@shian Have you shot or played around with any varicam footage for comparison? If you want I can shoot some fast 10 bit gh4 test footage files this week and send them your way..

Alexa C is nice, it controls the banding and limits highlights pretty well, but skews green - CG Pro EASY creates a very similar interpretation without the green skew and an ever so slightly higher gamma curve.

Here are Alexa C vs. EASY vs LIMIT

for easier tabbed viewing comparison go to the end of the roll https://www.flickr.com/gp/76276262@N04/1DQ128

@jopereira no, not only in the timeline, also an H264 render out of Premiere Pro gives very ugly banding, as I said even with BMPCC 10 bit footage. Whereas in e.g. Resolve everything is fine. Hence it could be that Premiere pro is part of the problem. The same happens with Edius Neo 2.5, as it is also 8bit based - you obviously need much more bit depth (e.g. 32bit) if you push around an 8 or 10bit file to safely map it to a final 8 bit space for output.

@Faudel meaning the Arri Log C curve is perfect for GH4 V Log in 10 bit?

You have to change your setting in PP to work in 32bit, and you have to render out in a 444 format to not lose that information

http://blogs.adobe.com/VideoRoad/2010/06/understanding_color_processing.html

Is Alexa C-log LUT freely available for download?

If so, where?

@shian good remark and and thanks for the link, I was not aware to always check the "Maximum Bit depth" checkbox in the sequence settings as I never did heavy image manipulations in the past. I thought that the sequence would adjust to the input material automatically. When I started to use the BMPCC flat files and tried to push it in PPro I could immediately see that something is wrong (heavy banding). Thats why I used DV Resolve from there onwards.

Good to know ;-), and probably some of the users reporting banding here should be aware of this as well!

There is a free online software where you can look at the different curvs in comparison to each other. https://cameramanben.github.io/LUTCalc/LUTCalc/index.html

Choose v-log for input ja and output what you prefer. This software will create a translation lut for from different color space (from gamma to gamma and from gamut to gamut) to each other. The online version works only in 8 bit, but the desktop (3 dollars) works in 10 bit (only for mac sorry).

V-Log is a variation of video gamma. -Gamma is the curv that shows how real life luminance values are translated to luminance values in the 0-256 (in 8bit) and 0-1024 (in 10bit)

GH4's color in V-log is (most probably) translated to Panasonic V-gamut color space, not to rec709. -sRGB, AdobeRGB, Prophoto, CMYK are all gamuts (color spaces), And so is Panasonic V-gamut as well.

I'm no colorist, but after reading and thinking a lot about this topic I think the banding/macroblocking issue might be caused by the lack of translation from Panasonic V-gamut to rec709 gamut when you just use curves or even Luminance (Gamma) correcting luts. I'll test this hypothesis later and post some test clips here.

So when you open a v-log video in premier or any other editor and the software automatically translates the color info to sRGB or Rec709 you will get issues.

I'll test opening the footage in 32bit mode and applying gamut to gamut and gamma to gamma LUT to the footage it might fix the issues.

I'll share the LUT's here if I get them to work.

By the way if you google different terms people use you will learn a lot (Wikipedia is great in this regard).

This one is good: https://en.wikipedia.org/wiki/Color_space

@aaronchicago ...and for us using FCPX ...can we still use Alexa LUT ?

@aaronchicago @labalbi , yes this means that arri lut should work for Panny V-Log , should work for sony S-log3 too , lol they all stick to arri log !

^^ Agree, Panasonic needs some pressure on this. The V-Log lut is just skewing green for me in Vegas, though I do really like the highlight roll-off I'm seeing. The vibrant chroma noise apparent after further pushing the image is a bit of a mystery, never seen anything like it before.

@jopereira It might be that the lut you are using doesn't re-map the gamut, it might only re-map gamma. I'll conduct some test too later when I have time.

Gamma and Gamut are two different things and its complicated to understand what they are.

@Xenocide38 We might benefit from understanding what is the difference between color noise and macro blocking. I don't quite understand it my self. All cameras have color noise under a sensor specific IRE threshold just like luminance noise. I might conduct some tests later to determine what is the threshold for GH4 and V-log.