我有PHP代码修剪白色外边框并调整大小。当我使用imagejpeg（$ newImage）输出它时，浏览器工作正常但是当我尝试保存到使用imagejpeg（$ newImage，'test.jpg'）时，它不会被保存到任何地方。请帮忙吗？
$im = imagecreatefromjpeg($src);
$bg = imagecolorallocate($im,$rgb,$rgb,$rgb);
// Set the header and output image.
header('Content-type: image/jpeg');
imagetrim($im,$bg);
$width = imagesx($im);
$height = imagesy($im);
$newHeight = $height * $newWidth/$width;
$newImage = imagecreatetruecolor($newWidth, $newHeight);
imagecopyresampled($newImage, $im, 0, 0, 0, 0, $newWidth, $newHeight, $width, $height);
//imagejpeg($newImage);
//header('Content-Type: image/jpeg');
imagejpeg($newImage, 'test.jpg');
imagejpeg($newImage);
imagedestroy($im);
imagedestroy($newImage);