsten or skylight LUT?

i feel like i don't understand something quite important here.

Sure; the essential reason for this is to achieve a more accurate (and visually pleasing) conversion for the given light source.

Here is a longer description I wrote on Dvxuser:

"There are two things which combine to result in a color science output; these are the sensor response and the interaction between white balance and color space. In the case of sensor response, this is the wavelengths of light that the RGB photosite dyes allow in to constitute red, green, and blue, and how the pipeline interprets and sums this base signal. Because of this, different sensors will 'see' different results in the same light source. While daylight and tungsten are highly predictable, leds and flourescents are highly variable in their exact wavelength distribution. For a fully accurate conversion, one must be made for each distinct light source. Each new conversion is work intensive. In the case of white balance interacting with color space, each profile - and each white balance of that profile - will differ in the same camera with the same light source. All of these moving parts constitute a fully complex system with a predictable result given fixed conditions. I am working on ideas to tackle this (a conversion for each fluorescent tube, each led dial setting, etc. would not be practical)."

Perhaps I will make examples of how each light source looks processed with both conversions, so that you can decide what works best for you.

[Sage]

@seku

Here you are:

[IshootbeforeItalk]

On ‎30‎-‎11‎-‎2017 at 9:50 PM, Sage said:

"GH5 V-Log and Hybid Log-Gamma are transformed to precisely match the color science of the Alexa, without compromise."

"The GH Alex conversion completely transforms the GH5 image, addressing every nuance of color reproduction (from shadows to highlights, low saturation to high saturation, for every possible hue). This includes an organic rolloff which fully eliminates channel clipping."

EmotiveColor.com

PDF

YouTube

I found that any flat Alexa LUT works quite well on V-log. 

[Sage]

8 minutes ago, IshootbeforeItalk said:

I found that any flat Alexa LUT works quite well on V-log. 

"As detailed in the PDF, the conversion is not simply a shift in known format parameters. You can use LutCalc or buy Lattice to create a tailored V-Log to LogC conversion, which will give you more 'Alexa-like' colors. I know this, because indeed I bought Lattice in my dogged pursuit of getting something more Alexa-like. But as you have likely noticed, the result is far from an accurate match to an Alexa. I made this first and foremost for myself, because I really wanted a true conversion"

[Wild Ranger]

On 7/12/2017 at 10:45 PM, Sage said:

People have been asking to have an example of the Alexa conversion on HLG footage, and want to know if it is as good as VLog

It is a precision match; I finally got around to shooting a comparison, and here are the stills.

HLG, HLG with GHa Tungsten Main (no further alteration), VLog, and VLog with GHa Tungsten Main (no further alteration)

Also, something interesting and useful coming soon.

 

So this mean that i can have the same result using HLG instead of Vlog? (I don't own vlog) 

[seku]

thanks for the comparison between daylight and tungsten. very educative

[Sage]

5 minutes ago, Wild Ranger said:

So this mean that i can have the same result using HLG instead of Vlog? (I don't own vlog) 

Yes; they are effectively identical.

The main advantages of V-Log are the 8-bit modes, and in-camera .Vlt monitoring.

2 minutes ago, seku said:

thanks for the comparison between daylight and tungsten. very educative

No problem

[tihon84]

Hi! In emotion || you get quite deep colors and contrast image. What additional adjustments (over GHA main) did you do to  achieve this image? And do you think it`s possible to use an ISO 1600 on gh5?

Thank you

 

P.S.: if i`ll buy your LUTS will you provide any updates for free? You mentioned that something new is coming...

[Sage]

1 hour ago, tihon84 said:

Hi! In emotion || you get quite deep colors and contrast image. What additional adjustments (over GHA main) did you do to  achieve this image? And do you think it`s possible to use an ISO 1600 on gh5?

Thank you

 

P.S.: if i`ll buy your LUTS will you provide any updates for free? You mentioned that something new is coming...

Speaking for myself, I never leave ISO 400. But ISO 1600 on the GH5 is quite good.Even ISO 3200 works in a pinch. I'd recommend good primes, and good lights.

Updates are always free. There have been four updates since release, and should I make any further refinements you will receive an email from me - though I am quite pleased with where it is now. That something new is separate from GHa, though you will have it with GHa.

All that's needed to replicate E2 are the lift/gamma/gain sliders (attached). I dropped lift to the point that shadows were dark (but not black), and raised gain somewhat (not too extreme). And then I tweaked gamma to make sure midtones were optimally placed. Further finesse to luma may be made with the luma curve, but for the most part it was all added contrast via lift/gamma/gain. No alteration was made to saturation (though GHa saturation has been refined since then), and occasionally I may have shifted midtones to be warmer with the color wheels (for the most part kept neutral, with no color casts). The 'Soft' conversion should be used for color cast grading.

I am considering adding a page to the PDF to elaborate on grading GHa. In summary, GHa luma is placed on the IRE scale for a shot that uses the full dynamic range (for non-destructive, non range-preferential, grade-ready preparation). In all cases, but especially If a shot has a narrower range - and most do - luma should be dialed in with Lift/Gamma/Gain (and/or curves) to adhere to cinema IRE placement for a finished grade (drop the shadows - see attached).

[tihon84]

Thanks!

Is it ok with LOGC.cube (daylight)?  I thought it would be less contrasted. Or its ok?

 

[Sage]

1 hour ago, tihon84 said:

Thanks!

Is it ok with LOGC.cube (daylight)?  I thought it would be less contrasted. Or its ok?

 

Yes, that's correct. Relative to V-Log, the apparent exposure is lower (shadows and midtones will get darker).

I do recommend Main and Soft, as they have a special sat recipe that Arri's Rec709 is known for, but the result is superior to their 709, in my opinion.

[Linus N]

Hey!

I bought these and just briefly popped them on some footage I'm working with atm, liking the results in most cases. I plan on taking some time to test this out in a controlled environment, what are people interested in seeing? Taking requests with no guarantee they will be fulfilled

@Sage a tiny feedback; in the e-mail I received two days ago with the updated versions, the names of the .cube's were different than those files they are meant to replace. Got me confused there for a bit and had me looking through each folder four times like "where dem files at?!"

[Sage]

Thank you @Linus N, I appreciate it. The structuring of the GHa file set has changed going forward (Hlg [PRE]), and I hadn't considered it

Please, share your work! I am excited to see it

[tihon84]

5 hours ago, Linus N said:

Hey!

I bought these and just briefly popped them on some footage I'm working with atm, liking the results in most cases. I plan on taking some time to test this out in a controlled environment, what are people interested in seeing? Taking requests with no guarantee they will be fulfilled

@Sage a tiny feedback; in the e-mail I received two days ago with the updated versions, the names of the .cube's were different than those files they are meant to replace. Got me confused there for a bit and had me looking through each folder four times like "where dem files at?!"

What NLE do you use? BE careful: AE 2015 do something with luminance, as result, you got more contrasted input image... AE 2017+ seems to be ok with that.

Sage,  you did a really good work in my opinion. PDF  is very helpful too.