Do you have access to the original Arriraws? If so, you could try to debayer 
them again in the Arriraw converter with a different setting (reducing 
sharpness to 0, for example).

Here is where you can get the converter from:

http://www.arri.com/camera/digital_cameras/tools/arriraw_converter.html


On Jun 29, 2012, at 10:26 AM, Aélis Héraud wrote:

> -- Okay, I had some trouble sending this mail last night so I hope you'll 
> receive it now. Sorry for duplicates copies. --
> 
> Hi folks, I'd like to ask you something.
> 
> We have to deal with some greenscreens in Alexa and I know some people have 
> had some trouble with it. Overall the greenscreens are pretty good and we're 
> able to get a good result, but we noticed something on the data and I'd like 
> to have your say on this matter.
> 
> We noticed some artefacts in the Red and Blue channels, especially on the 
> thinner blond hairs.
> The plates are in 2880x1620, it was recorded in ArriRaw (via T-Link) and then 
> converted in DPX (Colorspace AlexaV3LogC) so it's pretty much the best 
> quality we can have, there's no compression.
> 
> <Mail Attachment.png>
> 
> As you can see the RGB seems pretty much ok and the green channel is good, 
> but the red one has some pixels in staircase and I won't even talk about the 
> blue one. The last picture is a first key.
> 
> After some investigations we're pretty sure it has something to do with the 
> debayering process. It's maybe due to the algorithm, the interpolation 
> between pixels isn't very good in the red and blue channel. I don't know 
> exactly but that's the only explanation we could come up with so far.
> 
> My question is : Is there a way to fix it in Nuke without altering the data 
> (the good one) or are we stuck with that ? Any idea ?
> 
> I tried to split the channels and to put a blur at 1 on the Red one and it 
> seemed to help a bit at first but eventually we can feel the softness and we 
> lose the thinner hairs, which I'd like to avoid. I'd keep that as my last 
> option.
> 
> Our other option would be to ask the company who did the debayering but I'd 
> like to find another way.
> 
> Thanks for the help
> 
> Aelis
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