Datavideo DVK-400 Instruction Manual page 40

and adjust the mask until the unwanted elements are completely removed. The yellow rectangle
specifies the mask edges and is drawn for illustration purpose.
In the red rectangle at the bottom left corner of the diagram below, because of uneven distribution of
light, the mask edge is vaguely seen.
To remove mask edges entirely from the composite view, increase the "Border" value to soften the
edges. As shown in the diagram below, mask edges disappear and the image areas around them are
smoothened.
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