ผมอยากขอคำปรึกษาเกี่ยวกับ Image Processing การเปรียบเทียบรูป แล้วคิดออกมาเป็น%

<?php
error_reporting(E_ERROR);
$source_file = './img/cartoon1.jpg';
$maxheight = 300;
$barwidth = 2;

$im = imagecreatefromjpeg($source_file);

$imgw = imagesx($im);
$imgh = imagesy($im);

// n = total number or pixels

$n = $imgw * $imgh;

$histo = array();

for ($i = 0; $i < $imgw; $i++) {
    for ($j = 0; $j < $imgh; $j++) {

        // get the rgb value for current pixel
        $rgb = imagecolorat($im, $i, $j);
        // extract each value for r, g, b
        $r = ($rgb >> 16) & 0xFF;
        $g = ($rgb >> 8) & 0xFF;
        $b = $rgb & 0xFF;
        // get the Value from the RGB value
        $V = round(($r + $g + $b) / 3);
        // add the point to the histogram
        $histo[$V] += $V / $n;
    }
}

// find the maximum in the histogram in order to display a normated graph
$max = 0;
for ($i = 0; $i < 255; $i++) {
    if ($histo[$i] > $max) {
        $max = $histo[$i];
    }
}
echo "<div style='width: " . (256 * $barwidth) . "px; border: 1px solid'>";
for ($i = 0; $i < 255; $i++) {
    $val += $histo[$i];

    $h = ( $histo[$i] / $max ) * $maxheight;

    echo "<img src=\"./img.gif\" width=\"" . $barwidth . "\"
height=\"" . $h . "\" border=\"0\">";
}
echo "</div>";
?>