Importance of Color Bars
Brian Peterson: Hi, I’m Brian Peterson.
Mark Montgomery: I’m Mark Montgomery.
Brian Peterson: And this is Tips and Techniques.
Mark Montgomery: Yes.
Brian Peterson: And we’re going to just do a tip and a technique, okay? Ready?
Mark Montgomery: Yes.
Brian Peterson: We normally try to do two, but this is one that actually, if we go along, can we make it two parts?
Mark Montgomery: Yeah, if we go along, we probably will make it in two parts, two segments.
Brian Peterson: So, actually, you were commenting a moment ago, we were having some technical difficulty with this thing back up. Yes, we have technical difficulties, too! And you were commenting something about, when you have technical difficulties, you see the bars and tones, we were having it because of we were trying to get bars and tones.
Mark Montgomery: Yeah. It’s a little irony here.
Brian Peterson: A little irony. Okay, let’s tell you what we’re going to do and then let’s do it. So, a lot of folks have asked us what, what is the importance of bars? And we’ll just talk about bars, and tones, and audio things, we don’t care about that, at least not now. So, what were your experiences with the needs for bars?
Mark Montgomery: Well, there’s, obviously if you’re shooting outfield, a lot of times you will want to include some way to monitor what you’re shooting. More than what you can see on your LCD screen. And so, having a production monitor is key, but you have to set it up, make sure that it’s seen what it needs to be seen appropriately. Calibrate it in other words.
Brian Peterson: Okay. And we’re going to show you how to do that in a fairly simple way. But there are certainly other parts in chain, but having a calibrated monitor is critical. So outfield it goes to the first place. So, there’s a couple of way you want to approach in the field. So, maybe you don’t have money for a field monitor, and they can be kind of expensive.
Mark Montgomery: Yeah.
Brian Peterson: Often times they’re battery powered, so, that adds a bit of expense, and weight, if you’re worked with one. But you may be using just your camcorder, and some camcorders have the ability to adjust the viewfinder level. So, it’s usually just a brightness and contrast control. And what we’re showing you here today, you’re going to actually used in at least some degree, in most cases, even if they’re most black and white. To at least get your Chroma settings correct, and your phase, and other hue settings done right, so that when you’re color balancing and you’re looking through your viewfinder, you can work your exposure correctly, so that’s the kind of the critical part about that.
Mark Montgomery: Right. It can also be applied to a television set, too.
Brian Peterson: Right, so you’re back.
Mark Montgomery: We’re schools are left accurate, in a real production monitor.
Brian Peterson: Right.
Mark Montgomery: It’s better than nothing.
Brian Peterson: So, we’ll show you how to do it with a production monitor, regular television, we’ve got a little plasma back here, which we’re not going to be using for this example, because we really wanted to show you the most common way this is done, and this is the setup here.
So, let’s pretend we’ve just acquired some footage, and we’re getting ready to do some editing. And we want to make sure that our editing environment is spot on.
Now, for a lot of you, sometimes all you’re using is this right here, and I’ll spin this around just for our main camera. You’ve got an editing environment, and you’re using this to do a lot of your color. If you can, don’t! Try to use a TV, a reasonably new TV, or a monitor.
Really, why don’t we talk about that for a second? The difference between the TV and a monitor really is very little, except two very important things. First of which, a monitor normally has more robust fosters, a traditional catoid ray tube, or CRT. The fosters hold their color better, you can leave the same image up for hours and you won’t get what’s called burn in into the fosters to the same degree as you would with a television that you just got from one of the local stores. The other thing about the monitor of course, you can’t watch TV. No tuner in it.
Mark Montgomery: Right. And a lot of times monitors, too, you know, use a color space. RGB versus YUV. Or commonly Y, CbCr, CrC…
Brian Peterson: Yes, the old alphabet of Ys, Y for outburst. The other thing in mini monitors that you’ll get, and this is something that we’ll show you how to do in two different ways, actually, is that it has the ability to turn off two of the guns, the red and the green gun. There’s three guns in a normal color CRT. And what you get as a result is just being blue, and we can see this in our other camera. And we’ll talk about why we do that in a moment.
So those are the three main differences of a production monitor or the regular TV. But considering you just have a regular TV, we’re going to approach it from that angle.
Mark Montgomery: Right. And just having those tools available makes it setting up so much faster.
Brian Peterson: Oh, yeah.
Mark Montgomery: But you can absolutely do it on television as well.
Brian Peterson: You certainly can. Older televisions tend to have a lot of problems associated with them, and so put it this way, if you’re looking for a rationalization to get a new TV, this might be one of those that you wouldn’t be able to really get accurate color, brightness contrast relationships. Older TVs tend to be a little bit darker as they age, and it’s just impossible, it becomes impossible to set them up correctly.
So, let’s just describe what we’ve got going on right here. So, we want to preview, and see what’s happening with a TV or a monitor, so by doing that, we’ve got our camera, we have, this thing is generated by our NLE software here, so the signal is coming out of the computer, going into our camcorder which is doing the translation into an NTSC signal, so it’s making that conversion happen from DV to NTSC projectable signal, coming in, going out, into here.
So, that’s the chain – generating here, interpreting here, and being shown on our monitor. Right? So, that’s the standard production environment. We would recommend you set up at home, if you haven’t already done that.
All right? So, our friend the color bars. Now, these aren’t any, any ordinary color bars, are they?
Mark Montgomery: No, no, they’re SMPTE color bars. What does SMPTE stand for?
Brian Peterson: SMPTE – Society of Motion Picture Television Engineers?
Mark Montgomery: SMPTE? Yeah, I think you got that right.
Brian Peterson: One of those, oh, ok, we’ve got Charlie doing this. I got it right this time. Blued on apty, got it on SMPTE. The thing with SMPTE color bars is they have certain qualities, and we’ll get to those in just a moment, that you don’t get from any, just any old color bars. You can get color bars off line, and it can be wrong. In fact, in most cases they will be. So you need to have them generated either from your software package, and it will say SMPTE color bars, or, actually will they always say SMPTE or not? I’m not actually sure about that, so don’t quote us. But we’ll tell you the things to look for.
Or, they can be generated from your camcorder.
Mark Montgomery: Right.
Brian Peterson: Many camcorders will do that as well. I recommend doing it from your NLE, because that’s really where your material is being generated from.
So, the things to look for. We’ve got really four different sections. We’ve got bars which are these pieces right here. Then we have what you either call blocks or chips, and that’s these pieces down here. And then we have this section in here which is, there’s actually technical term, there’s I and Q, and white, then we have black, and then your favorite word right in here, PLUGE.
Mark Montgomery: PULGE, that stands for Picture Lineup Generating Equipment.
Brian Peterson: Yeah, yeah. Mark will talk to you about that in just a moment. So, those are the components of SMPTE bars, and these are the bars that we would recommend you working with. Anything else really is going to put you in to dire straits, so don’t even try.
The SMPTE bars are actually generated at not a 100% a chromanence value, they’re actually about 75%, which is legal for broadcast limits. Now, when we hear the term legal in many different cases, we’ll only use it once. There’s white level legal, and there’s black level legal. We’re talking about a 100, actually, can we push it to a 105%, white legal. Black is 7.5 IRE. And we won’t even go into the IRE.
Mark Montgomery: Right.
Brian Peterson: It is I-R-E, not IRE, like you mentioned.
So, let’s talk about the steps in doing this together. We’re going to set our white point, our black point, our color intensity, and then our color phaser hue. And those are the basic steps in putting this together. So, you want to do this in order. It is important to do them in order. I’ll handle the white point, you’re going to be doing black, and let’s start with a different one, just for a moment.
We’re going to, we’ve made a square out of 0% black, this is 0, 0, 0, if you’re setting this up in Photoshop, or you’re in Manual Editor. And then, white for our purposes is not 255, 255, 255, it’s 235, 235, 235. That gets you at the right luminance level.
Mark Montgomery: Right.
Brian Peterson: So, we got this square in a larger square. And what we’re going to adjust here is our contrast level. And what we want to do is get the white as white as it will go, without starting to obscure the squareness of the square, and I know you probably can’t see it here, but in some cases, when you start cranking this contrast up, you start seeing some blooming into the black, and some, actually, some changes of the shape along the vertical edges here. You start seeing the sort of bleed over from that. So I’m just going to go over from low to high real quick, and we’ll see that. See how it starts blooming and the black becomes kind of grey? That’s what, it’s right at the point as it starts turning a little bit grey is where we want to stop. So, I can see a little more than you can, but there’s what you’re looking for. So, I’m going to say, about right there is it.
Oh, one other thing. If you have the opportunity, try to turn your Chroma off. All your colors. So, usually you have a saturation control, turn that all the way down. Now, on this monitor, we have Chroma clear. So just by hitting that, I eliminated all the colors. So, another nice feature with some monitors.
So, I can see that’s just about right. The black still stays black, the white is as white as it can get, we’re good. All right? So, we’re set there. Let’s move on to PLUGE, and setting up black point.
Mark Montgomery: Just real quickly, if you’re doing the contrast, that’s probably going to be labeled in your TV picture menu as contrast. There’s no confusion there.
Brian Peterson: Right.
Mark Montgomery: With PLUGE, you’re going to be changing, we’re going to be changing luminance basically.
Brian Peterson: Yeah, and it’s kind of missnumber, because it’s brightness that we’re cutting, that we’re using for black level.
Mark Montgomery: Right, right. So, in your TV, it may be labeled brightness, or something else.
Brian Peterson: It could be picture, something on that account.
Mark Montgomery: Yeah. Okay, what we’re doing here is we’re going to set up black level so that this monitor displays the appropriate black level meaning that the blackest part is registered. So you don’t get anything too dark or too light…
Brian Peterson: Yeah, so we can see detail in your black.
Mark Montgomery: Right, exactly. So there’s three, three bars here at the very bottom.
Brian Peterson: Let me turn it way up so we can see it them here.
Mark Montgomery: Yeah, yeah.
Brian Peterson: Here we go, right here.
Mark Montgomery: So we got your blackest black, which is, I think it’s set at 3.5 IRE, and then we have the one we want to register, which is set at 7.5. And then we have one that’s actually three more IRE up which is 11.5, which we don’t really worry about, but we want to keep our eye on it just to make sure it doesn’t get lost.
So, what we’ll do, we’ll adjust our brightness so that the 7.5 IRE bar gets lost with the blackest black, which is 3.0 IRE. So we want to make that bar blend in.
Brian Peterson: So, I’m turning it down now, and I can’t see it, so you’re going to have to tell me, down or up.
Mark Montgomery: Let’s go down a little. There we go!
Brian Peterson: Okay.
Mark Montgomery: Right about there.
Brian Peterson: Let me turn it back up just to show folks again. So, we’re right up there, let’s come back down, just lose the distinction between those two bars, got there?
Mark Montgomery: A little bit more. There!
So what that does, basically, is since we have a value of 3.5 that is the blackest black which is not acceptable. We’re going basically take the 7.5 and move it down so that the display is equal. That way we know that 7.5 on this display, we can’t tell the difference. So we know that that 7.5 level is the very bottom of what’s acceptable.
Brian Peterson: All right. So just those two points right there. Setting white point, setting black point, are your two first steps in setting these bar up, and, it sounds like we’re running out of time. So, I think this will become a two-parter. It gets fun now. We’re going to talk about using a blue filter. And even how to do one yourself if you don’t have a monitor capable of doing this on your own.
So, let’s hold this over until the next week, and we’ll continue with the color bar conundrum. See you next time.