[Bf-compositor] Clamping (Mix, Math, RGB Curves)

David McSween 3pointedit at gmail.com
Wed May 28 07:57:01 CEST 2014


I would certainly be interested in a 'colour matcher' node group.
Especially if it Rock My World as Mark says in the link ;-)

These look really useful, it would be great if everyone could at least
match pedestal across their elements.


On Wed, May 28, 2014 at 2:07 PM, Sean Kennedy <mack_dadd2 at hotmail.com>wrote:

>  Hey guys,
>
> I made a few nodegroups we were discussing.
>
> https://www.dropbox.com/s/uj9kw6dm1sp3cot/clamp_nodes_screenshot_02.jpg
>
> I made a Value clamp, as Deigo had made. Then I made a RGB clamp, where
> you can set R, G, and B individually. And then I made the node I really
> wanted, a black levels node.
>
> When you're compositing one image over another, and they come from two
> different sources, they usually have completely different color values in
> the highs and lows (obviously, we all know this). At R&H, we had a great
> Black Levels node where we could simply sample a dark spot of a background
> plate, and the darks of the foreground plate would just shift to match.
> This works the same exact way. It was ideal for CG elements going over live
> action plates, because usually the general highs and overall color of the
> CG matched the plate fine, but the blacks always came in as absolute
> blacks, or sometimes negative blacks. This node made fixing it a 1-click
> operation.
>
> If anyone is interested, I can upload a blend file with the nodegroups.
> The clamps are super easy to make, though. But maybe the black levels one
> would be interesting to someone?
>
> Tomorrow I'm going make a node setup to easily replicate Mark
> Christiansen's techniques for matching the general colors of one plate to
> another. You can see the technique here in the free sample videos, if
> you're interested.
>
> http://www.lynda.com/After-Effects-tutorials/After-Effects-Compositing-Essentials-Matching-Foreground-Background/114913-2.html
>
> It's fun making these!
>
> Sean
>
> ------------------------------
> From: f.paglia.80 at gmail.com
> Date: Sun, 25 May 2014 09:50:01 +0200
> To: bf-compositor at blender.org
> Subject: Re: [Bf-compositor] Clamping (Mix, Math, RGB Curves)
>
> Thanks for the advices Diego and David!
> Just a little thought:
> Adding lot of nodegroups in a single "category" - I mean in the same menu
> list - isn't that efficient... is there a way to manage their position in
> the SHIFT+A menu?
>
> Referenced node group are quite "risky" since compositing session works
> most likely WYSIWYG and as soon as you change something you have to check
> back each project... but I get your point Diego... I'm very used to linked
> group, they are so useful and I hope they will be empowered a lot with
> gooseberry since Proxyfication have room for for lot of improvement.
>
>
>
>
>
>
> 2014-05-25 4:26 GMT+02:00 David McSween <3pointedit at gmail.com>:
>
> Don't forget the addon Node Presets
> http://wiki.blender.org/index.php/Extensions:2.6/Py/Scripts/Compositing/Compositing_PresetsI think you can add node groups and store them in a portable file.
>  On 25 May 2014 09:59, "Diego Gangl" <dnicolas at gmail.com> wrote:
>
> >> It is possible to clamp (blacks and whites individually even), but
> >> whenever I want to do it I have to add gazillion nodes. It takes time.
> My
> >> intention is to make it with a single click.
>
> You can turn them into a group, plug the math values into group
> inputs, name it and bam! your own Clamp Node that you can add from the
> group menu.
>
> > Isn't there a way to develop few nodegroup store them somewhere and
> recall
> > them in a personal group list or add them in the lists we already have?
>
> There's two ways:
>
> 1- Make the groups in a new (empty) blend file, then save it as your
> start-up file (ctrl+U). The node groups will be available in every new
> file you make.
>
> 2- Make a "Node Library" file. Make all your groups there, then make a
> new empty file and link all the groups from the library file. Save it
> as your start-up file and you get all the groups. The cool thing is
> that if you tweak the groups inside the lib file, they will be upated
> in all the blend files that link them.
>
> Gooseberry is going to bring a lot of developement into asset
> management, so it will get better.
>
>
> 2014-05-24 7:00 GMT-03:00 Francesco Paglia <f.paglia.80 at gmail.com>:
> > Isn't there a way to develop few nodegroup store them somewhere and
> recall
> > them in a personal group list or add them in the lists we already have?
> > Could it be a python add-on?
> > This would help us skip the tedious part of reloading those node every
> time
> > a new blend file is created and also could help us distribute those
> nodes in
> > their coherent place.
> >
> >
> >
> > 2014-05-24 11:31 GMT+02:00 Bartek Skorupa (priv)
> > <bartekskorupa at bartekskorupa.com>:
> >
> >> It is possible to clamp (blacks and whites individually even), but
> >> whenever I want to do it I have to add gazillion nodes. It takes time.
> My
> >> intention is to make it with a single click.
> >> How much time did it take you to set up this fantastic node tree of
> yours?
> >> If it's more than one second - itś too much. It should be: Decision => 1
> >> second later: DONE.
> >>
> >>
> >> Bartek Skorupa
> >>
> >> www.bartekskorupa.com
> >>
> >> On 24 maj 2014, at 00:10, Sean Kennedy <mack_dadd2 at hotmail.com> wrote:
> >>
> >> Ah, great idea! We could even set one up with RGB, one on each channel,
> >> and save it as a nodegroup.
> >> Thanks! So obvious, don't know why we didn't think of this. :)
> >>
> >> I'm going to set one up today.
> >>
> >> sean
> >>
> >> > From: dnicolas at gmail.com
> >> > Date: Fri, 23 May 2014 19:07:28 -0300
> >> > To: bf-compositor at blender.org
> >> > Subject: Re: [Bf-compositor] Clamping (Mix, Math, RGB Curves)
> >> >
> >> > Hi all, I don't know how Blender's handles colors internally but
> >> > wouldn't this work?
> >> > http://www.pasteall.org/pic/show.php?id=71736
> >> > (or are the V values already mapped to 0-1 from the separate node?)
> >> >
> >> > Cheers,
> >> >
> >> > 2014-05-23 18:46 GMT-03:00 Sean Kennedy <mack_dadd2 at hotmail.com>:
> >> > > Could we set the value of the clamp? It could come in as defaults of
> >> > > 1.0 and
> >> > > 0.0, but we could alter it to whatever we wanted. At R&H, most of
> the
> >> > > time
> >> > > we clamped brights around 14-16. We'd only turn it down under that
> if
> >> > > we got
> >> > > bad pixels when rendering.
> >> > >
> >> > > If you had a superbright red, like R 12, G 3, B 4, and you put a
> clamp
> >> > > of 1
> >> > > on it, obviously it's going to set each value to 1, so what was red
> >> > > now
> >> > > reads as white. But it would still be useful.
> >> > >
> >> > > After Effects clamp tool
> >> >
> >> > > >
> http://cdn.aescripts.com/media/catalog/product/cache/1/image/800x600/040ec09b1e35df139433887a97daa66f/f/t/ft-clamp-ui_1.png
> >> > >
> >> > > Nuke clamp is in the color grade node
> >> >
> >> > > >
> http://docs.thefoundry.co.uk/nuke/63/pythondevguide/_images/getMinMax_01.png
> >> > >
> >> > > I'm not posting the images to say "this is how we should do it", but
> >> > > rather,
> >> > > to say it is useful and professional compositors would indeed use it
> >> > > often.
> >> > >
> >> > > In fact, I was working on a shot this week that could have used it.
> I
> >> > > was
> >> > > given stock footage from a client, and I have no idea how much
> they'll
> >> > > color
> >> > > correct it in post once I deliver the final vfx shot. SO I have to
> >> > > make sure
> >> > > all my blacks are in line with what is in the plate. I put a gamma
> on
> >> > > the
> >> > > plate just to view the black levels and see how they match up when
> >> > > pushed
> >> > > really far.
> >> > >https://dl.dropboxusercontent.com/u/10553822/clamp_blacks_01.jpg
> >> > >
> >> > > Since we don't have a clamp, I ended up putting a mix node right
> after
> >> > > the
> >> > > stock footage node, setting it to Lighten, and making the color over
> >> > > it
> >> > > black. then I slowly raised it while watching until the blacks all
> >> > > came in
> >> > > line. Would have been much easier to sample the value of the darkest
> >> > > dark I
> >> > > wanted in the shot, throw a clamp node on with the black clamp set
> to
> >> > > those
> >> > > values.
> >> > >
> >> > > In fact, at R&H, the Black Clamp node let you set an individual
> value
> >> > > for R,
> >> > > G, and B. And it had a color picker so you could just sample the
> image
> >> > > and
> >> > > the values would fill in automatically.
> >> > >
> >> > > Anyway, just throwing out my $0.02. Obviously I've found a
> workaround
> >> > > and
> >> > > can live with it, but it would sure be great to someday see a clamp
> >> > > node.
> >> > >
> >> > > ________________________________
> >> > > Date: Fri, 23 May 2014 14:21:40 -0700
> >> > >
> >> > > From: troy.sobotka at gmail.com
> >> > > To: bf-compositor at blender.org
> >> > > Subject: Re: [Bf-compositor] Clamping (Mix, Math, RGB Curves)
> >> > >
> >> > >
> >> > > On May 23, 2014 1:56 PM, "Bartek Skorupa (priv)"
> >> > > <bartekskorupa at bartekskorupa.com> wrote:
> >> > >
> >> > >> When I say: "clamp blacks" I always mean: set every value below 0.0
> >> > >> to
> >> > >> 0.0.
> >> > >> When I say: "clamp whites" I always mean: set every value above 1.0
> >> > >> to
> >> > >> 1.0.
> >> > >> Every compositing artist will know what I mean.
> >> > >
> >> > > If we can generate a clamp / scale node, I am all for it.
> >> > >
> >> > > I am saying there is no concept of white in a scene referred model,
> >> > > and as
> >> > > such, you have to be careful as to not write nodes that break the
> >> > > system.
> >> > >
> >> > > It is that simple. No white. No brighter than white. So sorry,
> "Every
> >> > > artist..." is actually "Every artist unfamiliar with HDR work."
> >> > >
> >> > > So a clamp node _must_ not make the erroneous assumption that 1.0
> >> > > means
> >> > > anything special, and rather provide for an arbitrary value range.
> >> > >
> >> > > If this all seems like speaking an alien language, it is precisely
> why
> >> > > I
> >> > > chimed in and said "Whoa."
> >> > >
> >> > > There are already nodes that are broken because of erroneous
> >> > > assumptions. It
> >> > > would be a shame to make more.
> >> > >
> >> > > With respect,
> >> > > TJS
> >> > >
> >> > >
> >> > > _______________________________________________ Bf-compositor
> mailing
> >> > > list
> >> > > Bf-compositor at blender.org
> >> > > http://lists.blender.org/mailman/listinfo/bf-compositor
> >> > >
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> >
> >
> >
> > --
> > Francesco Paglia
> > Vfx and Production Supervisor
> >
> > mobile  +39 347.82.12.473
> > e-mail   f.paglia.80 at gmail.com
> >
> >
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>
> --
> Francesco Paglia
> Vfx and Production Supervisor
>
> mobile  +39 347.82.12.473
> e-mail   f.paglia.80 at gmail.com
>
>
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