php图片高斯模糊

<?php
function gaussianBlur($image, $radius) {
    $width = imagesx($image);
    $height = imagesy($image);
    $newImage = imagecreatetruecolor($width, $height);
    imagecopy($newImage, $image, 0, 0, 0, 0, $width, $height);

    for ($i = 0; $i < $radius; $i++) {
        for ($x = 0; $x < $width; $x++) {
            for ($y = 0; $y < $height; $y++) {
                $rgb = imagecolorat($image, $x, $y);
                $r = ($rgb >> 16) & 0xFF;
                $g = ($rgb >> 8) & 0xFF;
                $b = $rgb & 0xFF;

                $newR = $r;
                $newG = $g;
                $newB = $b;

                if ($x > 0) {
                    $leftRgb = imagecolorat($image, $x - 1, $y);
                    $leftR = ($leftRgb >> 16) & 0xFF;
                    $leftG = ($leftRgb >> 8) & 0xFF;
                    $leftB = $leftRgb & 0xFF;
                    $newR = ($r + $leftR) / 2;
                    $newG = ($g + $leftG) / 2;
                    $newB = ($b + $leftB) / 2;
                }

                if ($x < $width - 1) {
                    $rightRgb = imagecolorat($image, $x + 1, $y);
                    $rightR = ($rightRgb >> 16) & 0xFF;
                    $rightG = ($rightRgb >> 8) & 0xFF;
                    $rightB = $rightRgb & 0xFF;
                    $newR = ($newR + $rightR) / 2;
                    $newG = ($newG + $rightG) / 2;
                    $newB = ($newB + $rightB) / 2;
                }

                if ($y > 0) {
                    $topRgb = imagecolorat($image, $x, $y - 1);
                    $topR = ($topRgb >> 16) & 0xFF;
                    $topG = ($topRgb >> 8) & 0xFF;
                    $topB = $topRgb & 0xFF;
                    $newR = ($newR + $topR) / 2;
                    $newG = ($newG + $topG) / 2;
                    $newB = ($newB + $topB) / 2;
                }

                if ($y < $height - 1) {
                    $bottomRgb = imagecolorat($image, $x, $y + 1);
                    $bottomR = ($bottomRgb >> 16) & 0xFF;
                    $bottomG = ($bottomRgb >> 8) & 0xFF;
                    $bottomB = $bottomRgb & 0xFF;
                    $newR = ($newR + $bottomR) / 2;
                    $newG = ($newG + $bottomG) / 2;
                    $newB = ($newB + $bottomB) / 2;
                }

                $newColor = imagecolorallocate($newImage, $newR, $newG, $newB);
                imagesetpixel($newImage, $x, $y, $newColor);
            }
        }
    }

    return $newImage;
}

$image = imagecreatefromjpeg('input.jpg');
$blurredImage = gaussianBlur($image, 5);
imagejpeg($blurredImage, 'output.jpg');
imagedestroy($image);
imagedestroy($blurredImage);
?>