[Bf-compositor] Clamping (Mix, Math, RGB Curves)
Francesco Paglia
f.paglia.80 at gmail.com
Wed May 28 12:15:37 CEST 2014
Hey Sean,
I'm really interested in seeing your node and much more on the match color
node...
I've tried by myself making one but I couldn't find a nice way to have the
setup embedded in a node group.
Looking at the tutorial the artist simply match low and hi valuse of a
levels effects for each channel.
So I though I can mimic that result just with a simple setup:
1. separate RGB of the input,
2. add a color ramp to each channel (to get a remap of Hi and LOW value)
3. add a combine channel to recreate the final image
The result looked promising but
1. to expose the value of the ramp you have to add a driver on each stop of
the ramp
2. the driver (don't know why) in official 2.70 build seems cannot read the
value of a node RGB.output or the input of the group even if it is readable
in the python console (the driver simply show the path background in red
color)
3. value are clamped in the 0-1 range so if values exceed this range they
are remapped.. (well this is a known side effect driven by the node used...)
I'm curious to know your approach :)
Thanks,
Francesco
2014-05-28 7:57 GMT+02:00 David McSween <3pointedit at gmail.com>:
> 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
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>> >
>> >
>> >
>> > --
>> > Francesco Paglia
>> > Vfx and Production Supervisor
>> >
>> > mobile +39 347.82.12.473
>> > e-mail f.paglia.80 at gmail.com
>> >
>> >
>> > _______________________________________________
>> > Bf-compositor mailing list
>> > Bf-compositor at blender.org
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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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