How use noise reduction like a pro in DaVinci Resolve

which is better an image with obvious noise or an image with obvious noise reduction i'm going to pick the noisy image every time because viewers have been conditioned to accept a certain amount of noise for as long as movies have been around noise reduction on the other hand is one of the easiest ways for a colorist to inadvertently leave their fingerprints behind so we need to find a way to noise reduce if we can but never in such a way that the image is left feeling worked on today i want to show you a couple of principles that i use to accomplish this in my grading practice let's take a look here inside of davinci resolve and talk about some strategies and some techniques and some principles for noise reduction so i'm currently in a brand new project where i have not done any grading and all i've done thus far is set up my overall color management and my template node tree here if you don't know what those things are don't worry i talk about them a ton here on the channel i've got entire videos an entire series dedicated to them that i encourage you to check out if you want to learn more about the foundation that i'm going to be building on here in today's video so let's take a look at this first image in my timeline here and start to set my primaries like i would always do at the beginning of a grade so i'm going to start exposing things up here let's say that even though the image itself is rather moody i've actually decided i'd like to see a little bit more into that image i'd like to open it up i'd like to expose it up just a little bit like i'm doing right now and let's go over to my ratio node here and adjust my contrast as well whoop that's not the right node up here onto my ratio and we're going to start bringing in a little bit of contrast as well so this is just some basic primaries that i've done that represents more of where i or maybe more where my client would like to see this image go i've opened things up my hair and it's looking pretty good but certainly after having done this when i play through the image and when i zoom in a bit i'm noticing quite a bit of noise especially my subject's face that's the first place that i really notice noise and where i'm really going to decide gosh i think i'm gonna have to do something about that right so what do we do in a situation like this where we're starting to see noise in the image and we need to do something about it we need to do what we can without tipping our hand without making the image feel worked on well a couple principles that we're going to talk about here today but the first one is probably going to be your least favorite one no one likes hearing this advice but i'm going to give it to you anyway because i think it's the most important of the principles that we're going to be talking about today that principle is to lower your expectations yeah that's right lower your expectations when it comes to noise reducing we need to recognize that an image like this where i'm seeing this level of sort of standing chatter and noise in the image it's never going to be pristine it's not possible to get it there and have it feel organic in nature i can completely smooth things out if i want to but it's going to feel completely worked on it's going to run completely at odds with the goal that i talked about at the beginning of this conversation so the first thing we really need to do is lower our expectations we don't need to get all the noise out in order to get some of the noise out and to make a meaningful impact on the image and the other thing that we can contemplate when we talk about lowering our expectations is it may be a matter of lowering our expectations of what we can do with the exposure of the image because if you remember i moved this exposure a lot right like in that very first exposure node so the easiest way to noise reduce this image would actually be just to back that down and kind of move back down closer to what i got out of the camera negative when i first loaded this image in here okay so a couple different ways that we can apply that principle of lowering our expectations i know it doesn't sound fun it almost sounds like cheating to say well you need to move the goal posts but i promise you this is the most important principle of any of the principles we're going to talk about today when it comes to noise reducing effectively in our images that said i'm going to open my exposure back up and let this problematic noise sort of ride and be prominent so that we can talk about what we do when we are experiencing high levels of noise and we need to deal with them in the best way that we can okay so we talked about lowering your expectations let's now talk about the way i actually handle noise reduction in a situation like this i'm going to go down here to the lower branch of my node tree and i'm going to go over here to my noise reduction tab now there are two main types of noise reduction here inside of resolve unless you're talking about a third-party plug-in or something we've got these two categories of noise reduction available to us in this noise reduction palette the first is temporal noise reduction the second is spatial noise reduction temporal noise reduction deals with time right temporal noise reduction essentially looks at whatever frame we are currently parked on and looks one two three as many as five frames backwards and that same number of frames forward and analyzes each one of those frames to try to figure out okay what remains what's something that stays consistent across those frames what is the image in other words and then it's going to say well i'm going to pull that away and whatever is left must be the grain it must be the noise and that's what i'm going to remove that's how temporal noise reduction works and on paper it sounds pretty good right sounds like a pretty clean way to extract the noise from our image the problem is in practice best case scenario you end up with a frame rate or a tempo or a feeling of motion that kind of feels like you're watching a football game on your tv it feels sort of interlaced it feels sort of like 60 frame a second type of thing so i generally will avoid temporal noise reduction in favor of spatial noise reduction which is essentially blur it's a fancy way of saying blur and it's a way of saying blur that we try to impart in such a way that it doesn't obviously problematically soften out the image okay so let's talk about how i use the spatial noise reduction option here inside of the noise reduction tab for mode my preferred mode is actually better faster does not look good and i think enhanced doesn't actually look as good as better does so it's a bit counter-intuitive but i like to use better i encourage you to experiment with all three of these and find out for yourself but my recommendation would be to use better next from here we have our radius right so our radius is where we're going to define the sort of overall scale of our blur how large or small is it going to be the larger it is the more noticeable it is the higher chance we run of leaving our fingerprints on the work as i talked about at the beginning of this video so i'm going to leave this as low as i can my first preference is to do small if small doesn't cut it i'll go medium if medium doesn't cut it i will go large but generally i want to leave it on small if i can and next we have our spatial threshold all i'm going to do here is try to use the least amount of this that i possibly can while still getting the result that i'm looking for in my image now as we have already talked about there's a lot of noise in here so my normal go-to of trying to go with like say 15 or 20 on these sliders it's not gonna work we're gonna have to hit this image pretty hard in order to even get a serious response out of the noise reducer so let's see what happens if we kind of play through the image at this 75 strength here that's starting to look pretty decent we're getting things cleaned up pretty well aren't we we could go all the way to 100 if we wanted to but the other thing to look at is where's the point where you're not really getting any additional benefit you're not really cleaning the image anymore you're just hitting it harder to me that was around 60 70 percent past that point i'm really not seeing much difference i'm just pumping the system harder and not really getting much more benefit out of doing so so i'm going to leave my setting here somewhere kind of in the 70s and say that that's a a good place to you know contemplate parking this noise producer on my image now from here we've got a couple of different options that we can contemplate but one that i will often break out especially in situations where i'm really having to hit the image hard with quite a bit of noise reduction and this for me is about as hard as i would hit an image like i said i'm often trying to keep this slider down closer to like 15 or 20 as opposed to being up in the 70s like i am right now but what i'll often do when i am trying to hit an image hard like i'm doing here is i will pair this noise reducer with a qualifier now any of you have hung out with me on this channel for a little bit might be aghast to hear me say i'm going to use a qualifier but i do use qualifiers from time to time i don't love using qualifiers as a first line of defense because i think they're a very narrow tool but in the right context they're the perfect tool and i do think this is the right context what i want to do is go over to my qualifier and i'm essentially going to try to observe the reality of a digital sensor which is that noise tends to gather down toward the shadows down toward the floor of the light that was hitting that sensor that's where we're going to see most of that light so right now i'm noise reducing up in this area just as much as i am down in the toe of the image down here when i really don't need to noise reduce up here there's not really any noise up there so what i'm going to do instead is go to my hsl qualifier and i'm going to go into my highlight mode here and then i'm going to go to my high setting here in the luminance qualifier and just start to bring things in like so just try to find kind of a decent mat where i'm affecting just the lower portions of the image and then i'm going to crank up my high softness and make it nice and soft and i'll just point out that even though i'm using a qualifier which as i've said i tend to have beef with because it's a pretty narrow option in terms of manipulating the image even when i do choose to use it i'm trying to use it as broadly as i possibly can so i'm not qualifying more than one parameter and i'm being as broad and soft with the single parameter that i'm qualifying as i possibly can okay so let's turn this highlight mode back off and just take a look at what this is doing to my image now and maybe even go back over to my noise reducer and try hitting things a little bit harder like so let's just max it out at 100. and now here in the qualifier i can evaluate just on the basis of the image where is my sweet spot for this high point so somewhere is around here i'm hitting every inch of my subject's face but if i go somewhere down around here i'm getting a good bit of cleanup down here in the lower areas but i'm not getting that sort of strange plasticine rendering in this sort of slightly higher tonal value up here on my subject's cheek that i was getting a moment ago so i think that's a win that is going to help me sort of like bury what i'm doing a little bit more if that makes sense okay so that's sort of another technique that i will often use especially when i'm having to hit the image harder is i'll bring in a qualifier and really focus that noise reduction down into the areas where it matters which tends to be the shadows and the lower mid tones right so that's the other concept that i'll often use here and the last thing that i want to show you is to think about an even more kind of extreme case let's turn our qualifier off for the time being and let's say no really we got to get like all the noise out of here we really really want to clean and sort of like reimagine this image at this exposure at this contrast ratio we want to get it nice and clean we just can't stand any of that original chattery noisy texture that we're seeing we want to get rid of it here's how i would handle that right now i have maxed out my spatial noise reduction but i could actually add another one of this node i'm hitting command c now i'm going to hit option s to add a new serial node and then hit command v and i've just doubled up on my work here i've just added two of these nodes like so and i'm now accomplishing that goal i have pretty well gotten rid of all of that noise in the original image now i'm kind of seeing like a more broad spatial chatter in here and the image feels quite odd it feels worked on it's kind of exactly what i warned against at the beginning of this conversation but we're only one more step away from a pretty interesting result i'm going to do another serial node option s and i'm going to grab an instance of some film grain okay so let's go over here into my effects tab and i'm going to set my opacity for this kind of fine-tooth 35 millimeter grain up to a 1 and i'm actually going to go to my grain strength slider and bump that up as well and then i'm actually going to use that same qualifier trick to say hey i don't need to see all of this chatter that i'm seeing in the sky i want to flag this off and have it just affect kind of my lower mid tones on down so somewhere like so and then i'm going to soften out that qualifier in the same way that i did before and see how we've done so if we take a look at this the main thing that i'm noticing right now is i'm still seeing kind of a bit of like macro chatter from doubling up and maybe hitting this lower noise produ this second noise reduction i should say perhaps a little bit too hard so i'm going to try backing that off to like 33 but other than that if we sort of step back for a second which is really important to do when you're noise reducing or performing any other grading task and resolve if we just step back grab the three adjustments that we've made thus far and look at where we started like that's a win that's a lot better right and this last technique that we're looking at allows me to really do away with virtually all of that original noise that i might just find really really unpleasing or problematic and replace it with a more sort of cinematic type of noise i.e film grade which by the way is exactly what grain is grain is analog photochemical noise it just so happens that as we talked about at the beginning of this chat we said that viewers are kind of conditioned to accept noise viewers are very conditioned to accept film noise because it's been with us for so long so the net results of really hitting this noise reduction hard and then adding some film grain back on top is that yeah we've still got a little bit of noise but it's a lot nicer than the noise that we got out of the camera itself so these are some of the main principles concepts techniques that i like to use when i'm thinking about noise reduction when i'm faced with the need for noise reduction in a grade and they really serve me well and allow me to accomplish the goal that we discussed at the beginning of this conversation where we say hey it'd be great to get some of this noise out of here but the first goal is to leave no fingerprints right if the image feels worked on if someone knows what you're doing you're no longer doing it so we want to operate like color grading ninjas and fly underneath people's radar everything that we've talked about today is a good sort of set of strategies for accomplishing that goal we're going to go deeper on this subject in our next session of grade school my youtube live that we do on friday morning specific time at 10 o'clock so i encourage you to come join me for that if you have further questions on this topic or you want to see us go deeper into it then we have had the chance to go in this video it's my favorite part of the week answering questions talking about these topics getting to go deeper but this is a great start here and i'm looking forward to seeing you in grade school on friday if you want to join us see you then

Channel: Cullen Kelly

Views: 31,805

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Id: RzwQ1Miyjbc

Length: 15min 31sec (931 seconds)

Published: Mon Aug 08 2022