How To - Dolby Vision

Dolby Vision - How To and Best Practices



What is Dolby Vision

Dolby Vision is a way to dynamically map HDR to different display targets. At its core, the system analyzes your media and transforms it to ranges less than your mastering target, typically SDR 100 nits.

Project Setup

The first step is to license your machine. Once that is in place you need to set up your project. Go into settings and set your CMU(Content Mapping Unit) version. Back in the day, we used an external box, but nowadays the software does it internally. You will also need to set which version. V4 is the current iteration whereas V2.9 is a legacy version that some older TVs use. Finally set your Mastering Display. That is a Sony x300 in my case which is set up for PQ P3 D65 1000 nits.

Baselight Project Setup

Resolve Project Setup

It’s not what you said, it’s your tone

The goal is to make our HDR master look good on an SDR display. To do this we need to tone map our HDR ranges to the corresponding SDR ranges. This is a nonlinear relationship and our shadows mid-tones and highlights will land in the wrong areas if we don’t tone map them first. See below for an example of an SDR image that has not been tone mapped correctly. You can see the highlights are way too hot. Now we could use a curve and shape our image to a discreet master for SDR, but most studios and streamers are requesting a Dolby delivery regardless if a separate SDR grade was made. Plus, Dolby does a pretty decent job of getting you there quickly since the v4 release.

The first step is to analyze your footage. This will result in three values that will set a tone curve, min, max, and average. These values inform the system how to shape the curve to get a reasonable rendering of your HDR master in SDR.

Image courtesy of Dolby

Tone mapping from HDR to SDR

What we are trying to do here is fit 10 pounds of chicken into an 8-pound bag. Something has to give, usually the bones but the goal is to keep as much chicken as you can. Rather than toss data out, we instead compress it. The system calculates the min, max, and average light levels. The idea is to keep your average or the “meat and potatoes” of your shot intact while compressing the top and bottom ranges. The end result is an SDR image that resembles your HDR only flatter.

How a colorist goes about the analysis is just as important as the analysis itself. This is going to get into a religious debate more than a technical one and everything from this point on is my opinion based on my experiences with the tech. Probably not what Dolby would say.

The original design of the system wanted you to analyze every shot independently. The problem with this approach is it can take a consistent grade and make it inconsistent depending on the content. Say you had two shots from the same scene.

One side of the coverage was shooting the character with a blown-out window behind them. The other side shoots into the darker part of the house. Now even though you as a colorist have balanced them to taste, the Dolby analysis will have two very different values for these shots. To get around this, I find it is better to average the analysis for each scene vs doing independent shots. The first colorist I saw work this way was my good friend and mentor Walter Volpatto. He went toe to toe with Dolby because his work was getting QC rejections based on his method. He would analyze only a grey ramp with the d-min and d-max values representing his media and apply that to his entire timeline. His thought process was if it was one transform to HDR it should be one transform down.

Most studio QC operations now accept this approach as valid metadata (Thank you, Wally!) While I agree with his thought process, I tend to work based on one analysis per scene. Resolve has this functionality built in. When I’m working in Baselight I set it up this way and copy the scene averaged analysis to every shot in preparation for the trim.

Scene average analysis in Baselight.

Setting the tone

Now that your analysis is complete it’s time to trim. First, you need to set what display output your trim is targeting and the metadata flag for the intended distribution. You can also set any masking that was used so the analysis doesn’t calculate the black letterbox pixels. The most common targets are 709 100nits, P3 48nits, and PQ 108nits. The 709 trim is for SDR home distribution whereas the other two are for theatrical distribution. The reason we want to keep the home video and cinema trims separate is that displays that fall in between two trim targets will be interpolated. You can see that the theatrical 108nit trim is very close to the home video 100nit trim. These two trims will be represented very differently due to the theatrical grade being intended for a dark theater vs home viewing with dim surround lighting conditions. Luckily Dolby recognized this and that is why we have separation of church and state now. The process for completing these trims is the same though, only the target changes.

Trim the fat

Saturation plus lift gamma gain is the name of the game. You also have advanced tools for highlight clipping and mid-tone contrast. Additionally, you have very basic secondary controls to manipulate the hue and saturation of the six vectors.

Baselight Dolby trim controls.

Resolve Dolby trim controls.

These secondary controls are very useful when you have extremely saturated colors that are on the boundaries of your gamut. I hope Dolby releases a way to only target the very saturated color values instead of the whole range of a particular vector, but for now, these controls are all we have.

Mid tone offset

Another tool that affects the analysis data but could be considered a trim is the mid-tone offset. A good way to think about this tool is a manual shifting of what your average is. This slides the curve up or down from the midpoint.

I usually find the base analysis and subsequent standard conversion a little thick for my taste. I start by finding a pleasing trim value that works for a majority of shots. Then I ripple that as a starting place and trim from there until I’m happy with the system’s output. The below before and after shows the standard analysis output vs where I ended up with the trim values engaged.

It’s time to export once you are happy with the trims for all of your needed outputs. This is done by exporting the XML recipes that when paired with your PQ master will create all the derivative versions.

XML

Here are two screenshots of where to find the XML export options in Baselight and Resolve.

Rightclick on your timeline -> timelines - >export -> Dolby XML

Shots View -> Gear Icon ->Export Dolby Vision Metadata… This will open a menu to let you choose your location and set primaries for the file.

The key here is to make sure that you are exporting an XML that reflects your deliverable, not your DSM. For example, I typically export PQ P3 D65 tiffs as the graded master files. These are then taken into Transkoder, placed into a rec 2020 container, and married with the XML to create an IMF. It’s important to export a rec2020 XML instead of a P3 one so that when it is applied to your deliverable it yields the intended results. You can always open your XML in a text editor if you are unsure of your declared primaries. I have included a screen grab of what the XML should look like for the Rec2020 primaries on the left and P3 primaries on right. Always go by the numbers because filenames can lie.

Rec2020 XML vs P3 D65

There is beauty in the simplicity of this system. Studios and streamers love the fact there is only one serviceable master. As a colorist, I love the fact that when there is a QC fix you only need to update one set of files and sometimes the XML. That’s a whole lot better than in the height of the 3D craze where you could have up to 12 different masters and that is not even counting the international versions. I remember finishing Katie Perry’s “Part of Me” in 36 different versions. So in retrospect, Dolby did us all a great service by transmuting all of those versions we used to painstakingly create into one manageable XML sidecar file.

Thanks for reading

I bet in the future these trim passes end up going the way of the 4x3 version. Especially with the fantastic HDR displays available from Samsung, Sony, and LG at continually lower price points. Remember the Dolby system only helps you at home if it is something other than what the media was mastered at. Until then, I hope this helps.

Check out this Dolby PDF for more information and deeper dive into the definition of the various XML levels. As always thanks for reading.

-JD

Questioning Color

I was recently interviewed for an article on the power of color. The questions were very thought-provoking, and some topics I hadn’t thought about in years. I think it’s always a good practice to periodically approach the profession with a kindergarten mindset, ask the important “why’s”, and question or reaffirm first principles.


You can check out the article here and see the complete list of questions and my responses below.

Hopefully, this helps my fellow hue benders out there. Let me know if you disagree with anything in the comments. I always appreciate new ways of looking at things.


  • John Daro, Senior Colourist, Warner Bros

    John Daro is a Lead Digital Intermediate (DI) colourist at Warner Post Production Creative Services, a division of Warner Media. He has supervised the finishing and grading of many feature films, television pilots, commercials, and music videos for clients, including all the major studios, in addition to independent productions.

    Daro started his career at the film lab FotoKem. His first notable achievement was architecting a direct-to-disk dailies pipeline. From that role, he moved on to film scanning-recording and, with the DI process's creation, his current position as a finishing colourist. His past jobs gave him a mastery over colour transforms, and he started to couple those strengths with the art of cinematography. He continued to pioneer post-production techniques, including 3D conversion and the early days of HDR imaging. As a founding team member of their digital film services department, he helped FotoKem achieve its status as one of the premier post houses in the film and television post-production industry.

    In this interview, Daro talks to us about how colour can be used to shape an audience’s interpretation of a film and provides examples of how he’s used colour to help communicate a narrative in the past. 

  • How do you think colour shapes the way audiences perceive film?

    It's funny that you asked how colour shapes the audience's perception because, in a way, the colour process is literally “shaping” what we want you to see and what we don't. At its most basic, colour finishing is the process of highlighting and subduing certain key areas which directs the viewer’s attention to where the filmmakers intended. Before digital colour grading, cinematographers highlighted these key areas through shadow, light, depth of field and lens effects. Photochemical timing changes were limited to colour and density.  Nowadays, the sky's the limit with shapes, articulate roto masks and matte channels. Ultimately, the end goal of all these tools is to make it feel natural and true to the story and highlight key moments necessary for the viewer to absorb the supporting narrative. It's an old cliche, but a picture tells a thousand words. 

  • How have you used colour to communicate with an audience?

    A couple of examples that popped into my mind involve using dynamics to simulate coming out of a bright area. I think I used this technique most effectively in Laika’s The Boxtrolls. When Eggs, the film’s protagonist, came out of the sewer for the first time, we applied a dynamic luminance adjustment to simulate what your eyes would do when adjusting to a bright light coming from the darkness. 

    Another example is Steven Soderbergh's Contagion, where colour choices define geographical location to help the viewer know where they were without needing additional information.  I also used this technique in Natalie Portman’s adaptation of Amos Oz’s A Tale of Love and Darkness. For this film, we were dipping through memories and a fantasy world.  Colour choices defined the real world versus the world inside the character’s head.

  • Can you talk us through your involvement in choosing and implementing a colour palette for a specific scene/film?

    So many of these decisions are decided upfront through lighting, production design and wardrobe. It's always a pleasure to be brought in on a project early enough to have been part of those conversations and understand the motivation behind the choices. I feel there's great value for everybody to be on the same page and know how specific colours on the set will render in the final output.

    Look development can have many muses. A style guide, concept art and a reference deck are great tools. I like to start by picking two or three key colours that are important to the story, symbolize a character, or represent a message. Then the objective is to find the best way to shift and enhance to make a split complementary palette. Contrast and simplicity are at the heart of the finest design in my opinion.

  • Do you think colour is the backbone of emotion in film?

    I don't think so, no. I think sound is. Smell would be even more evocative, but luckily for the Jackass movies, smell-o-vision didn't catch on!

    I prefer to grade with the latest mix. It's the sum of all the parts that make a great cinematic symphony. Colour and sound must be playing in concert, similar in tone or in contrast but always together.

    I think that kind of sensory feeling might be ingrained in our DNA. Whenever I hear the opening to Peter and the Wolf, I visualize spring greens. It doesn't work the other way, however. I don't hear Peter and the Wolf every time I see green. Colour must be taken in context. Green can make you feel safe and calm like a lush field of grass blowing in the wind does. At the same time, it can evoke feelings of jealousy or sickness. It all depends on context and the motivation behind the story being told.

  • How do you know when a specific colour scheme does or doesn’t work?

    There are a few academic reasons I could give you. For example, certain colours clash with other colours. Certain colour harmonies are not particularly pretty, but that doesn't mean that you can't use those mismatches. Especially if what you're going for is to make the viewer uncomfortable or uneasy. Colour is subjective; balance is not. 

    Ultimately, the real answer is feeling it in your gut. You know when it’s right. I have an internal rule when taking my passes. The reel is done when I can watch it down and have less than three tweaks to make. You are never really finished. Most often, you just run out of time.

  • How do you work with the director and cinematographer to achieve a specific look in a film?

    I first watch a rough cut or read the script and get an idea of the story. Next, I take camera tests and start to build a basic look. The goal with this V1 transform is to find something that works for the cinematographer and gets them repeated results in different lighting conditions. Obviously, it should also have an aesthetically pleasing visual component. It's important when building a look to ensure that the camera still behaves as expected regarding sensitivity and dynamic range. You don’t want to bake anything that could hamper the original photography. Essentially, make sure mid-grey still maps to mid-grey. 

    Once we have dailies, the process begins again, where I might have a V2, V3, or V4 version of the look that we're going for. I put those in a still gallery on a server for remote viewing, and we constantly update the conversation forum page with feedback from the creatives. I maintain before and afters of all versions to ensure we improve and never go backwards creatively. The last step is to ensure that the look works for the story once the film is assembled. Tweaks are made to the show look and certain scenes get special treatments for effect. 

    CDLs are a vital part of this process as well. Grading your dailies is very important for ensuring that there are no surprises when everyone gets to the DI theatre. I've had past experiences where producers see something that has the final grade, but it's too far of a departure from what the look was in editorial. To combat this reaction, we always want to ensure that the look is consistently maintained from the first shot out of the camera through to the final finish.

  • How can colour set the tone for a scene? 

    To set the tone, it's all about warmer, colder, brighter, or darker. As I've already touched on, it's really important to pick a few colours that you want to enhance and then let the background support that enhancement, whether through a complimentary value or making it recede. They're also the obvious washes that you can do. For example, if you make a scene very red, the warmth invokes a sense of romance or love. It can also yield a literal hot vibe. Something very cold, very desaturated invokes a sense of bleakness or a dystopian feeling. Magenta's a weird one because it can be warm and cold at the same time. Depends on the context and how it's used. Green-yellow also functions similarly. It can seem sickly and off, but it can also be romantic and warm, depending on what side of the hue you're on. I don't know where these generalities came from, but they're almost universal at this point. My gut is that human evolution has something to do with it. I think the responses to these colours helped us survive at some point. When I say it’s in our DNA, I do mean just that.

  • What technical difficulties do you come across with undertaking this critical part of film production?

    You can avoid many technical difficulties by ensuring you’re doing no harm to your pixels. The most important thing is that you have a colour-managed pipeline, in that you’re never working on what the film looks like, but rather what the film was captured as. Make sure you’re always working in a photon real-world scene-referred way. At that point, the displays don’t matter as much. They simply target what you’re trying to hit. They can always be adjusted after the fact if there are technical concerns. I always work with soft display-referred transforms that gradually roll off your highs and also have a nice toe in the black. This generally helps cut down on the number of technical issues. 

    Past that, it's all about keeping your eye on the scopes and ensuring there are no technical glitches in the actual capture or renders like quantization, dead pixels, hits or bad frames. All it takes is an eye for detail and a great QC department.

  • How does your role as colourist differ when working on animation compared with live action films? 

    At the core, the two are very similar. The same principles that make a strong image still hold true regardless of how the image was created. Modern render engines are very good at doing what light does. So much so that a lot of DoP buddies of mine are pre-vising lighting setups virtually.

    Nowadays, that line is being blurred even further, where some films can be comprised of mostly VFX shots. Many of these setups, especially with the advent of digi doubles, are not very different from a fully animated picture.

    Now, if we’re defining a “live-action” shot as being something captured with a camera, and no further manipulation, then the biggest difference comes from the workflow. For example, if you take a live-action setup that has been shot with clouds and maybe some inconsistent lighting situations, your first step is technical colour correction just to balance the shots together. You don't have this problem with animation, but you do have a similar situation where you might have many artists working on the same scene. This can sometimes lead to slight inconsistencies that must be smoothed out.

    A huge advantage of CG-originated shots is that they tend to have advanced matte channels. These could be as simple as a matte for the main character or as complicated as depth or normals. These additional tools allow for more complex grades but also increase the time that you spend on each shot.

  • Can you tell us about your grading suite? What could you not be without while at work?

    My grading suite looks like a hot mess. Imagine the Great Wall of monitors. I have two x300s, and two GUI monitors for Baselight, one extra wide LG for what I call my Swiss Army box and an admin computer. The most important display is my Christie 4k projector. I also have an LG C2 to simulate a consumer experience.

    The most important machine in my tool set is the Swiss Army box. Essentially, it's a super micro chassis with four a6000s that has every single piece of post-production software that has ever been useful. I also use this box for coding and the development of my own in-house tools. I would consider this machine mission-critical. Second to that, the next most important piece of gear would be an external scope. Your eyes can lie to you, but scopes never do. Software scopes have made huge advancements in recent years. I can't say I use the external one every day, but when you need one, there really isn't a substitute.

  • How does Baselight aid your role as a colourist?

    There's a lot of great software out there and I always say use the right tool for the right job. For most of my jobs, that ends up being Baselight. The reasons are straightforward. Firstly, the colour science in the machine is second to none. Next, I appreciate the simplicity of the interface. When colouring long form, most of what you're doing is manipulating groups of many shots. Baselight makes this very easy to do. The other thing I can't live without is how Baselight organises and categorises. When you get towards the end of the project, things get hectic, and it's very nice to be able to sort and view in any way that a project demands. Often this has to do with missing visual effects or work I need to get to after the session. I use categories and marks so that I always know what the status of a scene is at any given time. This organisation also aids in communication. I can always keep post supervisors up to date with reports. Additionally, my in-house team always knows what needs to be done and what is already completed based on the organisation that we have put in place. I've always felt that Baselight was built by people who do the job of colour – not by committees or nonpracticing theoreticians. 

  • What are you working on now/next?

    I’m currently finishing a docuseries directed by Allen Hughes for FX about Tupac Shakur’s life and relationship with his mother called Dear Mama. The interviews have an exciting cognac look that I can’t wait to share. The first part premiered at the Toronto International Film Festival and was very well received.

    Later this month, I will be finishing a feature called Sweetwater. It’s about the story of the first black NBA player, Nat “Sweetwater” Clifton. It is a period piece, so a lot of fun in the colour department. We contemplated a black-and-white double X look for the show but ultimately landed on a derivative of an Ektachrome simulation that I had built a while ago. It has a super cool look if I do say so myself.

    We are also supporting pre-production and dailies on A Gun on Second Street. This show is shooting on film, which is always pleasurable and exciting.  The look for the show is a straightforward Kodak film vibe, expertly lensed by Leo Hinstin.

    While we are on the topic of film shows, I’m also supervising the remastering of Superman II (yes, both cuts.) This will be released in early 2023 just in time to get people excited about Michael Shannon’s General Zod in The Flash. Kneel before Zod!

    Additionally, my team and I will return to animation early next year for an upcoming Netflix feature. More on that later at www.johndaro.com.