php检测图片主要颜色的方法

$i = imagecreatefromjpeg("image.jpg");
for ($x=0;$x<imagesx($i);$x++) {
  for ($y=0;$y<imagesy($i);$y++) {
    $rgb = imagecolorat($i,$x,$y);
    $r  = ($rgb >> 16) & 0xff;
    $g  = ($rgb >> & 0xff;
    $b  = $rgb & 0xff;
    $rtotal += $r;
    $gtotal += $g;
    $btotal += $b;
    $total++;
  }
}
$raverage = round($rtotal/$total);
$gaverage = round($gtotal/$total);
$baverage = round($btotal/$total);