I wondered how the screen would need to be calculated differently since the invert function might get you some crazy values in float space. It makes sense that they changed it to give us a visually accurate result when a mathematical one would look like an error.
On Wed, Jan 28, 2015 at 10:49 AM, John Mangia <j...@johnmangia.com> wrote: > Looks like the nuke screen algorithm has a low pass to allow for values > over 1 to comp more naturally. You can see the difference if you expose > down. > > On Wed, Jan 28, 2015 at 10:37 AM, Mads Lund <madshl...@gmail.com> wrote: > >> Ahh ok, so the "Screen" operation in the merge node does not just screen. >> >> Screen is the same as the Merge >> <http://help.thefoundry.co.uk/nuke/9.0/content/reference_guide/merge_nodes/merge.html> >> node, >> only with operation set to screen by default. It layers images together >> using the screen compositing algorithm: A+B-AB if A or B ≤1, otherwise >> max(A,B). In other words, If A or B is less than or equal to 1, the >> screen algorithm is used, otherwise max is chosen. Screen resembles plus. >> It can be useful for combining mattes and adding laser beams. >> >> However i still don't see why they don't apply this to the overlay method >> aswell. (why would you want clamp the image?) >> And it also doesnt explain why it clamps at 0 (since multiply does not >> clamp at 0) >> >> >> >> On Wed, Jan 28, 2015 at 2:46 PM, John Mangia <j...@johnmangia.com> wrote: >> >>> Screen is also a multiplicative operation, it's just inverted images >>> multiplied together and re-inverted. >>> >>> >>> On Wed, Jan 28, 2015 at 8:35 AM, Ron Ganbar <ron...@gmail.com> wrote: >>> >>>> The math used in Nuke for Screen makes it inheritingly clamp (it >>>> doesn't really clamp, but can not produce colors brighter than 1). >>>> >>>> >>>> >>>> Ron Ganbar >>>> email: ron...@gmail.com >>>> tel: +44 (0)7968 007 309 [UK] >>>> +972 (0)54 255 9765 [Israel] >>>> url: http://ronganbar.wordpress.com/ >>>> >>>> On Wed, Jan 28, 2015 at 2:15 PM, Mads Lund <madshl...@gmail.com> wrote: >>>> >>>>> According to the documentation: >>>>> >>>>> • overlay - Image A brightens image B. >>>>> Algorithm: multiply if B<.5, screen if B>.5 >>>>> >>>>> However Nuke also clamps the colors between 0 and 1. >>>>> It seem that all other compositing software does not clamp between 0 >>>>> and 1, so i am wondering if this is a bug in Nuke? >>>>> >>>>> >>>>> _______________________________________________ >>>>> 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 >>>>> >>>> >>>> >>>> _______________________________________________ >>>> 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 >>>> >>> >>> >>> >>> _______________________________________________ >>> 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 >>> >> >> >> _______________________________________________ >> 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 >> > > > > -- > John Mangia > > 908.616.1796 > j...@johnmangia.com > > _______________________________________________ > 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 > -- Daniel Short www.danisnotshort.com <http://www.vimeo.com/danisnotshort> 215.859.3220
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