Value contrast (light vs dark) is the strongest visual cue, outranking saturation and hue

Of the three dimensions of color—value, saturation, hue—value contrast (lightness versus darkness) is the most powerful. It separates figure from ground even in grayscale. Saturation contrast is secondary; hue contrast alone is the weakest. A common failure is relying solely on hue contrast: red text on green at equal value is illegible and produces a vibrating edge. The hierarchy is value > saturation > hue. Simultaneous contrast compounds this: a gray tone’s perceived lightness shifts with its surround, so a neutral can read warm on blue or cool on orange.

Examples

Red text on a green background of equal brightness reads as noise; changing to dark text on a light ground makes it instantly legible even in grayscale.

Assessment

Rank the three contrast dimensions in order of visual power. Given a red-on-green element that vibrates, explain the fix without changing any hue.