<?php

$image = 'logo.png';

$meta = getimagesize($image);
$x_size = $meta[0];
$y_size = $meta[1];
$img = imagecreatefrompng($image);

for ($y = 0; $y < $y_size; $y++) {
    for ($x = 0; $x < $x_size; $x++) {
        $rgb = imagecolorat($img, $x, $y);
        $r = ($rgb >> 16) & 0xFF;
        $g = ($rgb >> 8) & 0xFF;
        $b = $rgb & 0xFF;
        echo "[$x, $y] = rgb($r, $g, $b) \n";
    }
}