Grass Valley LGK-3901 - Manual (Page 37)

GUIDE TO INSTALLATION AND OPERATION
LGK-3901/DSK-3901 | 31
4.8.5.5 Masking
The LGK-3901/DSK-3901 allows a rectangular masking area to be defined for each of the five keyers. This mask
applies to any signals fed into the keyer; external fill/key signals, or the output from internal stores (LGK-3901 only).
For internal images (LGK-3901 only), the area range of the mask is determined by the width and height of the image
in pixels, and is limited by the selected video standard. To maintain correct YUV values the pixel count will increment
in units of 2.
For external fill/key signals the area range of the mask is limited by the selected video standard. Again the pixel count
will increment in units of 2.
One situation where masking external fill/key is useful is when output from an external graphics device needs to be
split between two keying layers in different regions of screen area.