IRE

IRE is actually an acronym for the Institute of Radio Engineers, but it is used as a relative measure to explain video output signals. IRE is a relative measure since video signals can be amplified.

The maximum >Amplitude of the output from a video camera would normally be set at 100 IRE, giving you the full Range from black to white in video output signal. 100 IRE will display the best image, brightness and contrast, while a 50 IRE will only have 50% of the contrast. At 30 IRE, the video output has only 30% of its original Voltage and is considered the minimum required to see a meaningful image.