With screen types aside (backlit LCD, OLED, matte, glossy, etc...), what color scheme provides the most readability in direct sunlight?
I have not been able to find much on this in a day of Googling. The Kindle uses black on grey. I've seen light grey used on black for some mobile apps claiming good sunlight readability. With how prolific mobile apps are, I am surprised that there is not more on this subject within easy searching distance.
I went so far as to make a bunch of test swatches in paint and go outside and flip through them. It is mostly cloudy outside today so it wasn't direct sunlight but, from that quick subjective test Black on White was the best with White on Black, Black on Yellow and Black on Light Grey still pretty readable.