利用PHP和GD库实现图片马赛克效果的最佳实践

// 创建一个JPEG图像资源
$image = imagecreatefromjpeg('original_image.jpg');

// 获取原始图像的宽度和高度
$width = imagesx($image);
$height = imagesy($image);

// 定义每个小方块的大小
$blockSize = 10;

// 处理每个小方块
for ($y = 0; $y < $height; $y += $blockSize) {
    for ($x = 0; $x < $width; $x += $blockSize) {
        $colors = [];

        // 获取当前小方块内的颜色
        for ($blockY = $y; $blockY < $y + $blockSize; $blockY++) {
            for ($blockX = $x; $blockX < $x + $blockSize; $blockX++) {
                $rgb = imagecolorat($image, $blockX, $blockY);
                $colors[] = imagecolorsforindex($image, $rgb);
            }
        }

        // 计算平均颜色
        $avgRed = 0;
        $avgGreen = 0;
        $avgBlue = 0;
        $totalPixels = count($colors);

        foreach ($colors as $color) {
            $avgRed += $color['red'];
            $avgGreen += $color['green'];
            $avgBlue += $color['blue'];
        }

        $avgRed = round($avgRed / $totalPixels);
        $avgGreen = round($avgGreen / $totalPixels);
        $avgBlue = round($avgBlue / $totalPixels);

        $avgColor = imagecolorallocate($image, $avgRed, $avgGreen, $avgBlue);

        // 替换小方块为平均颜色
        imagefilledrectangle($image, $x, $y, $x + $blockSize, $y + $blockSize, $avgColor);
    }
}

// 保存马赛克效果图像
imagejpeg($image, 'mosaic_image.jpg');

// 输出马赛克效果图像到浏览器
header('Content-type: image/jpeg');
imagejpeg($image);

// 释放资源
imagedestroy($image);