<?php
declare(strict_types=1);

$image = imagecreatetruecolor(8, 6);
$white = imagecolorallocate($image, 255, 255, 255);
imagefilledrectangle($image, 4, 0, 7, 5, $white);
imageconvolution($image, [[1,1,1], [1,1,1], [1,1,1]], 9.0, 0.0);
$pixel = imagecolorsforindex($image, imagecolorat($image, 3, 2));
echo $pixel["red"], ",", $pixel["green"], ",", $pixel["blue"], "\n";
$pixel = imagecolorsforindex($image, imagecolorat($image, 4, 2));
echo $pixel["red"], ",", $pixel["green"], ",", $pixel["blue"], "\n";
