<?php

$i=imagecreatefromjpeg("photo3.jpg");//测试图片，自己定义一个，注意路径

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);

//示例：

echo $rAverage;

?>