I've never quite seen how anything that crosses channels, if there's any 
anti-aliasing involved, can not have issues...

If a red and a blue matte meet, and there is anti-aliasing along the edges, 
causing a pixel to be (0.5, 0.0, 0.5), how is that different to a similar pixel 
along an antialiased edge where a magenta matte meets black...

Hugh Macdonald
nvizible – VISUAL EFFECTS

[email protected]
+44(0) 207 659 2038
+44(0) 7773 764 708

www.nvizible.com

On 24 Mar 2011, at 23:08, Howard Jones wrote:

> in that case btw the red matte would be separate to the magenta, any overlap 
> would be black in the respective channels.
> 
> H
> 
> From: Howard Jones <[email protected]>
> To: Nuke user discussion <[email protected]>
> Sent: Thu, 24 March, 2011 22:45:32
> Subject: Re: [Nuke-users] Extract CMY Color id
> 
> should do...
> 
> splits into 
> primary (rgb outside of cmy bnw)
> secondary (cmy outside of rgb, bnw)
> tertiary (bw (split into bnw) outside of rgb, cmy)
> 
> H
> 
> 
> From: Deke Kincaid <[email protected]>
> To: Nuke user discussion <[email protected]>
> Sent: Thu, 24 March, 2011 22:33:12
> Subject: Re: [Nuke-users] Extract CMY Color id
> 
> This pulls perfect mattes even when you have a magenta and red matte
> on top of each other or any other primary/secondary overlapping?
> 
> -deke
> 
> On Thu, Mar 24, 2011 at 15:17, Howard Jones <[email protected]> wrote:
> > Hi
> >
> > <Shameless plug>
> > my secondary colour node on nukepedia/creative crash - splits any image into
> > rgb, cmy and bnw (black neutral whites).
> > The output will show you any set of above ie rgb, cmy, bnw mapped into the
> > rgb channels.
> >
> > So plug in your image choose cmy (as rgb) and in the rgb channels you will
> > have cyan magenta and yellow mapped to rgb respectively, so as long as its
> > pure cmy you get perfect mattes instantly
> >
> > </Shameless plug>
> >
> > Howard
> >
> >
> >
> > ________________________________
> > From: Spider <[email protected]>
> > To: Nuke user discussion <[email protected]>
> > Sent: Thu, 24 March, 2011 20:14:50
> > Subject: Re: [Nuke-users] Extract CMY Color id
> >
> > Merci Julien,
> > I'll try this at home in few minutes.
> > Maybe my 3d gay, sorry i mean guy like pink ;)
> > Spider
> >
> >
> >
> > 2011/3/24 Julien Chandelle <[email protected]>
> >>
> >> I just did this gizmo, you can pick any color choose if you want extract a
> >> matte or apply the alpha on your picture with a premult if you want. Of
> >> course I agree with Deke this way suck, an exr with matte is better but I
> >> prefer several RGB matte pass.
> >>
> >> set cut_paste_input [stack 0]
> >> version 6.2 v2
> >> push $cut_paste_input
> >> Group {
> >>  name Select_color
> >>  selected true
> >>  xpos -168
> >>  ypos 2
> >>  addUserKnob {20 User}
> >>  addUserKnob {41 color T Constant1.color}
> >>  addUserKnob {6 out_alpha l "Out Alpha" +STARTLINE}
> >>  addUserKnob {6 premult +STARTLINE}
> >> }
> >>  Constant {
> >>   inputs 0
> >>   channels rgb
> >>   color {0.3005436957 0.02121900581 0.3762620389 1}
> >>   last 100000
> >>   name Constant1
> >>   xpos 38
> >>   ypos 109
> >>  }
> >>  Input {
> >>   inputs 0
> >>   selected true
> >>   xpos -101
> >>   ypos 86
> >>  }
> >>  Difference {
> >>   inputs 2
> >>   gain 90
> >>   name Difference1
> >>   xpos -101
> >>   ypos 126
> >>  }
> >>  Invert {
> >>   channels alpha
> >>   name Invert1
> >>   xpos -101
> >>   ypos 171
> >>  }
> >>  Premult {
> >>   name Premult1
> >>   xpos -101
> >>   ypos 209
> >>   disable {{!parent.premult i}}
> >>  }
> >>  Shuffle {
> >>   red alpha
> >>   green alpha
> >>   blue alpha
> >>   name Shuffle1
> >>   xpos -101
> >>   ypos 235
> >>   disable {{!parent.out_alpha i}}
> >>  }
> >>  Output {
> >>   name Output1
> >>   xpos -101
> >>   ypos 287
> >>  }
> >> end_group
> >>
> >>
> >> On Thu, Mar 24, 2011 at 8:57 PM, Deke Kincaid <[email protected]>
> >> wrote:
> >>>
> >>> Keyer is pretty much it.  There are gizmos which just automate doing
> >>> id channels on nukepedia and creativecrash but underneath they are all
> >>> just keyers.
> >>>
> >>> For future though, get your cg guys to render multiple mattes to a
> >>> single exr instead of using id's which just suck, especially pink that
> >>> it likes to throw in there.  There are mel scripts for Mental Ray and
> >>> Vray which automate doing this.
> >>>
> >>> -deke
> >>>
> >>> On Thu, Mar 24, 2011 at 12:50, Spider <[email protected]> wrote:
> >>> > Hi everyone,
> >>> > I have a question maybe already ask (i checked before)
> >>> > i'd like to know what is the best way to extract CMY to make a object
> >>> > matte,
> >>> > i guess that their is a better way than use keying nodes.
> >>> > May someone can light me ?
> >>> > i put in attachement an example.
> >>> >
> >>> > Thanks.
> >>> > Spider
> >>> >
> >>> >
> >>> > --
> >>> > Luddnel Spider Magne | Director - Lead Motion Compositor
> >>> > 555Lab – Alchemy between you and us
> >>> > 24 rue du Pré St-Gervais 93500 Pantin
> >>> > Office (+33)148 453 555 | Fax (+33)171 864 387
> >>> > Mobile (+33)699 434 555 | 555lab.com
> >>> >
> >>> > _______________________________________________
> >>> > Nuke-users mailing list
> >>> > [email protected]
> >>> > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users
> >>> >
> >>> >
> >>> _______________________________________________
> >>> Nuke-users mailing list
> >>> [email protected]
> >>> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users
> >>
> >>
> >>
> >> --
> >> Julien Chandelle
> >> GSM : +32 (0) 494 277 542
> >> julienchandelle.be
> >> || Nuke , AE & Fusion Compositor ||
> >>
> >>
> >> _______________________________________________
> >> Nuke-users mailing list
> >> [email protected]
> >> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users
> >>
> >
> >
> >
> > --
> > Luddnel Spider Magne | Director - Lead Motion Compositor
> > 555Lab – Alchemy between you and us
> > 24 rue du Pré St-Gervais 93500 Pantin
> > Office (+33)148 453 555 | Fax (+33)171 864 387
> > Mobile (+33)699 434 555 | 555lab.com
> >
> > _______________________________________________
> > Nuke-users mailing list
> > [email protected]
> > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users
> >
> >
> _______________________________________________
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