A Crash Course On Color Bars

SMPTE color bars

SMPTE color bars

Color bars are a necessary reference tool for anyone in video production. They help technical directors, camera operators, and editors calibrate their equipment to ensure accurate color representation and consistency across cameras and monitors. Knowing how to use them is important. A few years ago, I found a great tutorial at Video University on how to adjust your video monitor using color bars. Be sure to bookmark the article for future reference.

  1. Allow the monitor to warm up for a few minutes
  2. Dim the room lights and block any reflections on the monitor
  3. Feed color bars to the monitor either from a camera or “house bars”from your editing system
  4. Set the contrast also called “picture” to its midpoint
  5. Turn the chroma also called “color” all the way down until the color bars
    are shades of black and white

Next, you will need to adjust the brightness and the contrast of the image by using the three narrow bars at the bottom right.

barswhi3

Brightness

Notice the three narrow bars labeled 3.5, 7.5 and 11.5 on the bottom right. Adjust the brightness control until the middle (7.5 units) pluge bar is not quite visible. The lightest bar on the right (11.5 units) should be barely visible. If it’s not visible, turn the brightness up until it becomes visible.

Since 7.5 units is as dark as video gets, you should not see any difference between the left bar (3.5 units) and the middle bar (7.5 units). There should be no dividing line between these two bars. The only division you should see is between 11.5 and 7.5

Contrast

The next step is to set the contrast control for a proper white level. To do so, turn the contrast all the way up. The white (100 unit) bar will bloom and flare. Now turn the contrast down until this white bar just begins to respond.

Color

Adjust the hue of the monitor until the Yellow bar is a lemon yellow, with no shades of orange or green. Adjust the Magenta bar until you eliminate the red and the purple. If you aren’t confident in your ability to “eye-ball” these shades, consider the following:

Many professional monitors have a blue-only switch. If your monitor has one, switch it on. If your monitor does not have a blue-only switch, you can use a piece of blue lighting gel. Hold it to your eye like a viewing lens. If you see any of the red, green or yellow colors, double the blue gel over to increase the blue effect.

By using the blue-only switch or a piece of blue gel, you have removed the red and green elements of the picture. Only the blue remains. If the tint and color (also called “hue”) are correct, you should see alternating bars of equal intensity.

bluediag

  1. With the blue switch on (or your blue gel in front of your eye) turn the chroma or color until the grey bar at the far left and the blue bar at the far right are of equal brightness. One trick is to match either the gray or blue bar with its sub-bar.
  2. Adjust the hue control until the cyan and magenta bars are also of equal brightness.
  3. You can also match either of them with their sub-bars. Now the four bars – gray, blue, cyan, and magenta should be of equal intensity. The yellow, green and red (which are black in the diagram) should be completely black.

You should now have a properly adjusted video monitor. However, if flesh tones don’t look right, you may need to make further adjustments to the chroma and hue.

Bookmark and Share

Leave a Reply