Hey Lucien Agreed - theres something weird done to the plates that I’m unable to solve my end.
I can reverse out everything neatly the way i have it - but its messy and i don’t want to cause problems down the road - I’ve settled to just using the standard colorspace node: in set to AlexaLogC - and out to Linear - Primaries untouched at sRGB setting Also using an add at top in log space to offset negatives. I’m not bothering with ACES - shame - mainly because if I use an OCIO colorspace node alone, with these plates, I have to offset ALOT before the negatives disappear - and I find it unusable to work with it like that - such as pushing skin tones 2 stops to high etc. Thanks for all the help and pointers i love working with ACES, but the plates have to be treated correctly :) N Neil Rögnvaldr Scholes Director | VFX Supervisor www.neilscholes.com <http://www.neilscholes.com/> +44 (0) 7977 456 197 > On 31 Oct 2016, at 16:44, Lucien Fostier <lucienfost...@gmail.com> wrote: > > Hey Neil, > > the result you get from this srgb -> arri wide gamut are not surprising but I > dont think they are appropriate in your case. > > If you are converting this plate with negative values from srgb to arri wide, > you are essentially saying that the code value of your image which are > negative coordinate in srgb gamut are likely to be positive in arri wide. > > That's the opposite direction of the transform that you found causing problem > in the first place( arri wide to aces cg). > > when you convert from a colorspace that gamut A and another with gamut B, if > gamut B is smaller than A then you may end up with negative values. > > Besides that, camera manufactor log encoding use a log operator. The log > operator for the 0 code value is equal to infinity so they always add a tiny > offset before feeding it to the log operator. > > How big this offset is depends on the camera manufactor requirement and > "look" intention. > > These requirements may be different than the vfx work needs. > > On top on that, you got noise that plays a part in this game. > > So in the end, I would get rid of this srgb to arri wide and adjust your > offset accordingly. > > Cheers > > Lucien_______________________________________________ > Nuke-users mailing list > Nuke-users@support.thefoundry.co.uk, http://forums.thefoundry.co.uk/ > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >
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