The Importance of Monitor Calibration

Bob Zelin Orlando Florida USA CreativeCOW.net. All rights reserved.

In this article from The Creative COW Magazine, Bob Zelin discusses the imporance of monitor calibration, different monitor options and how to execute the calibration on these monitors.

If I told you that monitor calibration was not only important but critically so, I am sure that some at the Creative COW forums would argue that point. The question some might ask, is why bother? Good question. And there's really only one reason to bother with scopes: If you want anyone else to see your pictures.

Wait a minute, you say: "My HD pictures look fantastic! I've tweaked the monitor in my room to within an inch of its life and the color is stunning!"

And that's the problem. I don't care one bit if the picture is "stunning." We need to observe accurate color, color that will not get rejected, color that will be consistent at other professional facilities, over the air, or at your client's place.

That's why a consumer plasma TV whose chroma is cranked way up, and whose colors are jumping off the screen - "Wow, look at the colors! I can get a suntan from that screen!" - is worse than useless. It doesn't project an accurate image, no matter how nice the picture looks. A set-up like this will eventually get you into trouble.

We do this for a living, so we need to see what others see and I'm not talking about your mom's 42" DLP.

The most important thing that accurate monitors can do for us is to show us noise and other defects in the pictures. We can't afford to mask problems.

The whole point of all this techno mumble jumble is standards: ensuring a consistent viewing experience for everyone who sees your images, regardless of the setting. You can accomplish this by setting up a proper viewing experience in your studio.


MONITOR SET-UP

The absolute cheapest "very good" quality HD-only monitor is the Dell 2407WFP, that sells for around $700. You use the analog HD YPbPr signal from your video card to feed the RCA inputs of this monitor. It works just fine.

There are other great monitors out there and more coming all the time. But for now, you won't get 1920 x1200 resolution HD monitoring any cheaper than this.

In the Gear Round-up in the May-June '07 issue of the COW Magazine, I talked about the new VidScope HD software from the UK company, Hamlet. The software is PC-only, but even die-hard Mac users shouldn't hesitate to jump in. The total of the software, a video card from AJA or Blackmagic to feed the video signals, and the computer to run it in, combined costs a small fraction of less-flexible standalone HD scopes. The least expensive HD monitoring ever? More features than anything else? Throw in a free 30-day trial for the software, and this one is a no-brainer.


CALIBRATION

These are the general principles that will apply whether you're using Hamlet or an outboard monitor. They also work equally well for SD monitor calibration.

Start with the SMPTE Color Bars.

Switch to the "Blue Only" mode, which will make your image look black and white. Adjust your hue or phase adjustment so that all areas match in intensity.

Here's a close-up of the lower left area of your color bars in "Blue Only"


Adjust your chroma level so that the colors in the thin stripe that separates the top color bars from the bottom match in intensity. You want them to look the same.

Get out of blue only, and look at the bars in color. If you turn up the brightness, you will see in the blacks on the lower right, two different levels of black. This is called "pluge." It rhymes with Scrooge, and it stands for, what else? - picture line-up generation equipment.

Adjust your brightness by eye, so you can just barely see the "brighter" black signal, but not enough so that it disappears. Since we're in print, we've goosed the "brighter" black, which you'll find in the lower right section of your bars.

This is called "blacker than black," which you don't want. Otherwise, you lose detail in the black parts of the image, also known as "crushing" the blacks.

The Contrast, or white levels, adjustment is purely subjective. The old rule of thumb was to increase the contrast while looking at the 100% white bar, until an old CRT would "smear." Except that modern CRTs, and of course LCDs, don't smear. So turn it to whatever looks correct to you. This will be the brightest your monitor will get.

Forget the specific "black and white" adjustments you see on many scopes. These were for setting RGB Gain and Bias for an old CRT monitor, to make a black and white image look black and white, without any pink or blue hue. There's no Gain or Bias controls in LCD, plasma and DLP monitors.


THE REAL WORLD CHALLENGE

As you can see, calibration isn't super-difficult. It has a few steps, but they're each easy enough to take. If you do, you wind up with an accurate picture that will hold up through the whole production process all the way out to broadcast or your client's office.

Of course there are complications. There are always complications. One of the most common is when you're dealing with BetaSP and Digibeta machines. These are still a huge part of the broadcast scene, and an even bigger part of the film festival scene. You may also wind up using BetaSP and Digibeta archive tapes in your mixedformat projects in Avid, Final Cut or Premiere Pro.

So whether you shoot primarily in SD or HD, you're going to run into the problems. The good news is that you can overcome them.

Not that you're going to get any help from the SMPTE committee in the US. When setting up the SMPTE 259 and associated standards for serial digital video (SDI), they made some assumptions about the relationship between analog and SDI signals, and how they'd be used together. The basic assumption was that they'd never be used together. But of course they are! Every day! And the SMPTE standard can cause problems when you do.

Here's a simple example. The color black as definined by the National Television Standards Committee (NTSC) has a setup level at 7.5 IRE if you look at an analog waveform monitor. IRE is a unit of measurement for video signals defined by - you guessed it - the Institute of Radio Engineers. Don't ask.

Now, imagine that you take a tape that shows 7.5 IRE on your analog BetaSP deck. The same tape will play back with a black level at zero IRE in a DigiBeta deck. You can see this especially clearly if you have a TV monitor that can show SDI and analog (like a Sony PVM-20L5/1) and a Waveform Monitor that can show SDI and analog (like a Leader LV5100D).

The same tape showing 7.5 on one deck and zero on another? What's a normal person supposed to do with something as ridiculous as this? The good news is, nothing. Don't do a thing.

Because if you set the black on your BetaSP deck to 7.5 IRE, that tape played through SDI on a DigiBeta deck will be dark at both your place and at the broadcast station and film festival where your tape plays.

Again, audio is a whole article in itself, but note that the same thing is going on. You know that your BetaSP levels should come in at zero dBFS ("decibels full scale").

Take the same tape to a DigiBeta machine, and those levels will shows up as minus twenty on a Digibeta machine. But if you set the analog BetaSP levels to -20, they'll get pushed down even further by the digital VTR.

The solution once again: set your analog levels properly, and leave them alone for playout through a DigiBeta machine.

Aren't standards fun? At least it's easy to do nothing.


ONE MORE CHALLENGE

While we're talking about monitoring the same tape in different formats, here's a word about trying to monitor HD and SD on the same monitor: don't.

I just installed a Panasonic BT-LH2600W LCD to replace to replace the Sony PVM CRT for an Avid customer who does primarily SD (not HD). Four hours later, they called me to get it out of their edit room because the SD was simply unacceptable.

I've already told you my favorite choice for a cheap HD monitor. But the SD on that one is unwatchable too. The best bet for SD monitoring is to head down to Walmart and buy a cheap old CRT TV.

Even though most of us will need high-quality SD monitoring for the foreseeable future, it ain't gonna happen on LCD. No one's even trying to develop a fantastic new SD LCD monitor. You're best off using separate monitors for HD and SD.

Now if you have the bucks, there is one • and only one • choice that actually does a good job with both HD and SD monitoring, the Panasonic BT-LH series.


The Panasonic BTLH900 does a very good job displaying accurate color for both HD and SD Images

The 900A has a street price just under $4000...for a screen with an 8.5 inch 4:3 diagonal? Eight and a half inches! That's something like $470 per inch. But in fairness, this monitor really does do every broadcast format from 1080/60i to 480 i/p - even automatically switching the monitor setting to match your input signal.

Now, if you really have the bucks, you should get two 30" LCD monitors. This will give you a 5-foot span between the two ends of your monitors. You'll get a chance to exercise your neck muscles while you're eating cheeseburgers and French fries all day long. And with that 60" span across both monitors, your arm will get a workout, dragging that mouse back and forth all day long, instead of barely moving it on a 20" display. And if you use reading glasses, believe me, with two 30" monitors, your fonts will look real big. Who needs glasses?

See? Nobody looks after your health like your old pal, Bob. And hey, if you still need help with calibrating your monitor, drop by the COW's Broadcast Video forum - there's help there.

Bob Zelin
Orlando, Florida

Bob Zelin is an old cranky video engineer that got his start in the professional audio business in 1977. By 1981, he was fired so many times, that no one wanted to hire him, so he started his own company in 1982. Today, Bob resides in Orlando, Florida, terrorizing southern editing facilities. He is nevertheless one of the industry's most respected systems contractors. You won't have to look hard to find him at The COW: he posts around 10 times per day across over a dozen forums.

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