ProAVmag

How to Calibrate Videowalls

Ever been to a network operations center you didn't do the AV for? Had a burger in a sports bar with multiple flat-screens? In either case, have you stopped to notice the differences from screen to s 6/04/2008 4:59 AM Eastern

How to Calibrate Videowalls

Ever been to a network operations center you didn't do the AV for? Had a burger in a sports bar with multiple flat-screens? In either case, have you stopped to notice the differences from screen to screen? (Of course you have.)

Credit: Courtesy NEC Solutions

Ever been to a network operations center you didn't do the AV for? Had a burger in a sports bar with multiple flat-screens? In either case, have you stopped to notice the differences from screen to screen? (Of course you have.)

Not a huge deal perhaps, but when it comes to today's multi-panel videowalls—screens stitched together to create digital signs—not only should each screen look great, they should look the same. To produce a consistent image, each display needs to be accurately calibrated to the same performance standards. Here's how:

  • First, individually calibrate each display in the videowall as if it were being used as a single display. Calibrate the white balance (grayscale tracking), black level, peak white level, color, hue, and sharpness controls (if provided).
  • Because every display in the videowall will be calibrated to the same reference test patterns, the coloration and black level of all displays should match exactly. However, because the peak white light output level is normally adjusted on each display according to the individual circuit capabilities, the maximum light output of each display may be slightly different, as checked on a 100 IRE (Institute of Radio Engineers) test pattern.
  • After each video display is individually calibrated, match the maximum luminance output levels across all displays. To do this, use a light level meter to check the luminance output of each video display with a 100 IRE white window test pattern.
  • Note which display has the lowest luminance output. Then, while measuring the luminance output from the 100 IRE white window on each of the other displays; decrease the contrast control on each display to match the luminance level of the lowest output display.

Now all the displays in the videowall should match exactly, and a picture split across all the displays to form a larger picture should be uniform from one display to the next.

—Tom Schulte contributed to this story.



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