I do a bit of amateur astronomy when I have time, and a smartphone is a nice accessory to have along. The display, however, does not play well with night vision. Apps designed for this purpose often have all-red, monochrome displays to counter this problem, but switching back to another app can wipe that out in an instant.
Is there some way to fiddle with the OS so it always converts the device's display to a monochrome setting, regardless of what any given app is trying to paint? Allowing 0-255 red, with both the green and blue components clamped to zero is what I'm after, although allowing for further adjustment might be helpful as well, if any such thing is possible.