<?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, $red);
imagepng($image, "source.png");
$info = getimagesize("source.png");
$allowed = $info !== false && $info[0] > 0 && $info[1] > 0
    && $info[0] <= 1000 && $info[1] <= 1000
    && $info[0] * $info[1] <= 500000;
echo $allowed ? "size accepted\n" : "rejected\n";