What’s so special about these color bars?

You’ve seen these before. In fact you’ve probably seen them a thousand times before, or some variant of them. They’re referred to specifically as “SMPTE Color Bars” and they were developed by the Society of Motion Picture and Television Engineers to calibrate color TVs. They don’t have much use in today’s flat-panel, HD world but back when everything was analog, they were super-duper important. Now they’re just a geeky icon.

How they worked back in the day

Here’s what a TV repair person would do, back in the day. They would have three different pieces of colored glass or plastic that they would look through. Each color would block two of the colored phosphors of the TV, so they could see just the red, green, or blue parts of the image. If the TV’s tint was set right, the images would look like this:


Just Red


Just Green


Just Blue

If the TV repair person saw anything other than these patterns, they could adjust the tint or individual colors. This was a quick, basic way to make sure that a color TV was doing what it was supposed to be doing.

Remember…

Televisions, especially those before the mid-1970s, were finicky beasts. They needed frequent adjustments, and the color was nowhere near as good as today’s TVs, even when they were properly calibrated.  Back in those days, TV repair was a pretty profitable business, and TVs needed repairing a lot.

The bars did other tricks, too. Using the grey/black bars at the bottom would allow brightness and contrast to be set, and looking at the edges of the bars would show issues in alignment and focus. In short, this was one useful image.

Starting in the mid-1970s, TVs included very simple computer circuitry which stopped a lot of the drift in color, brightness and contrast that happened naturally. Every year after that, TVs got more reliable and cheaper. By the 1990s it was pretty hard to find a TV repair shop that wasn’t struggling. Instead, former TV repair people became “integrators,” offering calibrations for high-end video systems.

Past meets present

Today, with digital controls, those old-school color bars don’t do as much as ones like this:

Color calibration isn’t as difficult as it used to be and at the same time with LCDs we don’t worry about focus and alignment. So it comes more down to fidelity and consistency, something like this image is much better off testing. With an image like this it’s easy to check resolution, contrast, and overall fidelity. Using higher-end tools like this will help even regular users to make their TVs look perfect.

Since most people’s smart TVs can use images from a flash drive so loading them on your TV is easier than ever. In the past, it took calibration tapes or discs. Satellite TV users had to wait until a channel like HDNet (now known as AXS TV) ran color calibration images in the middle of the night.

Sure that new image is awesome…

…but somehow, it just doesn’t look as cool as an old-school SMPTE color bar, does it?

About the Author

Stuart Sweet
Stuart Sweet is the editor-in-chief of The Solid Signal Blog and a "master plumber" at Signal Group, LLC. He is the author of over 8,000 articles and longform tutorials including many posted here. Reach him by clicking on "Contact the Editor" at the bottom of this page.