Home FAQs ISF Video Calibration Is Video Calibration Permanent?

 

[ A ] Calibration is not a permanent process, primarily due to natural deterioration that takes place in the lamps used in DLP-, LCD- and LCoS-based displays and in the phosphor coatings used in plasma and CRT HDTVs.

With lamp-based displays, the color of light emitted by a new lamp is relatively variable during the first 100 to 200 hours of operation, but once that "break in" period has passed, the spectral output will be consistent until about the midpoint of the lamp's expected service life. Around this midpoint, lower peak light output is likely to be noticeable, and at this point shifts in both grayscale and color accuracy are likely to occur.

As a result, it's recommended that a lamp-based display be re-calibrated at around the halfway point of the lamp's expected service life. This will ensure that contrast ratio is optimized in view of the lower overall brightness of the lamp and that any drift in grayscale or color accuracy is addressed. From this point forward, calibration would not be required again until the lamp is replaced and a new lamp has completed its "break in" period.

Lamp life ratings vary significantly among manufacturers and for different types of lamps. Manufacturer claims are a good starting point for monitoring changing lamp conditions, but your eyes should play a leading role in determining when light output is on the decline and you're in need of re-calibration. In front-projection installations, particularly those where the screen size approaches or exceeds the recommended maximum for a projector, the falloff in lamp light output will become more apparent more quickly, and lamp replacement may required prior to re-calibration.

With CRT and plasma HDTVs, the aging of the phosphor coating that creates the images for these displays is gradual but persistent, and as that decay occurs, light output will decline and shifts in color will occur.

Re-calibration of phosphor-based displays is recommended around every 2,000 hours of use. To put that into calendar terms, if you watch your plasma or CRT-based HDTV an average of 4 hours per day, you should consider re-calibration every 18 months; if average daily use is more than 4 hours per day, annual re-calibration would be beneficial.

As with pricing in general, rates will vary among calibrators for re-calibration work, so this is something you should ask about when you're first looking to hire a calibrator.

Contributions to this FAQ article were made by the following ISF Forum calibrators:
21st Century Calibrations, Clearly Resolved, Coast Calibration, Mastertech Repair

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