Build color harmonies

Choose a harmony when a palette needs an explicit geometric hue relationship. Use it as a starting structure, then decide lightness, chroma, semantic roles, gamut, and contrast separately.

Choose geometry from the number of roles

Relationship	Useful starting point	Main risk
Complementary	Two opposing roles	Visual competition
Analogous	Related surfaces or categories	Insufficient separation
Split complementary	One anchor plus two softer opponents	Uneven prominence
Triadic	Three distinct families	Contrast and hierarchy still vary
Tetradic	Four families or paired opposites	Too many equal accents

Harmony methods belong to color objects rather than ColorPalette. They rotate hue in Oklch and return colors in the same concrete space as the source.

Generate the selected relationship

use PhpColor\Color\Color;
use PhpColor\Color\Palette\ColorPalette;

$base = Color::parse('#3b82f6');
$harmony = ColorPalette::scale($base->triadic());

foreach ($harmony as $color) {
    echo $color->toHex();
}

Available methods are:

Method	Returned colors
`complementary()`	One color rotated by 180 degrees
`analogous()`	The source, then colors alternating by +30 and -30 degrees
`splitComplementary()`	The source, +150 degrees, and +210 degrees
`triadic()`	The source, +120 degrees, and +240 degrees
`tetradic()`	The source, +90, +180, and +270 degrees

analogous(int $count = 2) returns the source plus the requested number of neighbors. A count below one returns an empty array:

use PhpColor\Color\Color;

$five = Color::parse('#3b82f6')->analogous(4);

echo count($five);

The output is 5.

Verify the roles after generation

These methods encode geometric hue relationships, not a guarantee of accessible contrast, in-gamut output, or equal visual prominence. Validate generated colors for the target gamut and use Contrast and accessibility for foreground/background decisions.

Use harmony detection to describe an existing palette and harmony repair to realign one; neither replaces semantic review. Continue with Detect a palette harmony, Repair a triadic palette, or Generate color harmonies.