To aid in setting up a colour analyser, the frameline of the LAD Control Film is opaque so that it will produce a "reference white" on the display. This "reference white" will be a much whiter white than any white of highlight in the scene and is not affected by the setting of the analyser controls.
The LAD patch and the six-step grey scale are along the bottom edge of the frame. A neutral density filter is placed at the lower left-hand corner of the analyser's display. (i.e. on the face of the picture tube). The LAD Control Film is positioned in the analyser gate so that the "reference white" frameline is displayed through the neutral density filer, providing a "reference grey". The calibration controls of the analyser are then adjusted to produce a visual match of the LAD patch with the "reference grey". A silver neutral density filter of 0.70 is a good starting point to produce an analyser display corresponding to a 1.0 neutral density. In addition, filters may be chosen to provide a reference for gamma adjustment.