Why is the resolution of the image generated by PHP GD library 96? How to change it to 72

For a long time , On the Internet, you can change the soup without changing the medicine , At last , take , You're welcome
Official website address ：https://www.php.net/manual/zh/function.imageresolution.php
 

$newImg = imagecreatetruecolor($newWidth, $newHeight);
imageresolution($newImg, 72, 72);
...
imagepng($newImg, $output_file_name);