Nuke 102- CLASS 4- Advanced Keyer: IBK Colour/Gizmo In Depth

okay in this lesson we're going to talk about the IBK gizmo /color this is the most widely used keyer in the industry both in commercial as well as film so I want to talk about a couple of different methods that people use when approaching it now when you're using this keyer you have to choose between this or usually key light in regards to what will be the keyer for green screen type of work there's also of course the luminance keyer and so forth which is basically a keyer so if i just type in you know key or whatever this keyer has you know you know green screen it has green keyer so there's a lot of keyer there as you could use as well if you find that those are useful but the most common ones obviously are key light IBK color i pick a gizmo so i just want to kind of go through what i've learned about the IBK through a lot of industry folks i'm going to go ahead and type in IBK color here now it's common there's two different techniques when doing the IBK gizmo and you'll see this a lot within tutorials and that is there's what's called the daisy chain operation which involves a whole bunch of IBK colors that are sort of connected together like this you know and that sometimes work and sometimes it doesn't it's really I like to try both whenever I get into a keyer and this is a perfect example with Jack here because you're going to find as I get to a certain situation like right here where we have this little hole here and this is real there's actually like he's wearing a weird sort of a thing I put around his neck to try to make the same look futuristic in my own pathetic way but there is a hole here as you can see which is like green and it's hard for the keyer system to get ahold of these little areas so the sampled color of the you know of the difference of what's behind there you know it's 50/50 can give you weird results when you're doing the stacked method or the daisy-chain method versus the regular method so let's just try the first method I'm going to compare the two so I'm going to first start with the IBK color obviously plug that in put my viewer to it and obvious once again we got to switch this over to green and then here we have the default size 10 which is always a good start and then we deal with the darks so I'm going to pick the darks here and I'm going to go ahead and put a value of say 0.01 is usually what I like to start out with and then I put my cursor on the one and use my middle mouse scroll wheel to sort of basically suck in the image until I start to collapse everything you can see what's going on here as we do this we're slowly moving in and then eventually we're going to have to erode so if I go ahead and take a look at this we're trying to encapsulate everything here so you can see the size here is sort of like a you know it's an extension of a blurred so to speak so you can see if we put this a 10 kind of blurs the image a little bit so we go all the way back down to zero here right this is what we have so we're going to leave this at the default 10 and we're going to do our best to deal with this now like the common way you do with the green dark sphere is you'll you'll keep moving until it starts to explode so it's the explosion you're looking for the explosion is when you start to pull this back and a negative value until the this the senior starts to create this starry you know green little dots and so forth you see how it just explodes off the side and again it has to do with the luminance values from left to right so I'm going to go ahead and just kind of do this until it gets basically right there so again I'm trying to get all that data in there and again you can also bring this down if you want you know if you want to if you find that the value of 5 actually works pretty good you know you can do that but you can see they'll be kind of artifacts beginning here so this is sort of like pre blurring the scene to a certain extent so it's the color expansions I'm going to put that to 10 and now it comes to the fact that you know we can come in here and then start you know eroding this all we could do the patch black we start doing the patch black immediately you're going to see that where we haven't engulfed or you know basically the parts of the image that we need to because it's taking this pixel value here which is black and smearing it this way we talked about this before where it's just smearing it towards the normal Center it's what's happening here and that's why the value is darker which you know if we were to tell Jack the galloway this is not the color that would be back there it would be this color right so I'm going to go ahead and just do I'm going to pull this back on the patch back again and I want to continue to encapsulate this by using in a road so you can see as the road hits it and then we get some issues here right well one of the ways to kind of combat that is using the green light so I'm going to put a value of a point one two put one point one in here there we go and you can see if I start cranking up the value on a positive number above one instead we can start to back off that explosion that's happening there so I'm going to what I can kind of back it off like that and again I'm going to start to increase my road which I might over cranked past the value the highest value goes to five but you can keep cranking that until it just keeps going and going and going and going the problem with this is that if we take a look at the original what we want in an ideal world is to have whatever value this is actually be brought here but we're doing as we continue to erode further and further and further out okay is we're using we're going to be choosing this value of green and that value of green is what's going to get smeared in and used in the difference mat so again in an ideal world this is where the stacked version of the IBK color works in its to get as close to the value just before the nostril starts to you know fade into say the green screen here which gives us a different variation of green but we're basically trying to recreate the green that's behind him in real life okay on the set when he was on set what was the green nose right behind it well it's probably the same value as this right not this so that's what's important here so again as you can see we cranked this down we've got you know brighter values darker values around the edge and so forth but let's go ahead and see what's going on over here so right here it's going to take this value of green and it's going to smear it towards this area and it'll be whatever values here which is probably truly the value that's here is probably the value that's over here and probably but the further you get away from what you're going to smear over it's the more variations you're going to start to lose detail or things are not going to work out too well but again I had found that there was a lot of people in the commercial industry that were like oh oh use the stack stack method of IBK color which I'm going to show you in a minute and it works so much better than the just using one IBK color as opposed to a whole bunch of IBK colors and we found that it depended on the shot honestly depended on the shot if it worked for the better for the worse so I recommend always kind of experimenting with both methods so here's IBK color and I've eroded it down so that there is no remnant of any you know blurry edge because this guy's really out of focus we shot this at like a 2.0 f-stop so it was pretty pretty blurry along the edge there and now I could start patching in so now that eyepatch black its smearing in that color in and that's what's it eventually going to do here so I'm going to just grab this use my middle mouse scroll wheel and just go ballistic on this I'm going to go to keep going till it just sucks it all the way in and there we go now if we compare the original to this it's as if Jack got out of the way like we told them get out of the shot Jack so the value here though is most likely that value there I mean it's probably not too far off right again this is the same color all the way across the board here there is no gradient here which probably existed but because Jack is you know nowhere to be seen in this shot you know I mean he's occluding what would be the background this this information isn't too worrisome that we have this sharp fall-off here as opposed to a gradient but what's important is you can see if I just take this the value is the same between here and here see that I mean roughly I mean it's pretty pretty rough there is a variation of change here you can see as I scrub back point the values of red green blue are changing but in general it's holding up pretty good so you just you know keep it simple you just got a go back and forth between your final IBK color and your read node and go does it look like I told Jack to get off the screen get out of the way and it's the background and don't worry about this weird sort of like you know area here that's you know that looks kind of you know it's a government abrupt you know contrast between two different edges here you can see it does look good right okay so that's one way of doing it so let's go ahead and I'm going to show you another way so I'm going to go ahead and put IBK color in here again and I'm going to do the stack method so let's go ahead and put that in again we got to switch this over to green mode here and then again I do the same thing again I'll put like a point one value in here and I will start to crank that up get it as close as I can and here's where things can get messy and that's where you might want to maintain this area because the green that's behind him might actually be a darker green but in this case the hair from the size is actually causing issues I'm going to take the size down to zero right and you can see what it's trying to do let's add a value of one there so you can see it's a lot darker so keep that in mind as we go through this process right so I'm going to go ahead and try to get as close as I can and again you can see we lose it right there so I'm gonna go to my lights and put a value of one point zero one and let's start to crank that up so we can clean up that area there we go you're going to have the more of a badly lit green screen you have the more you're going to have to start fiddling with these two values because there's such a contrast and luminance between the greens here and say if you had a little bit of a patch of red like dark red over here maybe a flare from that light you'd have to come over here to maybe the the red lights whatever the color it is that you see is polluting your green screen that's the color that you want to actually dive into so in our case we have a very warm light over here if we had a flare we can you know fiddle with the lights and the darks of the red and that should start to cancel out those areas the same thing with blue obviously we don't have a blue green screen in this circumstance but you could also fit a little bit with this mostly you will usually leave these alone but mostly you're fiddling with these guys right here so now that we've done this you see the reason why we do this is so that we can get a closer value as opposed to have any value over here smeared all the way in and sample this that the actual back plate of a clean plate we want to get a value that's right here a lot closer it's going to give us a way more accurate reality okay so with that said you can see that we have this and again I'm just going to go ahead and bring this in a little bit more you can see it keeps breaking again I'll bring this up again a lot of your work a quality of work will depend on how well somebody looked at green screen I purposely lit this like crap and you can see we got a hole here so I'm going to go ahead and just Eero it a little bit try to Road that in a little bit and again oh I'll drag it in just a hair and you can see we've already lost this area here you know which is not good okay so now that I've done that I'm going to take this IBK color copy it right and again you can see I didn't do any patch black on this one right I did everything here the size is very low now I'm going to take this guy and now we're going to patch black this at one and you can see what happened it has taken two values here and shrunk them in which is what we want right so here you can see the value here is going to be the value here it's not going to be the value way out here zoomed in so this is an incremental process with the patch black and going to take the erode I take it down to zero so here's the first one here's the second one so you can see what has happened we are introducing a gradient here because we didn't get everything so if you see a gradient happening here which we can see here very subtly right if I bring down the slam the gamma here you can see the gradient so if I go back to my original IBK color I might need to erode this a little bit more you can start to see it go away see that so again we're getting a little too crazy but there's now a sudden we don't we don't have that contrast right now we got to see if the screen explode no it didn't problem is this badly lit green screen is so bad that you know you could like I said you could come in here and fiddle with the blue so you can come in here and do like blue lights on dew point zero one or something and you kind of fiddle with that and so forth so you feel but anyway with that said let's go ahead and take that and again we're going to copy and paste this this IBK color and we're basically going to be squaring the value here so go ahead and put this to two okay so here's that let's look at the progression one two three see how it's slowly getting sucked in and those the why is this important well if you did have little circles and holes in your seen small little patches it's going to localize to that area so that's why it's important not so important on this shot but if you had like like that little hole there we managed to maintain that hole so if I come back here you can see I haven't maintained the hole at all because we had to erode so much but it would actually shrink it in I'm going to show you this in future examples as well how it's beneficial so again to the next one we're going to go to four this is keeping everything localized in regards to the localized sample of the green screen right and then I'll take this again copy and paste it come over here make it an 8 right and then we're just doubling it each time so again this one's going to be 16 creative Lyons tutorials is a great YouTube site um if you I'll put a link in the YouTube for this check it out guys I'm telling you this guy is a genius he's a he's worked at almost every studio I mean he's an absolute genius and he's been really kind to put training videos online and you can almost say that what I'm showing you here is a certain extension in the future episodes of this of what he did but I'm kind of showing you what I learned in the industry which is a combination of that and what he has done so you can see this one is 816 and now the final one we can go ballistic with we can take the final one and close close up shop so I'm going to take this and just keep pulling this until we get you know this thing's you know squeezed in like that there so let's take a look at the different variation between the two so we have again I'm going to try to organize this a little bit nicer for the sake of presentation there we go move these up stack them nicely okay so here's the difference one two you see a difference there there is a luminance difference here here and here and then over here you can see due to the fact that we probably didn't road enough we're getting the artifacts so when you see this and this is hair and this is why I always say there's another method I'm going to show you when you're dealing with hair with lots of transparencies in the hair such as somebody such as Jessica here it was Jessica has you know all these little details in the hair there's going to be very difficult to erode not get these weird smearing artifacts so you can see like what's this all about right well let's investigate go over here it's probably the fact this is a very blurry edge and we didn't row it enough so if we go back to our first color you can see we did get it but I don't think we got everything so you can compare the two see there's still some slight influence of this right here okay so again I can come back to my first IBK color put my viewer here and see if I can kind of get rid of that oops actually it's this area right here let's go and take a look at it there we go so there's the issue right so the the problem child always be your first IBK color so if we go and take a look compare cross compare this IBK color with this IBK other color you can see we still have the influence of the gradient of the you know visor glasses coming out too far so I may have to come into this first IBK color take the erode and just crank it up just a little bit more and then you'll see this as I kind of look at my last IBK color it's going to propagate down and again I'll take my road and pull it back or so you can see fit go ahead and kind of add some contrast here so you guys can kind of see that so you can see it there and it's good to slam your gama a little bit you'll be able to see this so as I increase the erode on the first IBK color you can see what's happening here the key and all of this is to have your IBK color your first one as close to the edge as possible but still capsule a ting all the goodies now as we increase this you can see that we're really starting to reach out to points that are further away and here's where problems occur along the edges here because now we're having an issue where you know we've encapsulated this area so this color is what's going to get finally brought way up here which we know the luminance difference between here and here is very very different so that's the only bad thing so let's go ahead and see what we get in the end good put this back so here's the first here's a second let's take a look at the two they're not that far off actually not far often again the benefit of using this technique is if you have a lot of Swiss cheese holes and whatever you're dealing with whether it's a it's a set where there's a million pieces running around you know in your set and there's like little tiny holes in between the different things that are being green screened that's when you want to use this whereas this again works pretty good as well so let's look at the cross comparison between these two and again it's apples and oranges you're going to find that it's going to work or it's not going to work so I'm going to go ahead and create a switch node really quick and I'm going to plug this one in here in this one in here and I'm going to use my foreground object as in the original plate which we're going to go ahead and we should have done which we should have denoise this but that's okay let's go ahead and put that into the color and now let's go ahead and just take a look at the difference so this is our first one set up and again we need to set this to green so I'm going to hit a for alpha and just see at first what we have so this is actually a you know we want this mucky area here probably the D grain will take care of a lot of this noise but you can see if I kind of sample this all down control and shift you can see the values here are point zero zero I'm sorry one this is actually acceptable to put on a back plate believe it or not despite the fact that it's very noisy here because the reality is is any value between zero and zero point basically Oh point zero five or lower is acceptable and usually won't hold a trace in your final footage in the sense of you know your what's commonly called your fringe matte which this would be your fringe matte a core would fill in all the holes you can see we're having issues with this highlight here on the nose we're having stuff here here going on again it's really important for you to look at your footage and examine what is going on like why is that and play play through the footage see where you're getting holes and you can start to see where problems are now here you can see all the hair detail I'm going to go ahead and put my viewer to this and you can see we're getting all this hair detail and sometimes to check this I will add a shuffle node it's just like sort of like a quality assurance check and I will take the shuffle node and flood my alpha channel to my RGB so now as I'm looking through this shuffle node and I go to RGB I'm looking at the alpha and now I can go and look at the original so you can see how much detail I've lost someone should may be going a little bit overboard look at the matte line you know this is the gradient here that looks about right but it probably could be crushed a little bit because you can see the actual luminance is a little bit further out here so if I go to my IBK color there's a couple options here as you can play with one is the red Waits and this is the red bias here you can see if I kind of go back and forth you're getting you know back it's usually you leave these by default most compositor tell you to not really touch these if you do you maybe move them about this far you don't go any crazier than that so let's go ahead and play with the blue blue green which basically means that if you're doing with a green screen you're only usually adjusting the blue weight and if you're using a blue screen that means you're using the green wait' so this is not blue and green this is actually just whatever the opposite of your screen is so in this case we have a green screen hence this is dealing with the blue weight so you can see as I kind of refine this it's looking good over here let's see how it looks over here as we're bringing back all of the reflections here so it is a double can be a double-edged sword we have a luminance match which we can click and that will start to restore areas such as where there's the highlights of the nose you can see right here so for instance if I go back to in here and I can play around with this you can actually take your luminance match and you can start to bring it up and down so you can see if I just you know kind of bring it back and luminance level usually you don't want to fiddle too much with this you can see how it can be used to kind of somewhat bring back the detail later but it also introduces some stuff so I'm going to go ahead and leave that off you can see luminance match can work in bringing back areas of bright highlights so let's go ahead and just see the influence of that off and on always look at the off and on see what you gain see what you lost right so that's looking pretty good you also have Auto levels on here this has to do if you have a highly saturated colors such as highly saturated yellow cyan or magenta 's in our case in this specific case that actually might work to our advantage again we can come in here and just play with these the more you fiddle with the more you again I use the word quoting tampering in God's domain the more you're going to have a lot of issues here so if I turn this to yellow right you can see that it's trying to do its best but you start to get a harder edge and I miss that so again I could use magenta and you can kind of see if it's really kind of bringing back all those heavily saturated areas and again I would say we just leave it off again you can try try yellow something a little bit but yeah you got to fill it with it now screen subtraction use background luminance use background chroma I don't want to get into this there's other tutorials that go over this this is more long lines if you do all of your compositing within this one compositing node just go online and look up a tutorial on IBK gizmo and you'll find out how to do this Steve Wright is a great reference for that but again you I we're creating the mat here we're not worried about anything else although these are you very very useful tools on their own if you composite straight in but we want to make a separate mat for the actual mat and we have a separate area for the D spill which is RGB information and we usually combine the two so that'll be in the next video I'm going to talk about but anyway so with that said we can come in here now I'll go ahead and get rid of shuffled Oh actually I'll leave it in all the way at the bottom is a cute Quality Assurance test and let's go ahead and I'll switch back the Alpha here and now I can come in here and then go ahead and just do a simple grade note here so take a grade node I'll set this to alpha and we can go ahead and start to crush the blacks now there's a big debate on the Alpha that precedes the IBK gizmo some people like using crushed and black points to get rid of some of the noise right again you you're winning the battle but losing the war as you can see as I crush this the hair is getting chopped right there's also the option to click on such as white clamp here and kind of fiddle with the gamma a little bit that's another option right and also some people sometimes play with the multiply option bring back details so those are the three Biggie's that you'll commonly see within this grade node another option you can do and I'll go ahead and just leave this I'm going to offshoot this and I'm going to go ahead and choose what is the color lookup so the color lookup will allow you to there's a whole bunch of other tools you can use here is if I go to my alpha channel here in here and again I'm going to affect the Alpha is I can take this here and hit H to make it horizontal and I'll put this and make this H make it horizontal okay so now you can see as we are crushing the whites up to a point nine value and crushing the blacks at a value of 0.1 right you can kind of imagine this as being a zit zit like a Z shape but it's having a fall-off of a gradient which gives you a nice more pristine look than say if I come in here and crush the blacks which is more linear in nature not logarithmic so you can see the difference between the two so let's go ahead to the color lookup and go back to elephant here and what you can do is you can slowly start to inch this by clicking grabbing it and right click left click and dragging it over you can see we're sort of dragging in cleaning up but we are cutting off his hair right so there's all types of things you can do in here you can actually come in here if you want and you can go ahead and click your left mouse button and drag this up and this is giving you a logarithmic fall-off for you know for the crush so you can see it back and point so that is an option that you can use let's talk about the switch in between the two different versions here and go back to my IBK gizmo here really quick and I just want to show you the difference between the old version new version right so let's go ahead and click it and give it a minute here you see a difference most people would tell you that this method is always use this method don't use this method oh no no no no always use this method don't listen anybody that has you know it says this always works it always works it always works you know not everything works in every situation compositing so just be aware that do you notice that there is a loss of hair detail look at that dramatic loss of hair detail now why is that well let's take a look at the two different versions here is go ahead and go back to RGB there's this version and this version we have artifacts here but you know in the process we didn't need further enough out as you can see that is one possibility so if you've seen any weird artifacts here that are going to be an issue the other thing is there is definitely might be a little bit of a luminance change in between the two variations and that is because in this gizmo let's take a look at it we are sampling a value to come down here kind of move through this you're going to find that we're going to be sampling this value all the way up here so you know it's it's the distance of a different variation of color that gives us a little bit of a difference so again you can see the difference here right and then anytime you see this kind of stuff is a big warning sign okay that's what's going to probably cause issues and a lot of has to do with your first IBK color we go back to it you can see it doesn't include this hair material here so one of the ways around that is by introducing a sort of inclusion of the mask all this is doing if I put my viewer to this color no a for alpha is it's basically defining an alpha edge that's all it's going on here so you can see this area right here is black right so what I could do is I can create a I can come in here and artificially introduce more of a cutout mat so I can go ahead and add a merge node here and this is common when you're dealing with people with heavy fluffy hair like Jessica you know with holes in it and the erosion process and the keying process because they'd be here or the background color is so different in the variation again if you have you'll have to do this most likely if you have a poorly lit green screen is to come in here and manually cut that stuff out so I'm going to go ahead hit Oh for roto plug that in right so let's go ahead and look at our viewer here and I'll go back to my RGB and I'm going to purposely cut out this area here I want to use a busy a cost let's go ahead use a pezzi a and I'm going to go ahead and get as much of this crud out of here without affecting the original piece so now you can see if I take a look in my alpha edge here I have to put my merge mode to stencil and now you can see I've cut out or added to this this is the defining line that's going to be used as a smear line so whatever pixel value that is here in the green is going to be smeared in so again I come into here now and you can see it's doing just that right and in this case obviously it's grabbing this value which is if we denoise this would probably we have a better better deal here but again I might need to take my roto node push it out even further and doesn't look like it's doing much so you can see in this case now we're getting this interesting artifact and the reason why this is happening is because this is not aliased so you can the its anti aliased we have this kind of hard edge here so one of the ways you can do that is you can add a grade note in here and you can go to your alpha Channel put it to alpha if I take my white point and I drag it to 0 I get absolute hard edges now let's take a look at what we get now kind of go down the play period of this color node there you can see that's gone so you see without it we're getting an artifact because the alias aliasing or anti aliasing but once it's a hard edge we're good to go so that is proper now so let's go ahead and look at the final results and again I'm going to go back to my alpha and look at that now again we probably could denoise the plate but you can see an introduction that's different let's go ahead and turn this pencil on and off and we'll see what has happened now we've retained these new hair follicles you see that and that's all because of the fact that again we can clean this up if we can't go down the chain here get to this stage and these values if we sample them are actually point zero or two which are acceptable to be layed on to an actual back plate without being visible as noise so just keep that in awareness as you kind of do this so this is a great technique for taking into taking out stuff and so forth so again this is the different methodologies that you can use they work really well obviously we need to create a film at for this area here or a core mat I should say that actually fills in these areas there will come a time though where we will probably have to come in and do a little bit of paint work or animated roto work specifically maybe around the edge of his head here so if we go to the original footage here you can see we have this green influence here on his uh you know it gets pretty close see if we can find a good good frame here yeah so this stuff this stuff can be tricky obviously so you can see if I put my viewer to the gizmo here and go to a 4 alpha you can see this sort of working here and that's where we do some rotopaint work so we're going to get into that but again I just wanted to show you the you know of all of these different realities what it best works and then you can decide maybe I got to use the key light for just one little segment here one little segment here sometimes you will want to use the key light just to be aware so as I was talking about this stencil method if I was say doing an example here of Jessica so I'll jump back to RGB here and you know in Jessica's situation she has these you know hairs hair that are all over the place you will never be able to get ahold of that information you can see there is a variation here right this this green is different than this green here so I it's so important to let your green screen really well and I purposely made this green screen lit badly so that we can do this example because even if you tried if you can get a little sample of color here there's going to be pollution by her hair in the shot do the blur so it you're going to have to sample way out here to bring it in for this and the best way to do that would be again use that stencil method and come in here and just maybe chop out this hair here and put a stencil in you could even go as far as out here that way you maintain the erodes / settings but you're extending it manually with this and of course you're gonna have to animate this as well so in the next tutorial we're going to talk about D spill and before we get into our uber key

Channel: VFXforFilmmakers.com

Views: 52,641

Keywords: nuke, nuke keyer, ibk, ibkgizmo, ibkcolor, advanced keyer, primatte, green screen, keylight, foundry, creavielyonstut, lyons, creativelyons, uber keyer, professional, stacked IBK, IBK

Id: EALBwyXXVFE

Length: 34min 52sec (2092 seconds)

Published: Sat Jul 08 2017