A bar that is slightly brighter than black (often +2% or +4%). Why Calibration Matters
Dim the lights. Calibration is most effective in the lighting conditions you’ll actually be using to watch movies. Give your eyes a few minutes to adjust to the darkness. 2. Locate the Bars pluge pattern
The human visual system exhibits non-linear sensitivity to luminance changes, governed largely by the Weber-Fechner law. In dark viewing environments, the eye is relatively sensitive to small changes in luminance near black, provided the eye is dark-adapted. A bar that is slightly brighter than black
The PLUGE pattern remains an indispensable tool in the repertoire of video engineers and calibrators. Its elegant simplicity—a visual representation of the threshold of visibility—allows for the objective alignment of subjective visual perception. While modern display technologies like Local Dimming LCDs and OLEDs introduce new variables regarding dynamic processing and absolute black levels, the fundamental logic of the PLUGE signal persists. Give your eyes a few minutes to adjust to the darkness
In HDR, a specific PLUGE pattern is used not to set a user control, but to verify the Electro-Optical Transfer Function (EOTF) tracking. The pattern typically includes bars at 0.005 nits, 0.01 nits, and 0.02 nits. Because the PQ curve specifies absolute luminance, the calibrator checks if the display can resolve the specified low-light values without clipping.
| What you see | What it means | What to do | |--------------|----------------|--------------| | Left bar visible | Brightness too high | Lower brightness | | Middle bar invisible | Brightness too low | Raise brightness | | Right bar invisible | Brightness much too low | Raise brightness significantly | | All bars equally gray | Brightness extremely high | Lower brightness aggressively | | Left invisible, middle just visible, right clearly visible | Black level correct | Stop |