How to Set a Video Monitor or TV to Color Bars
If you are watching television and the hue or saturation is off, you can adjust it simply with your remote. What do you do however, if you're shooting with a camera and the color is wrong? How do you know if it is the camera or the monitor? If you're using multiple cameras that don't match how can you tell which one is right? The answer is using a video signal generated by each of the cameras or by a signal generator to set up your monitor ahead of time. Video professionals use a signal called color bars. You'll actually find it as a color reference on some DVD's today. Here's how to use that signal to set up your monitor.
- Difficulty:
- Moderate
Instructions
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Begin by allowing your monitor to warm up for several minutes. Be sure to dust it off, cleaning it if necessary. Dim the room lights. If you are shooting outside, keep the monitor in the shade or use a hood and make sure that there are no extraneous reflections on your monitor. Send a color bar signal to your monitor from your source. The bars illustrated are from the Society of Motion Picture and Television Engineers and are known as SMPTE color bars. There is no guarantee that the colors you are seeing here are what should be displayed if your computer monitor isn't properly adjusted. The long bars should be from left to right gray, yellow, cyan, green, magenta, red, and blue. Remember where the red bar is.
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Start your monitor adjustments by setting the contrast to mid and turning the color, or chroma, all the way down. Some monitors have a color off switch. Set the contrast to the mid position. Note the three small gray bars below the red bar. You should see three different brightness levels. They are distinguished by differing IRE levels a measurement of voltage established by the International Radio Engineers. From left to right they are at 3.5 IRE, 7.5 IRE, and 11.5 IRE. Adjust the brightness control until the middle bar at 7.5 IRE is just below being visible. In NTSC (National Television Standards Committee) video, 7.5 IRE is as dark as it gets. It should match the bar to the right at 3.5 IRE with no line between them. The next bar to the right at 11.5 IRE should be barely visible, so adjust the brightness accordingly.
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To set the contrast, turn it all the way up. Note when the white bar at the bottom at 100 IRE starts to bloom. Back it off until the point where it starts to happen. If you shoot on a professional NTSC video camera with a black and white monitor, this is the same technique that you'd use to adjust it prior to shooting.
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Now it's time for the color. Turn the color back up or on. Adjust the hue so that your yellow bar is lemon yellow and your magenta is neither purple nor red. Adjust the chroma or saturation so that the colors don't bloom and you're done.
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On professional monitors where color adjustment is critical, you'll find a blue only switch. With an amateur television or monitor you can get the same effect by looking through a piece of booster blue gel. Adjust both the chroma and hue controls until there is no difference between the long bars on top and the short row of bars immediately below them. The bars in blue should look as displayed.
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As a final check, look at some video that you've seen before as a reference. If your hue or saturation is off, especially on faces, tweak your controls. Then go back and look again at the full color bar signal. Remember how the bars look now. This final step is part of the process of training your eye as to how your color bars should look.
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