<?php $img = imageCreateTrueColor(400, 350); header('Content-Type:image/jpeg'); imagejpeg($img, NULl, 100); ?> If you comment out the header, the image characters will be displayed
If you remove the comments, this appears: 
This code was written off from the video of the lesson, the author has a small black rectangle on a white background, I have everything in turn.
And when this black background appears, the title changes to the contents of the address bar.
Version php 7
NULl, 100- Let's say Pie