php生成图片是乱码

header('Content-Type: image/png');
$image = imagecreatetruecolor(100, 100);
$text_color = imagecolorallocate($image, 255, 255, 255);
$text = 'Hello, World!';
imagestring($image, 5, 20, 20, $text, $text_color);
imagepng($image);
imagedestroy($image);

$image = imagecreatefromjpeg('input.jpg');
$text_color = imagecolorallocate($image, 255, 255, 255);
$text = 'Hello, World!';
imagestring($image, 5, 20, 20, $text, $text_color);
$image_path = 'output.jpg';
if (imagejpeg($image, $image_path, 100)) {
    echo 'Image saved successfully.';
} else {
    echo 'Failed to save image.';
}
imagedestroy($image);

$image = imagecreatetruecolor(100, 100);
header('Content-Type: image/png');
imagepng($image);
imagedestroy($image);