Convert log to rec.709 automatically with RCM | DaVinci Resolve Tutorial

[Music] welcome my name is Avery Peck and today I'll be showing you some really exciting stuff not only will you learn how to convert your log footage to rec.709 automatically but I'll be introducing you to a critical concept in professional color grading called color management that might sound a little technical on the surface but it's the key to matching footage from multiple cameras it also takes almost all of the guesswork out of your color correction and it makes your graded images look consistently good across multiple displays the better you understand color management the more time you'll spend color grading and the less time you'll spend pulling your hair out in frustration so let's jump in first of all what is resolve color management or RCM the basic concept is really simple you tell resolve what color space your footage was shot in and what color space you want to be working in resolve at that point uses an algorithm to convert all of that image data from one color space to the next now that sounds cool but resolve color management is more than just a feature in many cases it can be a real life saving workflow let's say you're shooting a production on three different cameras a red weapon shooting in red log film a Blackmagic Cinema Camera shooting in BMD film and a sony a7s shooting in s log even though these cameras are shooting the same thing they all save their color and luminance information differently to get the most out of each sensor now eventually that footage makes its way to you the colorist and the goal is to correct the footage so that it all looks right on a rec 709 display like a TV or computer monitor in a non color manage workflow you have two options the first is to try and approximate the look of rec 709 by hand in this case you're trying to decode each cameras proprietary color space by eye which is not only time consuming but its imprecise and you'll never get the three cameras to exactly match the other option is to try and use Luntz to convert but most rec 709 Luntz do their conversions a little differently so again you're in a position where you have to tweak the corrections by eye to get the color space conversions to look correct however with RCM you simply tell resolve what color spaces your footage was shot in and what your target color space is resolve then exactly decodes each cameras color space and converts that image data into rec.709 in this case each camera is now on a mathematically level playing field and matching these cameras becomes extremely easy the best part is resolve is doing all of this conversion automatically across your entire timeline so it's not only the most precise method but it's also the fastest now moving forward once your project is color graded you deliver a rec.709 image that looks great for TV but let's say you're also told that the footage will be screened in a theater well theaters use a completely different color space DCI p3 and trying to screen your rec.709 image on a cinema projector will look totally wrong in a non color managed workflow you actually have to go through and recolor your entire project to match this new color space with RCM though all you have to do is tweak your color management settings to fit the projector then you just make a few final tweaks and send it off to the theater where the grade will look exactly the way you intended on the silver screen all right so now hopefully you see what the big deal is about RCM now I'll show you how to set it up okay so we're back in resolve and real quick I want to just point out that I have a bunch of clips in my timeline and many of these were shot on the Blackmagic Cinema Camera however we have a couple of Clips right here that were shot on the sony a7s in s log alright so let's go back to our original footage and let's start setting up our cm so I'll click on this little gear icon in the lower right hand corner and that will open up my project settings page now I'm gonna go to the color management tab and this is where all of our color management settings reside now we can activate our cm by changing our color science from DaVinci why RGB to DaVinci why RGB color managed so it's the same color science but now we have some new color management options available to us the first one is input color space and this is the default color space that most of your footage was shot in in my case most of this is from the Blackmagic Cinema Camera as I said so I'm gonna change this - Blackmagic Design film now the timeline in output color space should both be set to whatever color space you want to be working in and in my case they're already set up to rec 709 gamma 2.4 but of course you can choose from a long list so let's go ahead and click Save and right away you can see there is a conversion going on but it doesn't look great this is because when you take a large color space like log that has a wide color gamut and lots of dynamic range and you try and cram that information into a small color space like rec 709 you can oftentimes get some extreme values notice how our highlights right here are harsh and are clipping pretty severely thankfully our cm has a really elegant solution to take care of this problem so let's go back to our settings and first I'm gonna focus on this setting right here called the timeline to output tone mapping this is a way to map all of our luminance information or our dynamic range from log into rec 709 in a way that looks a little bit better to the eye so I'm gonna change this from none to luminance mapping and this will apply a luminance curve to better map our information so if I click Save now you can see it's doing a better job of retaining our original values but you can still see that those highlights are a little bit harsh so let's come back to the settings and we have this parameter right here called the max timeline luminance and it's currently set to a hundred nits now to understand what this parameter does you have to understand a couple of things first off your footage has a certain amount of dynamic range and your monitor also has a certain amount of dynamic range that it can display the max luminance that your monitor can show is measured in nits now old rec.709 displays top out at about a hundred nits and you can see that the highlights of the footage extend beyond what the monitor is capable of showing and that's what's happening here because this parameter is set to a hundred nits but if we tell resolve that our monitor can display more luminance information then notice how the footage is now completely contained within the range of our display you can therefore adjust this nit setting to control how much dynamic range is mapped to your monitor now if you technically want to be accurate you can look up how many nits your monitor can display and enter that value right here every time you set up RCM personally though I like to cheat this value up a little bit to help retain some of my highlights so in my case my monitor is actually capable of showing 300 nits but I like to enter 500 here so that I get a little bit more information so I'll go ahead and click Save and notice now how those highlights are brought right back into view and they're no longer clipping on the scopes I can turn my saturation down to zero and you can see those highlights are right at a hundred percent so I'll bring this back up to fifty now the other thing we have is something called saturation mapping so I'll come back to our settings and right here we have the timeline to output gamut mapping and this is just like luminance mapping but it works for saturation values because sometimes you get some wild color values too so I can set this to saturation mapping and the way this works is actually much simpler we have the saturation knee which is basically the threshold where saturation mapping starts to kick in and by default it's set at ninety percent and then the saturation max is the maximum saturation value that's allowed in our conversion so in other words any values that are above 90 percent are mapped in such a way that they never exceed a hundred percent so I'll click Save and we don't really see a change in this shot because we're not dealing with extreme color values but if you are dealing with the extreme color values you'll notice those values are now kept in check much better now let me show you what's really convenient about this RCM workflow we set this up so it's looking good for this shot but if I come over to my other shots you can see that they are undergoing the exact same conversion process and we're getting a really nice rec.709 look out of this that first of all is mathematically accurate and it's also pleasing to the eye so all of that footage now is in a much better starting place now remember that we also have some footage that was shot on the sony a7s in s log and so right now the conversion isn't looking correct because our CM is assuming that this was shot on the black magic which it wasn't so we can come back to either the edit or the media pages we can right click on any of the clips that we want to convert go to input color space and select the color space that this was shot in so in this case this was shot in s log2 so I'll select that and if I come back to my color page now you can see that this footage is being correctly interpreted and it's using all of our same tone mapping settings now I noticed it's a little bit overexposed so I might bring the exposure down slightly and balance out this shot and you can see it's very quick and easy to balance these shots now here I also have some footage that was shot on the black magic and if I want to it seems a little bit underexposed so I can bring this up and just kind of balance it based on the Scopes take care a little bit color cast issue there and you can tell right away that we can actually get our footage pretty well balanced in just a couple of seconds because resolve is doing the majority of the heavy lifting for us so now that you know how our scheme works I want to answer a couple of common questions about it the first is what if my cameras color space isn't on the color space list well first of all I can say that the vast majority of cameras already use a rec.709 color space so if you're shooting on something like a Canon t6i or a Canon 5d or anything equivalent you're probably already in rec.709 however if you are shooting in some odd color space that isn't on this list just know that resolve is adding to the list with every update the second question is is converting your footage with the LUT the same as converting it using RCM and the answer is no a lot is obviously just a table of values but RCM on the other hand is actually a floating-point algorithm and there are two key differences the first is that RCM allows us to control how the information is map from one color space to the next so generally we can get results that are much more pleasing to the eye the second big advantage of RCM is that it's non-destructive so even if you get any information that clips that information can easily be brought back with a LUT on the other hand if you get any information that clips that information cannot be brought back after the LUT is applied the final question is what about ASIS now aces is another alternative to RCM but it's not the same when we use our CM and we set our time line and output color space to rec 709 it's important to understand that all of our controls are now actually mapped to the rec 709 color space meaning that they're using the rec 709 primaries and gamma curve what this essentially means is that our controls are going to respond exactly the way that you'd expect them to for this footage now if we use aces on the other hand even though it will look like your footage is in rec 709 it's not your footage and your controls will be actually mapped to the Aces ap1 primaries and one of the aces gamma curves which are significantly different than rec 709 what this means is that your controls are going to respond very differently than you'd expect them to and sometimes that can be a little bit frustrating and difficult to get used to however if you're semi-professional or a professional colorist I recommend that you get used to using both aces and RCM if you found this information useful go ahead and share it with a friend my name is avery Peck thank you so much for watching this tutorial and I'll see you guys next time [Music]

Channel: Avery Peck

Views: 136,544

Keywords: davinci resolve, resolve color management, rec 709 lut, log to rec 709, matching cameras, how to match cameras, color correction, professional color grading, color space, ACES, s-log, blackmagic cinema camera

Id: DGY14ygjpLU

Length: 12min 30sec (750 seconds)

Published: Mon Jan 15 2018