The output resolution is subject to the setting of the host output resolution regardless of whether it is single image, 2 or 4 split screen.
For example, the output resolution will be up-scaled to 1080p when TX input is 720p, host output resolution setting is 1080p.
The output resolution will be down-scaled to 720p in each two split screen when TX input is 1080p, host output resolution setting is 1080p.