Don't overthink the Read's 'colorspace' conversion - it can only do a 1D lut applied to RGB equally. It's not a colorspace conversion per-se, only a gamma response conversion.
-jonathan On Dec 31, 2011, at 1:34 PM, Randy Little <[email protected]> wrote: > Ok I am calibrating a Camera and light meter. shooting a grey card ( > a good one that I know is 18%) I take this file red it into anything > that reads R3d. and in every case but nuke grey is .18xxxxxxx in float > and 127.xxxxxxx or 128.xxxxxx in 8 bit. huh. in nuke its .21% ok > weird. Make file in photoshop in sRGB 2.1 make middle grey 50% (cause > its gamma corrected sRGB) Take that tiff file into Nuke .21 AGAIN. > WHAT? ok set read node to RAW. MORE WHAT. It reads at .5 as I would > expect. ok I studied color a little. This sounds like color space > conversion matrix problem. Yup if you use LAB 50% then all is great. > But None of my files are LAB and in RGB they are fine. So it seems > nuke conversion going through LAB remapping RGB 50% to LAB 50% and > then not accounting for that. But also if I use a Gamma node set to > .402 I can get in a gradient .18 to be exactly the middle of the > gradient as well. This in tern doesn't distribute the values linearly > threw the gradient either at 10% translation I have only 7% > illumination change from dmax and from dmin 20% translation results in > 10% change. As expected when using a gamma node on a raw sRGB since > srgb is a power curve. Just nukes Power curve seems a bit off. > Is there a reason for this? > > > Randy S. Little > http://www.rslittle.com > _______________________________________________ > Nuke-users mailing list > [email protected], http://forums.thefoundry.co.uk/ > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users _______________________________________________ Nuke-users mailing list [email protected], http://forums.thefoundry.co.uk/ http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users
