I'd really encourage you to use a site such as http://www.lagom.nl/lcd-test/ (the first that came up in a search, not necessarily a recommendation of this as the best service) to get some test patterns so you can check the brightness/contrast/etc settings of your TV.
Different settings will be displayed depending on what settings level you have selected within Kodi (see the bottom left of the screenshot I provided). My screenshot has 'Expert' settings enabled so will display all possible options. If you have a lower level selected, you will have less options displayed.
Edit: It's also worth saying that the skin isn't developed on an OSMC device, so it's possible that there will be some options native to the device used (a MacOS device) that aren't applicable to an OSMC device such an a RaspberryPi or a Vero device. The fact that different options are displayed, though, doesn't affect the visibility of the options that are displayed.