Calibrating Monitors

[Ken Tanaka]

"Those other bars" could be anything. The value of SMPTE bars is that each area consists of specific chrominance and luminance values. So if there're no reference values you cannot have true calibration, by definition.

[Josh Bass]

True, but aren't there "legit" bars that have that pattern? I see them at the beginning of agency tapes sometimes. . .doesn't seem like a production company would be using fake bars.

[Robin Davies-Rollinson]

I think you must be talking about EBU (European Broadcasting Union) bars. Thery are our standard bars and we line them up to a vectorscope where we can see the chroma level and also if the chroma phasing has to be rotated to correct or not.
Just as standard here as are yours accross the Pond ;-)

Robin.

[Josh Bass]

Makes sense. However, I'm not usually (or, heck, ever) able to use a waveform monitor and vector scope. I was just wondering if there was some method by which people calibrate their monitors to these bars.

[Jeff Donald]

You can only calibrate a monitor to a known accurate source for the bars. Calibrating a monitor to bars off a tape is of almost no use. You would need a scope and proc. amp etc to verify the bars and correct them if needed.

[Josh Bass]

Sorry, let me clarify. I didn't mean to imply that I was trying to calibrate to taped bars. Some lower-end cameras generate this style of bars. I figure, though it may not be perfectly accurate, wouldn't calibrating the monitor at least give you SOME idea of what you're actually getting? I used a lower end Sony cam a few weeks ago (TRV950, I think. . .little tiny thing) and it had that style of bars.

[Jeff Donald]

It is almost impossible to adjust for the NTSC requirement of set-up with the pluge in the color bars. PAL doesn't have set-up so no pluge in their bars. Phase can be set by using a blue filter and adjusting the bars to match grey levels. Not easy to explain, sorry. But it is all a waste of time if the bars are off.

[Josh Bass]

Okay, well, then I guess that's the way it is. Thanks anyway, guys.

[Sean McHenry]

Well, don't let all this discourage you too much. There are ways to calibrate most monitors, and even Televisions with color adjustments for RG and B if they are on separate controls.

You will need a way to get an accurate color bar image to the screen. If you use a laptop or PC and call up some of the preset color bar images, or use a Calibar or Calibug, you can convert your VGA output to composite or S-Video with the correct devices (scan converters). Or, if your monitor has RGB inputs, they make a special "breakout" cable that connects to your 15-pin VGA and has 3-5 BNC connectors or RCA connectors. Plug that into your input.

There are directions on more professional sites about how to actually do the corrections.

There is even a way to simulate a "Blue Only" function by using a deep blue gel in front of the screen. You'll read about Blue Only on the other sites.

I know it's not 100% accurate, especially if you use converters but it's better than nothing.

Good Luck,

Sean McHenry

[Josh Bass]

Thanks. Keep in mind, the problem was with the bar source, not the monitor. I'd need a bar source in the field.

[Sean McHenry]

Ah. In that case, look into the Calibug. I have not used it but I believe it is basically a USB drive with various images on it with the test patterns you can use with a laptop or other PC like device that has an S-Video output.

Also look for the Newtek (Yep, the 3D software folks) Calibar. It was the size of a large pen and had a BNC on the end of it. Push the button(s) and get test patterns out of it. Great idea really. Small enough to carry everywhere but a bit pricey. I am not sure it is even around anymore. The Calibug is also made by the Newtek folks I believe.

Google for it. It's out there.

Sean

[Josh Bass]

Ok, those sound like good solutions. However, I don't have a laptop. Is there something that just plugs right into a monitor?

[Sean McHenry]

Yes, look at sites like Markertek and TecNec (really the same company) - Sorry Boyd. B&H likely has them too but I know the others do. Maybe get the products from those sites and see if B&H has them.

If you really get stuck to find something, let me know and I'll work with you through my place. Sponsored by B&H or not, if they don't have it, you should look elsewhere for what you need.

Do a search on the sites for Bars Generators or Color Bars, etc.

Sean

<<<-- Originally posted by Josh Bass : Ok, those sound like good solutions. However, I don't have a laptop. Is there something that just plugs right into a monitor? -->>>

[Josh Bass]

thanks.

[Dwight Flynn]

How do I go about determining if my jvc tm-h1375su ntsc/pal monitor is calibrated correctly?

Thanks