<?php
declare(strict_types=1);

$image = imagecreatetruecolor(8, 6);
$white = imagecolorallocate($image, 255, 255, 255);
imagefill($image, 0, 0, $white);
$black = imagecolorallocate($image, 0, 0, 0);
imagefilledrectangle($image, 1, 1, 4, 4, $black);
$red = imagecolorallocate($image, 220, 50, 45);
imagesetpixel($image, 6, 1, $red);
ob_start(); imagepng($image); $bytes = ob_get_clean();
$payload = json_encode(["picture" => base64_encode($bytes)], JSON_THROW_ON_ERROR);
$data = json_decode($payload, true, flags: JSON_THROW_ON_ERROR);
$binary = base64_decode($data["picture"], true);
if ($binary === false) { throw new UnexpectedValueException("Invalid base64"); }
$loaded = imagecreatefromstring($binary);
echo imagesx($loaded), "\n";