Get dominant color from an Imagick image

getDominantColor.php

<?php

/**
 * Two methods to get the dominant color from an image.
 * Useful to create placeholders while loading an image.
 *
 * Method 1 yields more bright colors than method 2.
 */

/**
 * Method 1, using average R,G,B values from image channel statistics.
 */
function getDominantColor1(Imagick $imagick): string
{
    /** @var int $quantumRange */
    $quantumRange = $imagick::getQuantumRange()['quantumRangeLong'];

    /** @psalm-var array<Imagick::CHANNEL_*, array{mean: float}> $channelStats */
    $channelStats = $imagick->getImageChannelStatistics();

    $getValue = function(int $channel) use ($quantumRange, $channelStats): int {
        $mean = $channelStats[$channel]['mean'];
        $mean = (int) round($mean / $quantumRange * 255);

        assert($mean >= 0 && $mean <= 255);

        return $mean;
    };

    $r = $getValue(Imagick::CHANNEL_RED);
    $g = $getValue(Imagick::CHANNEL_GREEN);
    $b = $getValue(Imagick::CHANNEL_BLUE);

    return sprintf('%02x%02x%02x', $r, $g, $b);
}

/**
 * Method 2, using quantizeImage().
 *
 * Adapted from https://manu.ninja/dominant-colors-for-lazy-loading-images/
 */
function getDominantColor2(Imagick $imagick): string
{
    $imagick = clone $imagick;

    $imagick->resizeImage(250, 250, Imagick::FILTER_GAUSSIAN, 1);
    $imagick->quantizeImage(1, Imagick::COLORSPACE_RGB, 0, false, false);

    $color = $imagick->getImagePixelColor(0, 0)->getColor(true);

    $r = (int) round($color['r'] * 255.0);
    $g = (int) round($color['g'] * 255.0);
    $b = (int) round($color['b'] * 255.0);

    return sprintf('%02x%02x%02x', $r, $g, $b);
}