Colour
- Chromatic colour is hue, the normal meaning of the word, and has strong cultural implications, such as red meaning OK or Lucky in China; people's colour perceptions vary widely, so one can't rely on it. For black and white viewers, the green ball is next to the pink.
- Typographic colour is the lightness or darkness of a block of text. It could be measured as the ratio of black pixels to white ones. Perhaps because of the variations of night, dusk and day, the human eye is every sensitive to shade.
- Therefore, use line spacing and type size to control colour, but try not to vary it without reason.