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The Background Image zone consumes a video decoder on the BrightSign player. If the player model supports two video zones (e.g. XTx43, XDx33), it can support one video Background Image zone and one Background Image zonevideo zone (or more with Mosaic mode), while single-video models (e.g. HDx23, LS423) do not support both a video zone and Background Image zone simultaneously. Note that on some models this rule does not apply to Mosaic mode presentations.
If you only want a background color (instead of an image), do not add a Background Image zone. Instead, change the background screen color in theFile > Presentation Properties > Maintab.