how much color correction would be required to produce acceptable results with that light

There has been similar enthusiasm for studio LEDs elsewhere, and they have been used in the U.S. for filming popular prime-time reality TV competitions such as "Dancing with the Stars," "America's Got Talent" and "American Idol."

But now the EBU suggests it may be premature to embrace LEDs fully in the studio, even if they are now ready for the home. Problems that have been identified include inconsistencies between factory batches, insufficient brightness and inability to spotlight subjects, especially from a great distance. A further issue is that color LED lights are prone to color shifts and inconsistencies that can be especially evident when lighting people's faces.

The EBU is not suggesting broadcasters should avoid LEDs, but urges them to recognize that many new LED lights fail to perform as well as had been expected or promised. The EBU has come up with its own recommendation to help broadcasters assess how well their television lighting performs. Called R 137, and accompanied by a software-based analysis tool, this is designed to quantify how well a set of test colors is reproduced when illuminated under a given light and viewed through a standardized camera and TV system. The software compares the differences in colors produced by the light source under test with those rendered under standard lighting conditions. It assigns a value from 0 to 100 to each light tested, and that value gives an indication of how much color correction would be required to produce acceptable results with that light.

In addition to the value assigned to the light, the software also provides additional information that can be used to advise colorists on how much correction is needed. In cases where the value assigned to a light is less than 50, the results may still be unacceptable, even given a lot of correction.