Ah, sorry, now I got what your'e looking for. What about something like this:
fromRec709((x-64/1023)/((940-64)/1023)) The function itself is obvious, and what I did inside is first subtract the offseted black (64/1023) and then normalize this new curve (which now is going through the 0/0 point) by the offseted whitepoint, which is (940-64)/1023. Hope this is correct, it's a little bit late to do such theoretical things :) Abraham Am 30.10.2012 um 19:21 schrieb Francois Lord: > Yes, that's the east way of doing it. > But what I want is the artist-friendliest way of doing it. And that would be > to choose a colorspace directly from the read and write nodes. And I also > want that LUT to be expressed as a formula, not as a list of value pairs. > I'm working on it. > > Thanks. > > On 30/10/2012 13:56, Schneider, Abraham wrote: >> sorry, mixed up the values: >> >> whitepoint has to be 64/1023 (or 16/255) >> blackpoint was correct: 940/1023 (or 235/255) >> >> Abraham >> >> >> Am 30.10.2012 um 18:47 schrieb Schneider, Abraham: >> >> > Should be a two-step/node solution: >> > >> > - import it with colorspace set to linear (to avoid any conversion) >> > - add a Grade node, set the blackpoint to 16/1023 and whitepoint to >> > 940/1023 (this expands the limited range to full range) >> > - add a colorspace with 'in' set to 'rec709' and 'out' set to 'linear' >> > (removes the rec709 gamma) >> > >> > if you want to put this into LUT, use the CMSTestPattern, apply the nodes >> > above and export a LUT with the GenerateLUT node. >> > >> > Abraham >> > >> > >> > Am 30.10.2012 um 15:55 schrieb Francois Lord: >> > >> >> Hi. >> >> >> >> Does anyone has a formula for a LUT in Nuke to convert REC709 limited >> >> range to linear? I know I can sample a ramp and create a curve, but I >> >> would prefer a formula. >> >> >> >> Thanks. >> >> >> >> Francois. >> >> >> > >> > Abraham Schneider >> > Head of VFX pipeline / VFX Supervisor >> > >> > >> > ARRI Film & TV Services GmbH >> > Tuerkenstr. 89 >> > D-80799 Muenchen / Germany >> > >> > Phone +49 89 3809-1269 >> > >> > EMail [email protected] >> > www.arri.de/filmtv >> > _______________________________________________ >> >> Nuke-users mailing list >> >> [email protected], http://forums.thefoundry.co.uk/ >> >> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >> > >> > ________________________________ >> > >> > >> > ARRI Film & TV Services GmbH >> > Sitz: München Registergericht: Amtsgericht München >> > Handelsregisternummer: HRB 69396 >> > Geschäftsführer: Franz Kraus, Dr. Martin Prillmann, Josef Reidinger >> > _______________________________________________ >> > 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 >> > > _______________________________________________ > 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
