©2018 NEC Display Solutions, Ltd. Page 33 of 71• EXPAND - Use EXPAND if the Compute Module is configured to output “limited” video in therange 16-235. The display will expand the video from the range 16-235 to 0-255 internally.The video range used by the Compute Module depends on the Operating System. By default anddepending on the OS, many distributions will automatically output a video signal to the display that usesvideo levels 16 to 235. A configuration file or menu setting is used to configure the video level. See “Table5-1: Operating System Distro” for details about each OS.For Raspbian and many other OS distros, the current video settings can be confirmed by typing thefollowing into a terminal window:tvservice –sThe output should show something similar to the following:“HDMI CEA (16) RGB lim 16:9, 1920x1080 @ 60.00 Hz, progressive”If “lim” is shown, it means that limited 16 – 235 video is being output to the display.To change this setting, a configuration file must be edited. If changing the setting from the ComputeModule itself, use the built in text editor “Nano” to edit the config.txt file:sudo nano /boot/config.txtScroll to the end of the file and enter the following line:hdmi_pixel_encoding=2Save the file by pressing CONTROL + o then ENTERExit Nano by pressing CONTROL + xRestart the Compute Module by typing:sudo rebootWhen rebooted, confirm the video levels are correct by using the following command again:tvservice –sThe output should now show “full”“HDMI CEA (16) RGB full 16:9, 1920x1080 @ 60.00 Hz, progressive”7.2 To disable overscan (if black bars are visible on the sides of thescreen)Either• Run the Raspberry Pi Config utilitysudo raspi-configSelect: 9 Advanced Options
