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

Wed May 28 06:07:00 CEST 2014

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_Presets I 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 PagliaVfx and Production Supervisor
mobile  +39 347.82.12.473e-mail   f.paglia.80 at gmail.com

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