RGB444 の色を全部使うだけの画像

depth4colortable.php

<?php
ini_set("memory_limit", '2G');

$nPixels = pow(2, 4 + 4 + 4);

$width = (int) sqrt($nPixels);
$height = $nPixels /$width;

$im = imagecreatetruecolor($width, $height);
if (! $im) {
   echo "im is false";
   exit (1);
}

$x = 0;
$y = 0;
for ($r = 0 ; $r < 0x100 ; $r+=0x11) {
    // echo "r:$r\n";
    for ($g = 0 ; $g < 0x100 ; $g+=0x11) {
        // echo "g:$g\n";
        for ($b = 0 ; $b < 0x100 ; $b+=0x11) {
            // echo "b:$b\n";
            $c =  imagecolorallocate($im, $r, $g, $b);
            imagesetpixel($im, $x, $y, $c);
            $x++;
            if ($width <= $x) {
                $x = 0;
                $y++;
            }
        }
    }
}
imagepng($im);