Davinci Resolve: ACES Explained, Part 1

if you've spent any time at all learning about color grading you've probably heard enough about aces to be curious maybe you've played around with it in resolve and maybe you've even gotten some interesting initial results but if you're like i was you're probably still a bit fuzzy on the fundamental questions what is aces how does it work and why should i use it over the course of the next few videos we're going to answer these questions in a practical and concise way and leave you with everything you need to start taking full advantage of aces in your grades and today we're going to begin this journey by looking at what aces is and what it has to offer so what is aces aces or the academy color encoding system is a color management framework for motion images this simply means that it provides a standardized way of transforming what the camera saw into what our display can reproduce with an intermediate stage for color and vfx work now to understand why this is important we need to get straight on some basic image science so i'm going to give you the world's shortest course on human vision and image reproduction ready here we go let's start with the electromagnetic spectrum which spans every form of radiation in the universe x-rays gamma rays radio waves ultraviolet light any form of energy that travels in waves there's a narrow band of this spectrum that our eyes are sensitive to and which we perceive as color consisting of various amounts of red green and blue cameras and displays were built on a similar model expressing color as varying percentages of pure red pure green and pure blue but how do we define pure red green or blue in this context this is where color spaces come in scientists have precisely measured the full range of wavelengths which fall within the visible spectrum and we can see them represented here in this graph a color space is simply a triangle within this horseshoe which explicitly defines the purest red green and blue which a device is capable of capturing or reproducing and just like points outside of our horseshoe aren't visible to the human eye points outside of our triangle can't be captured or reproduced by a device which uses that color space now here's the important part when we know the color space of an image we can transform it into any other color space simply by using the right math why might we want to do this let's say we've captured something on camera a and we want to view it on display x and each of these devices has its own color space the best way to get an accurate reproduction is to mathematically transform the image from camera a's color space into display x's we call this process color management and it's faster and more accurate than doing things by eye and this is where asus comes in aces provides a user-friendly system for making these transformations with support for a wide range of cameras and displays okay now that we understand color spaces and color management let's take a look at how asus applies these principles to take our image and move it from its acquisition state and into a graded display master so let's get a look at the way these color space and color management principles play out practically inside resolve and the aces ecosystem now before we begin i want to point out that in today's demo and for the rest of this series i won't be setting up my aces workflow here in the project settings but here on the color page using resolve's built-in open effects plugin for asus transforms the end results are going to be identical but doing things this way is going to allow us to get a better more explicit understanding of what's going on under the hood of an asus color pipeline so let's dive in i'm going to go over here to my open effects tab and i'm going to spotlight for aces to pull up my aces transform and i'm going to drop this onto an empty node and we're going to begin by creating the simplest possible form of color management that we can in aces or any other system i'm going to set my input transform drop down menu here to match the color space of my source material which in this case is alexa all of my material in this timeline is alexa with the exception of this one shot shot number 13 which we're going to discuss in a moment so drop down menu for input transform is going to be set to alexa and under my output transform drop down i need to match the color space of the display that i'm mastering on most of the time that's going to be rec 709 and that's the case here so i'm going to select rex 709 and you can see when i go full screen here this may not be all that i creatively want out of my image but i've now got a normalized image it looks much more correct for my display than it did a moment ago here in its camera log state so this is the simplest possible form of color management that we can do in aces or in any other color management workflow where we set up one transform from our camera color space into our display color space and from here we would simply do all of our grading off to the left of this transform and things would work the exact same way for every shot in this timeline i would simply paste this same transform and do my grading off to the left now let's return to shot number 13 which i mentioned a moment ago shot number 13 is the one shot where this method won't work because the input color space is in fact not alexa if i turn this off for a moment we can see that we already have a pretty normalized image which tells me that this material is actually already rec 709 so instead of alexa for my input setting i need to select rec 709 and as long as i spot this and i alter my aces transform accordingly i should be good to go to do all my grading off to the left of whatever my final output transform may be but this brings us to an interesting quandary for any timeline where we have more than one type of camera in play and that's that when i go off to the left of this final output transform my controls and my adjustments are going to be very different between a rec 709 shot like this compared to an alexa shot like this because remember if we think about what my effective sort of working color space is in these two examples here it's area log c because that is the color space of my original material and i'm doing my grading prior to making any transformation of it whereas here on shot number 13 my working space is actually rec 709 because once again i'm doing my grading in the original color space of the image that was provided so my response and the behavior of my controls and the way that things like luts and looks act on these different types of material is going to be quite distinct and it's going to make more work for me when i go to try to match things up and this is why the aces pipeline provides for an intermediate color space which allows us to map everything into one common color space for grading prior to our final output to our display color space so let's get a look at how that plays out let's go over to shot number 12 here and i'm actually going to grab a still of what we've already done using just this one transform and i'm now going to reset everything for the moment and let's drop a new asus transform onto node number one i'm once again going to select alexa for my input color space because that's still the original color space of this image but instead of going to my display color space my rec 709 i'm going to go to aces cct which is one of the two intermediate or working color spaces that the aces standard provides for doing color work and we're going to talk more about the difference between those and when you might want to use which later on in this series for now we're going to go to asus cct and i now need to create a second transform because i've successfully mapped myself from camera color space to working color space but i now need to map myself from working color space into display color space so in this case my input transform is going to be aces cct because that's what i transformed the image into here in node number one and my output transform you guessed it is going to be rec 709 so i've now built this sort of color space transform sandwich here inside aces and all of my grading is going to happen here in the middle of these two color space transforms inside of aces we call this initial transform from our camera color space into our working color space our idt or our input device transform and here on the other side this transformation from our working color space to our display color space we call our odt or our output device transform and if you notice when i wipe to this still that i grabbed a moment ago when i only had the single transformation in place my image is identical so there's no visual difference between these two it's simply allowing me to have an intermediate working space which can be consistent regardless of the original color space of my image and now if we go back over here to our rec 709 shot and apply the same idea except here on the input side we set things to rec 709 i now can work in the same color space on this image that came to me in rec 709 as in this image which came to me as alexa so it allows me to unify everything into one color space where my controls and my response are going to be consistent where i can set looks that i can paste across multiple shots regardless of their source format and it generally helps streamline my process and make things a bit easier when i get into grading so this is a really broad overview for you guys of the way these concepts of color space and color management play out inside of aces and we're going to continue in our next video by going a little bit deeper into the way i would actually set this up for practical use and the way i would begin to grade within this pipeline okay if you're still with me you've already got a huge advantage over everyone who decided to skip the boring part and get to the hands-on stuff learning these fundamentals takes a bit of effort and a bit of patience but without them it's simply not possible to use aces effectively in our next video we're going to build on this foundation and look at how we can set up our own aces pipeline from scratch see you then

Channel: Cullen Kelly

Views: 47,743

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Id: v8P3rshGgdM

Length: 11min 18sec (678 seconds)

Published: Mon Mar 22 2021