The Offset Podcast EP024: Calibration

We hope you had a great holiday season! The Offset Podcast is back for Season 2. We publish an episode every two weeks, and for Season 2 (2025), we’re excited to discuss a wide range of exciting topics.  

In this episode, we explore a subject that should be important to everyone who cares about image quality and accuracy—calibration. While this episode is not encyclopedic, it should give you a high-level overview of modern calibration.

Topics covered in this episode include:

• The importance of calibration & why calibration = the truth
• Using color bars to set a monitor baseline isn’t calibration 
• How standards guide calibration
• Calibration and monitor perfection is unattainable - the goal is to eliminate visual deviations from reference as much as possible. 
• Understanding the parts of a closed-loop calibration system
• Colorimeters
• Spectroradiometers
• Creating display-specific offset matrices for a colorimeter with a spectroradiometer 
• Pattern generators
• Pattern/Patch size and understanding the basics of loading behavior
• Calibration software 
• Direct device control within calibration software
• Meter placement 
• Challenges of calibrating projectors vs. direct-view monitors
• Understanding what calibration can’t do & recalibration considerations 
• Is auto calibration any good?
• Hiring a professional calibrator 

Thanks for checking out the show!  If you liked this episode please like, subscribe, and share the show with friends and colleagues.

Creators & Guests

Host

Joey D'Anna

Joey is lead colorist and CTO of DC Color. When he’s not in the color suite you’ll usually find him with a wrench in hand working on one of his classic cars or bikes

Host

Robbie Carman

Robbie is the managing colorist and CEO of DC Color. A guitar aficionado who’s never met a piece of gear he didn’t like.

Editor

Stella Yrigoyen

Stella Yrigoyen is an Austin, TX-based video editor specializing in documentary filmmaking. With a B.S. in Radio-Television-Film from UT Austin and over 7 years of editing experience, Stella possesses an in-depth understanding of the post-production pipeline. In the past year, she worked on Austin PBS series like 'Taco Mafia' and 'Chasing the Tide,' served as a Production Assistant on 'Austin City Limits,' and contributed to various post-production roles on other creatively and technically demanding projects.

What is The Offset Podcast?

The Offset Podcast is a semi-monthly (twice a month) podcast hosted by postproduction industry stalwarts Robbie Carman & Joey D’Anna - we’re professional colorists, educators, and polymaths in video postproduction and color. We’ve been told our detailed, informative, and easy-to-follow explanations of even the most technical subjects have helped people at all levels to improve their workflows, tackle their technical/creative problems, and even improve their approaches to business & client communication.

Geared towards postproduction industry professionals each episode feels like catching up with valued peers and is the perfect length for the average commute, lunch break, or to keep you company while you work.

01:00:00:11 - 01:00:14:13
Robbie
If you're somebody that cares about image quality, then you should care about calibration. And that's what we're talking about this week on The Offset Podcast. Stay tuned.

01:00:14:15 - 01:00:33:04
Joey
This podcast is sponsored by Flanders Scientific leaders in color accurate display solutions for professional video. Whether you're a colorist, an editor, a DIT, or a broadcast engineer, Flanders Scientific has a professional display solution to meet your needs. Learn more at Flanders scientific.com.

01:00:33:06 - 01:00:57:14
Robbie
Welcome back to another episode of The Offset Podcast. I'm Robbie Carman and with me, as always, is my partner in crime, Joey D’Anna. Hey, Joey. How are you, man? Hey, and Joey, this week, let's talk a little bit about calibration. And actually, we got several inquiries from on our, submission form on offset podcast.com, where people are like, hey, could you talk a little bit more about calibration?

01:00:57:16 - 01:01:26:10
Robbie
I was like, yeah, sure. I love to talk about calibration. And to me, the calibration, we could probably do five, six, seven episodes on it because there are a lot of parts to the calibration process, that are nuanced, have a lot of detail. But as we do on these kind of big, big, kind of big concept episodes, our goal is to kind of just break it down into a better understanding of the process and the tools and the vocab.

01:01:26:14 - 01:01:45:19
Robbie
But by no means is this, you know, this next 45 minutes to an hour a definitive guide to monitor calibration. I just don't want anybody get the wrong idea. We are not. You and I are not professional collaborators. We calibration recalibrate because it's of interest to us. And partially out of necessity as our life of as professional colorist.

01:01:46:00 - 01:02:00:01
Robbie
But I just want to be clear with everybody. There are probably some things that we'll probably say in this episode that could be a little more explanatory, or maybe have some nuance to them. Don't yell. Yeah. Don't yell at us. We're just trying to give people kind of,

01:02:00:03 - 01:02:02:08
Joey
that’s what the comments are for exactly.

01:02:02:08 - 01:02:28:14
Robbie
The big picture here. And if you do have something specific, that is in regards to calibration, feel free to add it into the comments on YouTube or always, you can email us by, on over to the [e-mail]. So with that said, Joey, let's talk about monitor calibration. And the first thing I always say in this conversation is proper calibration and monitor setup equals the truth.

01:02:28:16 - 01:02:54:21
Robbie
Right. Our goal as far as professional image makers, if you will, is that every time I lay my set eyeballs on a monitor, I want to be able to go. That is reality. That is the truth, right? And without that, like, what am I really doing here? Right. I'm just sort of guessing that something that is, you know, kind of, you know, faking the truth at that point.

01:02:54:23 - 01:03:17:18
Robbie
It is, but more so than any other thing that we do as colorist editors, you know, DP's or anybody else who cares about images is that we want to make sure that what we're doing is the truth and is actually representative of what the ones and zeros on a hard drive and how they are actually displayed correctly so we can see them and make creative decisions about it.

01:03:17:18 - 01:03:23:22
Robbie
It's that simple to me. Calibration equals truth. You think about it in other, other ways. Or is that kind of summing up?

01:03:24:00 - 01:04:01:09
Joey
Yeah, calibration is always the very important, especially in the color world. You know, you don't need that full level of truth necessarily for editorial especially like offline editorial. It's nice. It's nice to get close to it. Right. But when we're talking about the last final finishing stages of a project and it needs to look its best, be output and encoded in a way that is completely representative of an accurate description of the creative vision of the project.

01:04:01:14 - 01:04:21:20
Joey
Now, this has always been exceedingly important these days. Now that there's so many different monitor technologies out in the world, and there's so many different types and formats of both SDR and HDR delivery, it is so much more important now than it's ever been in the past.

01:04:21:21 - 01:04:41:02
Robbie
You used to be able to go pretty much anywhere in the world to a post-production facility, and chances are you'd be looking at a Sony CRT that was one of 2 or 3 models sitting on a table, and you could be relatively assured that within a slight amount of variance, what you saw at one place was kind of the way you saw the other place.

01:04:41:02 - 01:05:06:18
Robbie
Now, of course, that's not always true. People could set these things up properly, but at least we were with similar technologies. You know, driving, driving the picture if you want. I think that's your point, is that now we have LCD, OLED, SDR, HDR, you know, Rec 2020, Rec 79, whatever it is, there's more variables at play that impact, image accuracy now than at any other point, prior in this industry.

01:05:06:19 - 01:05:20:09
Joey
Yeah. So if we want to do the right thing for our clients. Yeah, we need to be really, really sure that what we're looking at and what we're evaluating is accurate to the standard in which we are delivering.

01:05:20:11 - 01:05:45:04
Robbie
Yep. So I think, let's start out this conversation now that we've kind of, you know, said why we want to do it. I think my first exposure to kind of the general idea of, calibration was probably, if I'm guessing was probably similar to yours. And that was a big, Sony BVM CRT sitting in a room somewhere and an engineer at the facility that you were working at came in and said, get out of the way.

01:05:45:06 - 01:06:06:19
Robbie
And what do they do? They brought up, some color bars. Right. And with these knobs in the front of the display. Right. You know, I'm talking about the brightness, phase, you know, contrast. They would use a set of color bars to air quotes here, calibrate the monitor. Right. This is we now know, of course, these days that's not really calibration.

01:06:07:01 - 01:06:28:11
Robbie
That's kind of like baseline set up. But that was kind of my first exposure to understanding. Kind of like oh okay. Well we want this white plush pattern to be kind of this white because that represents my peak luminance output. Right. Or we want, you know, these colors not to bleed into each other because when they do we have hue shift and so on and so forth.

01:06:28:11 - 01:06:30:06
Robbie
Did you have a a similar experience? Yeah.

01:06:30:06 - 01:06:45:14
Joey
And it's actually it's interesting because what we know, all of us simply color bars. Yeah. Or actually a very, very smart, well developed test pattern specifically for this purpose. And the guys that invented bars won an Emmy for it.

01:06:45:16 - 01:06:47:17
Robbie
Yeah, very justifiably so.

01:06:47:21 - 01:07:13:08
Joey
Now, like you said, this was during the time of CRT. So most of the technology was the same. You had an electron beam, exciting phosphors that lit up as a color. Right? Those phosphors were generally chemically the same across all of the the professional world. That's why you had simply phosphors, whether you were in a Sony monitor and he Kagami monitor or Panasonic monitor.

01:07:13:10 - 01:07:33:17
Joey
They all use simply compliant phosphors. So red was red, green was green, blue was blue. But you had to do what you just said. Set up the monitor. And as I love to dive into an old man screaming at kids to get off their lawn, there's a couple interesting things I just want to mention about how that worked.

01:07:33:17 - 01:07:38:16
Joey
With color bars. You had three black bars or near black bars on the bottom right.

01:07:38:18 - 01:07:42:02
Robbie
Also, one of those also known as Pleasures Cluj.

01:07:42:04 - 01:08:05:05
Joey
Yeah, those bars were designed so one was below black, one was pure black, one was slightly above black. So you would adjust the black level of the monitor, crank it all the way up until you saw three, back it down until the first one went away. So that's below black. The second one turned exactly black and then you could just barely see the third one.

01:08:05:07 - 01:08:24:10
Joey
This is the very first example of having that essential truth, because I actually, I swear to God, this actually happened within the past couple of years. I had an editor that I was working with tell me that the grade was completely wrong because he pulled up color bars and he knew his monitor was right because he could see all three gray bars on the bottom.

01:08:24:14 - 01:08:47:19
Joey
Well, obviously his monitor was set up completely wrong. So what he was looking at was not the truth. And what I was looking at was the truth. Right? So these monitors also had what was common at the time, a blue only button, which would only enable the blue part of the guns to light up all the color bars.

01:08:47:19 - 01:09:12:19
Joey
And then you could adjust the saturation control and the tint control of the monitor. Because the color components there were a couple that they were different colors, but they had the exact same amount of blue. So and we would even, you know, way back in the day before we had any notion of calibrating home displays, I would have a DVD with color bars encoded on it and a little calibrated blue photography filter.

01:09:12:23 - 01:09:36:12
Joey
You could look through that and essentially do that blue only adjustment on consumer devices. So again, just like you said, we were using color bars and known constants. The the amount of blue, the level of black versus gray to adjust these monitors. So they were all representative, as close as we could get them to the truth of what our signal was.

01:09:36:12 - 01:10:00:20
Robbie
But here's the big problem with this, right, is that in principle, it all sounds like we should get to a more or less same place with whatever time. You know, every time we do that, the problem is, is that it is not analytical whatsoever. It is using it's using eyeballs within an environment to make a decision. And your eyeballs lie to you, or the combination your eyeballs in your brain.

01:10:01:01 - 01:10:22:18
Robbie
Why do you all the time your your environment impacts greatly how those about analysis of your brain is working. So, you know, you walk in one day and go, oh well yeah, those flush patterns are fine. Walk in the next day, raise the black level, raise the contrast. Because it looked a little different and it got to the, you know, the joke of, you know, what does NTSC stand for, right.

01:10:22:20 - 01:10:24:20
Robbie
Not the same color twice or whatever. Something like.

01:10:24:20 - 01:10:26:06
Joey
That. Right. Never twice the same color.

01:10:26:06 - 01:10:48:15
Robbie
Right. Exactly. So, you know, I still think that sort of initial baseline set up, like that, it's great. Like, you want to make sure your monitor is kind of within the general range, but these days color bars. Yeah. Not something that we really want to screw with on a serious level for any meaningful calibration. It just it's just good to have that kind of perspective of, of what we're about to talk about.

01:10:48:15 - 01:11:00:18
Joey
So now I will say this color bars can be very useful still to this day to verify, calibrate and adjust signal pathways. I go versus data range levels 120 versus 700.

01:11:00:19 - 01:11:02:07
Robbie
But they're not they're not going to show you.

01:11:02:07 - 01:11:07:07
Joey
The bars go matter for making sure your SDI pathways are correct.

01:11:07:07 - 01:11:28:15
Robbie
Well they're never going to show you is the actor is the the cyan in this sky. Is that the cyan that it's supposed to be? Right. It's never going to wreck. Never going to show you that. So okay. So with that out of the way, let's talk about kind of the idea of modern calibration and the the first thing I think we need before we talk about the parts of it in the tool sets, I think we just need to talk about the kind of the idea of standards.

01:11:28:15 - 01:12:03:20
Robbie
Right. So over, over the past 20 years or so, probably a little longer. Standard bodies like the ITU simply, etc. have all kind of come up with standards that we all know pretty well these days. Right? So, you know, rec 7 or 9 or 7 or 9, 20, 23 D 65, etc., one of one of, if not the most important calibration goal is making sure that your display adheres to whatever that particular standard is for a lot of different metrics, light output, how much, how intense.

01:12:03:20 - 01:12:22:03
Robbie
You know, how bright the monitor is, the gamut that it's hitting in terms of primaries, and secondaries in that monitor. And then also, just how much does it deviate on any given color from what a reference standard is for that particular color I mentioned, the sky blue could be skin tone, it could be whatever. Right.

01:12:22:04 - 01:12:43:18
Robbie
So every time that we're calibrating, we're trying to calibrate to a reference standard and whatever that standard that you decide to use is, is your choice. Like again, 7 or 9, 20, 20, P3, whatever. But we're trying to hit that standard. And everything that we do in calibration is based on how close can we get there. And that is a really important thing to say right off the top.

01:12:43:20 - 01:13:20:04
Robbie
You will never Robby Furman, get to a place where you have a perfect display. The perfect display does not exist. Let me say that again. The perfect display does not exist. And at a certain point, as you go down this path and getting more calibration, I'm saying this as a reminder for myself. Sometimes all you're doing is just creating slightly prettier graphs with zero impact on actual use, and you just got to kind of keep that in mind that this can be, a marathon chase if you're trying to chase perfection because it doesn't exist.

01:13:20:04 - 01:13:21:10
Robbie
All right. So I just had to get that out. Yeah.

01:13:21:11 - 01:13:47:21
Joey
And, you know, it's important to know these standards. The reason why we call it reference, right, is because we are literally the standards basically explicitly define what input values at the signal side come out of the display as wavelengths and intensity of light. So we're connecting the virtual world to the actual physical world of light. It's documented what it should be.

01:13:47:23 - 01:13:54:08
Joey
The goal of the calibration is to get the actual reality of our system as close to that standard as possible.

01:13:54:08 - 01:14:12:11
Robbie
Yeah. And and we'll see that as well. We'll dive into this in a little bit. But we'll you just so you know, that standardization that you're talking about does there's values to it. Right. Z y coordinates right where x small x and x and small y are chromaticity coordinates. And where big y is our our, our intensity, our luma.

01:14:12:11 - 01:14:31:04
Robbie
Right. How how bright something is, is coming up for display. So you know that if you just went to, whatever, you know, a specific yellow, that specific yellow should have this x, y, y value to it that, you know, and be able to replicate that. Well, and, you know, in RGB terms, you see that as a RGB triplet.

01:14:31:08 - 01:14:53:19
Robbie
But the idea is that that is a known quantity. And if we deviate from there, we have some deviation with the goal of just trying to get that deviation as low as possible. All right. Now that we've gotten that out of the way, let's talk about the parts of a calibration system. And I should be clear. These days we are primarily talking about the concept of closed loop calibration.

01:14:53:19 - 01:15:16:15
Robbie
Right. Closed loop calibration, meaning that all of the various parts are talking to one another. Right. The meter that you're using is talking to the pattern generator, and the pattern generator and the meter are talking to your calibration software. This is different than open loop calibration, where you might take a reading of something on a display and then manually advance to another slide.

01:15:16:20 - 01:15:33:14
Robbie
Take another reading set, and so forth. These days, pretty much every calibration, you know, every setup that you're going to do is going to be a closed loop setup where everything is talking to each other and probably the most important piece of that closed loop setup is going to be the meter or what some people call the probe.

01:15:33:14 - 01:15:57:22
Robbie
I don't like to use the word probe because it reminds me of alien abductions or something. So I tend to use meter, and these fall into two, general categories, and that is, a colorimeter and a spectroradiometer. Right. And I just like to say spectrometry, I'm going to really fast because it makes me sound, super smart, but these are, two common, meters that are used but kind of operate differently.

01:15:57:22 - 01:16:22:18
Robbie
And they're they serve sort of different purposes, and they're pretty easy to understand. A colorimeter is going to be, off most often times, really, all the time is going to be a cheaper device. And colorimeter is work by having, RGB color filters, that incoming light gets filtered through before it hits a sensor. That sensor outputs, those x, y, y coordinates that I mentioned earlier, color emitters.

01:16:22:18 - 01:16:43:15
Robbie
Their benefit is that they can read data exceptionally fast coming off the screen. So you can have it every quarter of a second. Take a reading and it can go through thousands of patterns really fast. They're also very accurate at low light levels. Right. They can read into the dark pretty well. Their downside is that they are filter based.

01:16:43:15 - 01:16:49:03
Robbie
So the quality of those filters are going to matter dramatically. The ice.

01:16:49:05 - 01:16:49:15
Joey
Age.

01:16:49:19 - 01:16:57:08
Robbie
The age of those filters, their isolation from the environment is going to, really factor into how good they are.

01:16:57:09 - 01:17:04:16
Joey
Essentially, a colorimeter is a monochromatic level sensor with red green and blue filters in front of it, right.

01:17:04:18 - 01:17:26:00
Robbie
That's perfect way of saying it. But, you know, it's it's interesting because people and I want to pick on any particular product, but people go out and go, oh, well, I bought a colorimeter that cost me 100 bucks and I'm still not getting great results. And with those really entry level color emitters, what you're really the downside of it is that the filters are just crap, right?

01:17:26:00 - 01:17:38:12
Robbie
You could take the same reading 30 times in a row and get 30 wildly different results from it because, oh, guess what? It's been sitting in front of the display and got hot for, an extra couple minutes. And now, you know, it's.

01:17:38:12 - 01:17:44:17
Joey
Similar to what you started out with, is they don't know the actual reality, right? They don't know the truth.

01:17:44:19 - 01:18:06:05
Robbie
Let me hold on let me get back to that in one second. Right. So color emitters use filtered rays to kind of get their data, their benefits for going fast, reading the dark, but their accuracy can suffer as we just mentioned. So the other type of meter is a spectroradiometer or a spectrum for short. So a spectrum actually measures the actual wavelength.

01:18:06:05 - 01:18:26:04
Robbie
Length of incoming light basically gets split in a prism and goes right to the sensor. There are no color filters involved with that. Right. And and because of that they are much, much, much, much more accurate than a color emitter right off the box. I'm gonna put a little asterix of that, that I'll come back to that in a second.

01:18:26:06 - 01:18:48:22
Robbie
But, a good spectra can read specific wavelengths very accurately. And a spectrum is great for accuracy, but it's terrible for speed. Spectral will take a very long time to read something, and it's really, really bad. The dark. The more dark something gets a little light, has no chance of reading low lights accurately, and it will take a long time.

01:18:48:22 - 01:19:17:12
Robbie
So we have a colorimeter. That's good. It's super fast and low light, but kind of sucks for color accuracy. And then we have a spectrum that's really, really, really accurate. But is, you know, terrible for speed. How do we kind of combine the two? Well, in this case, in most calibration workflows, people use Spectroradiometer or spectrum to create an initial profile of, a monitor, by using red, green and blue, RGB and white pattern.

01:19:17:12 - 01:19:44:15
Robbie
So there's four patterns red, green, blue and white. They measure those of the spectrum, they measure those with the colorimeter. And whatever the difference between the reference image, the spectra, and the colorimeter, that creates what's called an offset matrix, and that offset matrix can get loaded on to the colorimeter. So the Colorimeter essentially sees like the spectra does, but now can do so much faster and into much darker light.

01:19:44:15 - 01:20:07:14
Robbie
So most professional calibration workflows, you're going to see collaborators with two meters, you're going to see them with the spectrum, and you're going to see them with the Colorimeter. They'll use the spectrum to profile the colorimeter. So it's more accurate. And then they might use the spectra as a final QC step after the the, the calibration is done just to get a quick, accurate view of what the monitor is doing right.

01:20:07:16 - 01:20:32:00
Robbie
One more thing about this. Not all spectrums are created equal either. Right. And this is kind of an interesting thing. If you start looking in the spectrums, you'll see that they can get really expensive really quick, like 13, 15, 20 grand, 40 grand, etc.. Right? One of the major differences with when you're looking at Spectroradiometer is the resolution of the wavelength that it can differentiate.

01:20:32:00 - 01:20:48:01
Robbie
The resolution, is noted in nanometers, right? So a ten nanometer spectrum is not as spectrally narrow as a, say, a two meter, a two nanometer, spectrum. And why that's important is because as.

01:20:48:01 - 01:20:49:22
Joey
We go, spectra wouldn't be very good.

01:20:50:00 - 01:21:14:00
Robbie
Meter would not be very good about, two nanometers. Why this is important is because as displays like OLEDs and kudo LEDs and all that kind of stuff have gotten more popular, their wipe output, if you look at it as on a, on a spectral, power distribution graph, they actually are very spiky in certain places. You might get the blue channel, you know, being very pointy and spiky or the red channel or whatever.

01:21:14:02 - 01:21:37:19
Robbie
The higher resolution spectra lets you kind of zoom in on that spiciness and get more levels of gradation of accuracy, when you're using the higher resolution spectra. So, to sum that up, Colorimeter is fast, good, and dark spectra is, more expensive. But slow. Use the two together so you can get your fast colorimeter to be just as accurate as your spectra.

01:21:37:22 - 01:22:13:20
Joey
Yeah, you calibrate the colorimeter with the spectra, and that's how you can kind of even use, we wouldn't recommend using a really cheap colorimeter, but you can make not super expensive color emitters kind of punch above their weight by calibrating them and generating the offset matrix with a spectra. Now, if you buy a very expensive colorimeter, it probably has really high end filters that are known to last a long time with little change, and has been very accurately profiled at the factory by a spectral radio.

01:22:13:22 - 01:22:34:23
Robbie
Yeah, and those offsets that I mentioned, just to be clear, and we'll talk about calibration software in a second, but every calibration software tool out there will let you load via software, will let you load a matrix. Right. We'll let you say, okay. All right. Today I am using a, you know, shrill lead. So I'm going to load that matrix and software some color emitters.

01:22:34:23 - 01:23:00:20
Robbie
I actually have memory on the meter itself to where you can store that matrix on the meter. Instead of having to use software and then switch between whatever, when you're using. But it's really, really important to make make mention of this. If you do decide to use a generic offset for your colorimeter because you don't have access to a spectrum, keep in mind that's kind of like a compromise.

01:23:00:20 - 01:23:28:18
Robbie
Like, hey, I'm just trying to use this general idea of this backlight technology. It is always better, always better to profile or to sort of, you know, kind of calibrate, if you will, that, that colorimeter with a spectral using the actual display that you are going to calibrate because there are very, very minor differences, you know, between display even there, they're using the same backlight technology.

01:23:28:20 - 01:23:38:03
Joey
And even temperature, humidity, etc.. All very, very, very minor factors, but still factors.

01:23:38:05 - 01:23:59:15
Robbie
Yeah. So one of the cool things that if you don't want to spend thousands and thousands of dollars, you could get a mid-level colorimeter like say, you know, 5 or 6, $700 colorimeter that's pretty good. But not awesome. Filters rent a spectral borrow spectral profile for that, use it for that particular case, and then save that matrix to load it in software to load it on the meter directly.

01:23:59:21 - 01:24:19:03
Robbie
And then you have a display specific offset that you can load on your colorimeter at any time. That helps it be much more accurate. Right? So that's it's a it's a pretty cool, pretty cool way of working. So that's meters. And how and how the two types and kind of how they work. We again we explain sort of the dangers of those cheaper color emitters.

01:24:19:05 - 01:24:39:16
Robbie
In general, they're not very stable, but they're going to be better if you can use a proper offset matrix for them to be display accurate or more display accurate for the backlight technology that you're using. And better yet, for the specific display you're using. So the other piece of hardware that we have in that equation, so after we have meters is a pattern generator.

01:24:39:19 - 01:25:06:09
Robbie
Right. Pattern generator as its name implies, produces patterns. Patterns of what? Well, they can produce different patterns, a lot of different things. But in a calibration workflow, what they're doing is they're outputting very specific RGB triplet values for specific colors. Right. So if you decide to go some peachy color, I don't know. I don't know what the values are for my head, but let's just say you have something that is, you know, an eight bit.

01:25:06:09 - 01:25:30:23
Robbie
It's 222, 238 and 211 who knows what that color is, but let's just say that it is. Well, that's what the pattern generator's outputting that specific value of that specific color. In that specific, that, you know, with that specific accuracy that's outputting pattern generators, can output different RGB triple values and they can output different bit depths.

01:25:30:23 - 01:25:49:13
Robbie
They can also output different resolutions. The general idea is that you want your pattern generator to be set up to where it's outputting to how you are displaying. So if you have a you display, have an output, you FD. If you have a ten bit display, you're having an output ten bit, etc. pattern generators can come in a couple different forms.

01:25:49:15 - 01:26:15:11
Robbie
They can come in small little handheld devices that you connect via HDMI or SDI. But we can also use software pattern generators. Guess what? Resolve. Resolve can be a pattern generator. It integrates nicely with, portrait displays Calman as well as, color space. And it can, those app, those calibration applications can take control of resolve and have it output as a pattern generator as well.

01:26:15:13 - 01:26:44:07
Joey
One important thing to think about when you're using pattern generator and setting up your calibration workflow, various displays react differently to different sizes of patterns, so you can go full screen with your pattern generation. That would be fine on, say, a CRT, but most LCDs, modern OLED, etc. might behave differently with a full frame of color versus a small enough patch to where your meter sees it.

01:26:44:11 - 01:26:55:09
Joey
So just be very cognizant of the fact that you probably don't want your pattern generator to be outputting a full frame image. You want it to be outputting a small square where you're going to be probing with your colorimeter.

01:26:55:11 - 01:27:21:06
Robbie
And the technical term for that is loading behavior, right where certain space. And this is more common in OLED type displays where when you get a larger and larger percentage of screen, the monitor actually can't produce the brightness that it potentially should at that level of brightness. So if you had a full screen red pattern, it's not going to be able to produce that at, say, whatever the value is for it.

01:27:21:11 - 01:27:44:20
Robbie
So you have to reduce that. So the circuitry doesn't automatically limit it. I have found that, you know, depending on the display and, you know, there's all these calibration software is going to have different guides for this kind of thing. Somewhere between five and about 15%, 20% is a good size for that kind of windowed pattern. But definitely check, with your calibration software, because.

01:27:44:20 - 01:27:48:10
Joey
You also don't want a lot of heat buildup during the calibration process as well.

01:27:48:10 - 01:28:07:09
Robbie
And there's there's other parts of that, too, with a pattern generator like you might instead of doing sequential patterns, you might insert a gray field every once in a while to kind of break up, you know, the display, in terms of, you know, burning and other things of that nature as well. So the pattern generator, is producing these values that the meter is reading.

01:28:07:11 - 01:28:31:01
Robbie
Where does that data go to after a pattern is read on the display, what happens to it? Well, that's where it goes to calibration software. And calibration software's goal is it's a couple things. Number one, it's basically be a, database or a recorder for all the values that it's reading off a particular display. It knows what the reference that you're trying to hit is.

01:28:31:05 - 01:29:04:22
Robbie
Right? And after you've got your real world measurement and you got your reference understanding of what those values should be, it can then calculate mathematically what should be going on the difference between those two, and create a calibration lookup table with that LUT can be loaded directly on to the monitor, can be loaded onto a lot box, or any number of places can be loaded in software with the idea that the lookup table is getting your real world measurements to be much more in line with whatever the reference is, right?

01:29:05:00 - 01:29:28:14
Robbie
And that calibration software can do that in a number of different ways. You can do patterns that, you know, reading display that's 10,000 patterns. Do what, you know, you know, five pattern readout. There are a lot of different use case scenarios, but that's essentially what the calibration software does is records those readings and then calculates the difference between that and standard, and then creates a lookup table of some sort to, load onto your model.

01:29:28:17 - 01:29:49:12
Joey
Yeah. And this is why calibration in LR world is so important. Because you might just say, hey, well, why am I kind of like I match the monitor or even with like the old days, color bars kind of adjust the monitor to where it's right with these kind of overall controls or even more targeted like, oh, adjust the red gain, the blue gain, the green gain, kind of dial it in.

01:29:49:12 - 01:30:21:21
Joey
Right. Well, those are all basically one dimensional adjustments, right. When you're doing this kind of modern calibration, we're doing it what's called volumetric Li. It actually has a 3D volume to how these values are displayed. Those dimensions are your X and y color coordinates and your brightness. Because the monitor might behave differently for a particular color at certain brightnesses than it does lower or higher brightness is it might, you know, red might track one way, green might track another.

01:30:21:23 - 01:30:39:08
Joey
And by making a full 3D lookup table, the software can actually kind of mold your signal to be right in all the places not right in most of the places, which is what it would be if you conventionally just adjusted kind of gains and biases.

01:30:39:08 - 01:31:09:00
Robbie
Yeah, yeah. And, you know, I think the, the one thing to understand about calibration software and this is a blanket statement that maybe I'm the only one, but calibration software to me is kind of an obtuse thing. Right. And I think that's partly because I'm not calibrating every single day I break my meters out, you know, a couple times a year I calibrate, there are levels of nerdiness that you can get to within a calibration workflow that how about it?

01:31:09:01 - 01:31:36:14
Robbie
Be as nerdy as you want, but for baseline calibration, needs that most of us have. It's actually more it's easier than it ever has been before. Portrait displays where their Calman products, color space, display core is an open source, calibration. Platform. There's there's a number of ways to do it. And I use, I use all of them for different things or different measurements or different workflows, but the idea is essentially the same.

01:31:36:14 - 01:31:58:12
Robbie
You measure the display, you calculate the software, calculates the differences between standard and kicks and spits out a lot. Now, if you have a display that doesn't support a lot directly, or you don't have a LUT box or whatever, that doesn't mean that you can't use calibration software. It's just not going to be in a way that is sort of, you know, more or less automatic.

01:31:58:12 - 01:32:04:18
Robbie
You're going to have to go and start adjusting dials on the TV or whatever to kind of get those into play.

01:32:04:20 - 01:32:29:23
Joey
Yeah. And, you know, one of the thing to mention about calibration software is we've thus far only talked about one format, right? Take a model of the display's output, mold it into what is right for a standard. The cool thing is with basically all the modern calibration software now, is that, you know, once you have that kind of master model of what the display outputs.

01:32:29:23 - 01:32:55:02
Joey
Yep, you can make a rec. 709 LUT, you can make a P3 LUT, you can do Rec 2020 or HDR if you measured Rec 2020. So if you measured HDR, right. That's the one place where this does fall on its face a little bit is you would have to measure the monitor in HDR. But the idea is you get this sample of data of what the monitor actually outputs, and then you match that up with what you want it to output.

01:32:55:02 - 01:32:57:20
Joey
And that can be different things depending on the need.

01:32:58:01 - 01:33:22:00
Robbie
Yeah. And just like, you know, you know, a lot of things in post-production, starting with a wide end of the funnel will get you to those those results better. So if you if you know that you're going to need to, have a display that can switch between, say, 2020 or P3 and 7 or 9, and you only want to do it once, well, then start at the wide end of the funnel and then you can derive down down from there.

01:33:22:02 - 01:33:48:11
Robbie
So there was one more thing I wanted to mention that has to do kind of kind of, pardon the pun, closed the loop on that closed looped, setup. And that is calibration software can also have direct device control, potentially on particular monitors. So we got the meter meter, reading the monitor itself. We have that in the pattern generator talking to calibration software to kind of collect all the data and do that, that difference modeling.

01:33:48:13 - 01:34:11:18
Robbie
But the calibration software can also talk to the display and say, oh, well, now I've created a lot. Let me automatically put the LUT in the place where it should go on the monitor. And now you can do a verification that that what is correct and you're getting an active result. And that last part is really important, is that your calibration is only as good as that last step, verifying that the calibration actually is correct and works.

01:34:11:20 - 01:34:28:19
Robbie
I've read so I've seen so many times you were like, oh, I bought Calman or Colorspace or whatever, and I did a calibration and then I did a verify and now I'm getting delta values. That's the difference between what you read and the standard delta e values that are off the charts. What am I doing wrong? That indication is I'm wrong.

01:34:28:19 - 01:35:04:09
Robbie
Something's wrong. You didn't verify, the monitor didn't verify correctly, and you have a problem somewhere. Maybe it's levels. Maybe it's, you know, using the wrong gamut or the wrong gamma or something like that. And that part of it, to be honest with you, does take a little bit of research to figure out. Okay, I'm using this software with this meter, with this display, and trying to get all of those things to talk nice to each other does take a little considered setup, but it's again, you know, our friends, like our friends at our sponsor of the show, FSI, they have some great calibration guides on their website for, okay, you're using this monitor.

01:35:04:09 - 01:35:23:22
Robbie
This is how you use it with color space. This is how you use it, with, with Calman. So take a look at those for whatever monitor that you're using as well. Two of the things I wanted to mention and, the first one, I've had a little bit of a change of heart with over the years, and that is, meter replacement.

01:35:24:00 - 01:35:39:18
Robbie
So where you place your meter is, is actually kind of an important thing and how you place it. I've seen people at trade shows, you know, they're shooting the direct view monitor and they're like off to the side at an angle, you know, ten feet in the air pointing down. Like probably not the accurate way of working in general.

01:35:39:18 - 01:36:08:02
Robbie
You want to place the meter on a direct view monitor pretty close to the monitor. Right? A lot of these meters are going to have, they're either designed for direct contact onto the screen, or they might have a soft rubber hood where you can just put that rubber hood right up to the monitor. Here's one thing I've discovered with meter placement with direct view monitors, especially as we get into HDR workflows where HDR is really cranking that monitor, the monitor is going to generate more heat, right?

01:36:08:04 - 01:36:29:12
Robbie
So I used to put my meters right up onto the glass of the of the meter, right of the display. Rather, I have found that especially with HDR monitoring, I tend to back off an inch or two now just because it doesn't let that heat build up as much at the front end of the meter. Right. Which gets me, some more accurate results.

01:36:29:14 - 01:36:31:00
Joey
Just make sure the lights are off in the room.

01:36:31:05 - 01:36:47:08
Robbie
And that's another thing too, is that you want to try to mimic the environment that the monitor is actually going to be used in. So don't do your just, you know, if you're in a black box, you know, kind of, color sweet. Don't do your calibration with all the lights on in the room. Do it kind of mimicking how that display is going to be set up in the real world.

01:36:47:10 - 01:37:13:05
Robbie
And then one more consideration. A special consideration for this is projectors. Projectors are a different beast altogether than direct displays. Certain most of that based on, say, certain, but most of the higher end color emitters and spectrums are going to also be available with spotting optics, where they'll actually have a viewfinder of some sort that you can use, to look at and line up the display.

01:37:13:05 - 01:37:31:14
Robbie
Because on a projector, you're not walking right up to the screen and measuring it from a foot away. Right. You might be 10 or 15ft away and you need to measure that and get that lined up. So if you are doing a lot of projectors as well, look at meters that have spotting optics in them, they're going to add to the price of the, of the meter.

01:37:31:14 - 01:37:35:06
Robbie
But they're definitely worth it to have that situation.

01:37:35:08 - 01:37:58:22
Joey
Now I want to talk about one thing that I don't think gets mentioned enough when you talk about calibration, and that is what calibration can't do, because there's a lot of times you run into a situation where somebody says, okay, my monitor's calibrated, I know I'm right, but they're wrong because the calibration can't fix everything. It is not a solve all.

01:37:59:00 - 01:38:23:16
Joey
If when a monitor cannot display a color that the standard asks for, you can never calibrate that away, right? Biggest example of this OLEDs as that white pixel turns on in HDR, the color volume starts to collapse and there are colors that they cannot display. They just will not do it. They cannot output that wavelength of light at that intensity.

01:38:23:18 - 01:38:43:05
Joey
There is no amount of calibration that will ever make that go away. And it's important to just be cognizant of that because you don't want to kind of have the expectation that, yes, good calibration is very, very important, but it will not be a solve all for every display issue.

01:38:43:07 - 01:39:04:12
Robbie
And even simpler, observation like that is, you know, there are there are not many display technologies that can hit 100% of, say, Rec 2020. Right. Like laser projector comes to mind, something that can do it. But you might have a display that can do, I don't know, just pick your number out of a hat. You might have a display that can do 90% of rec 2020, right?

01:39:04:14 - 01:39:15:19
Robbie
You can't invent extra gamut from your display, right? If the display is only capable of doing red, green, and blue out to this amount, you're not going to get extra by calibrating, right?

01:39:15:19 - 01:39:26:04
Joey
So generally speaking, an important thing is to remember is that calibration is essentially subtractive, right? You start with the wide native gamut of display. And now we're shaping that into the standard.

01:39:26:08 - 01:39:56:01
Robbie
Yeah. And that's why I actually I'm glad that you brought this up because that it's another reason we were talking about color bars at the start of this conversation. But it's a vital reason to understand that prior to calibration, there's there's certain things that you really want to make sure that you do, warm up time being probably the the most key one turning on to display, putting actual signal up on the display and letting it just sit and warm up for, you know, ten, 15, 20 minutes.

01:39:56:03 - 01:40:19:20
Robbie
You're going to get much as displays warm up. They produce different results. Right? So getting that kind of, display sort of, baseline, if you will, for its warm up time. Same thing goes. And this is going to sound like a funny one. Same thing actually goes with temperature. In a room like, if your temperature varies greatly in a room, you can actually get really significant different results from time to time.

01:40:20:00 - 01:40:44:08
Robbie
So what I tend to do when I walk into a room, turn the display on, put some signal up, and as I'm unpacking, you know my gear, let the display warm up. But also equally important, even if you have really good colorimeter and really good spectrum, plugging those in and letting those warm up and get acclimated to the ambient temperature as well for a number time is also a really good tip for getting better results.

01:40:44:09 - 01:41:01:09
Joey
Yeah, you don't want you don't need to say, okay, you have to calibrate in this temperature. But however, let's say you had your spectral and your colorimeter sitting in the trunk of your car and it's 30 degrees outside. Yeah. You bring them into a 70 degree room and immediately start taking readings. That's going to be a problem. Yeah.

01:41:01:10 - 01:41:09:17
Robbie
And same thing goes with humidity and all that kind of stuff. Right. We just want some time to acclimate, acclimate to whatever the environment is that, we're actually doing the reading. And with that.

01:41:09:17 - 01:41:14:15
Joey
All we're doing there is the same thing that we're doing kind of across the board in this whole process. We're eliminating variables.

01:41:14:20 - 01:41:37:17
Robbie
Yeah, that's exactly true. A couple more things here. I think that, as we've gotten in as the years have gone by and these tools have become more democratized and more people are thinking about calibration and more people are doing calibration, you know, I think a lot of people realize that it is that difficult, but it is a process.

01:41:37:17 - 01:42:00:22
Robbie
Right? And we have seen, I think, in the past five, six, seven years, especially people like Sony, Flanders and others, and starting to integrate what they refer to as, you know, sort of a general term of this is auto cal technology, right? Where the idea is that, hey, you know what? Computers, all this other stuff, like, we can just kind of do it for you.

01:42:01:00 - 01:42:19:19
Robbie
And so the way that auto cal capable displays will work is that essentially you just plug your meter directly into the monitor, that's the closed loop, position the monitor and let it do its thing. For example, I think ISO is the company that has a lot of good monitors with a built in, monitor that kind of pops out and comes down, measure the top of the display.

01:42:20:00 - 01:42:45:04
Robbie
Same idea, right? Is that there is auto calibration that can come up. And in my experience, auto calibration, used to not be very good and is now pretty rock solid. And I'll be the first one to admit destroy it. And, to my friends, that portrait, my friends at Color Space, I have to say, with the recent crop of Flanders monitors, which I use, the auto cow, it's acceptable.

01:42:45:04 - 01:43:01:16
Robbie
Good. It's acceptable. So it gets. It gets me to the place where it's like, okay, well, I don't have to break out the laptop. I don't have to break out the pattern generator. I have to worry about all these cables running. Never just plug a meter into the monitor and go. Now, with that said, it's not perfect for every situation.

01:43:01:16 - 01:43:19:17
Robbie
There might be places where I'm like, why don't I'm not really trying to do a calibration. I want to do things like a volumetric analysis of this monitor, or I want to do like I need to test like light output at different stimuli, like whatever. In those cases. Yeah, I might I'm not going to be doing auto cal, but auto cal is an option for some monitors out there.

01:43:19:19 - 01:43:25:23
Robbie
And you know, your mileage may vary, but it's gotten a lot, lot better with that kind of thing over the past couple years.

01:43:26:01 - 01:43:27:17
Joey
Yeah.

01:43:27:19 - 01:43:46:03
Robbie
All right. And the last thing here, Joey, is there's always help. There are professional collaborators out there who exists in the world, and this is all they do. Now, if you're wondering yourself why I'm able to find a calibrator, look in the home theater markets, if you. I know this is hard to believe, but the home theater market's a lot bigger than the post-production market.

01:43:46:05 - 01:44:18:17
Robbie
So a lot of people who are professional collaborators, where they're making their money is going to people's houses to do their TVs or projectors, etc. but oftentimes those people have the tool sets, to come and do, displays, like that. We use in post-production as well. The one little thing that you'll find that sometimes a hassle with the professional calibrator is that used to be doing home theater stuff they might not be as up on, like lookup table workflows as they are on just adjusting the the controls on the display itself.

01:44:18:18 - 01:44:41:08
Robbie
So, you know, when you if you are seeking out a calibrator, just ask them the comfort level with creating lookup tables. Because for us, in post-production, that's likely going to be the way that the calibration is stored is in that isn't that lookup table. And then also there are plenty of places out there, you know, where you can get training on, Calman, you can get training on color space, their respective websites just being two of them.

01:44:41:10 - 01:44:58:09
Robbie
But also keep in mind that there are places that will rent meters and rent some of this gear too. So if you own a good. Colorimeter. But you don't want to spend ten grand on a on a spectrum, but chances are you could rent a spectral for a couple of days, use it for, you know, building your offset matrix and then go from there.

01:44:58:11 - 01:45:00:00
Robbie
So that's always an option as well.

01:45:00:04 - 01:45:24:13
Joey
So I hope this has helped you kind of get at least some understanding of what calibration is, why we need it, and kind of how you can approach the calibration problem for your own workflow. As always, thanks so much for listening. You can find us on YouTube, Spotify, OffsetPodcast.com, and anywhere else you listen to podcasts.

01:45:24:13 - 01:45:34:10
Joey
And, you know, if we missed anything, you want us to dive any deeper into any of these concepts, please just leave us a comment and let us know. So, for The Offset Podcast, I'm Joey D’Anna.

01:45:34:12 - 01:45:36:05
Robbie
And I'm Robbie Carman. Thanks for watching.