Function for creating Identicons.

uniqueImage.php

<?php
/**
 * Generate a unique Image based on a input string
 * @param string $data 
 * @return string A SVG image
 */
function unique_img(string $data, string $background = "#000"): string
{
    $hash = hash("sha512", $data);
    $svg_data = '<rect x="0" y="0" width="128" height="128"  fill="' . $background . '" />';
    for ($i = 0; $i < 8; $i++) {
        for ($i1 = 0; $i1 < 8; $i1++) {
            if ($i % 2 == 0) {
                if ($i1 % 2 == 0) {
                    $r = hexdec(substr($hash, ($i + 1) * ($i1 + 1), 1)) * 0.5;
                } else {
                    $r = hexdec(substr($hash, ($i + 1) * ($i1 + 1), 1)) * 0.75;
                }
            } else {
                if ($i1 % 2 == 0) {
                    $r = hexdec(substr($hash, ($i + 1) * ($i1 + 1), 1)) * 0.75;
                } else {
                    $r = hexdec(substr($hash, ($i + 1) * ($i1 + 1), 1)) * 0.5;
                }
            }
            $svg_data .= '<circle cx="' . (8 + 16 * $i1) . '" cy="' . (8 + 16 * $i) . '" r="' . $r . '" />';
        }
    }
    $svg_color = 'hsl(' . round(hexdec(substr($hash, 0, 2)) * 1.40625) . ', 100%, 50%)';
    return '<?xml version="1.0" encoding="utf-8"?>' . "\n" . '<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"  width="128" height="128" fill="' . $svg_color . '">' . $svg_data . '</svg>';
}