How to load external images in PHP drawing, _PHP tutorial

//1. Create canvas
$im = imagecreatetruecolor(300,200);//Create a new true color image, the default background is black, and return the image identifier. There is also a function imagecreate that has been deprecated.
//2. Load external images
$im_new = imagecreatefromjpeg("baidu.jpg");//Return image identifier
$im_new_info = getimagesize("baidu.jpg");//Get the image size and return an array. This function does not require the use of the gd library.
/*----
****3. Copy the loaded image to the canvas
****Parameter description:
$im: Needless to say, it refers to the canvas;
$im_new: Source image, which is an image loaded from outside
(30,30): Place the loaded image in the canvas, upper left corner
(0,0): Indicates where the loaded image starts. (0,0) represents the starting point of the upper left corner, you can also load only part of the image
(*,*): Represented by *, it can be the width and height of the original image, or it can be smaller than the width and height. Only a part is intercepted and used together with the above coordinates to indicate the intercepted part
******/
imagecopy($im,$im_new,30,30,0,0,$im_new_info[0],$im_new_info[1]);//Return Boolean value
//3. Output image
header("content-type: image/png");
imagepng($im);//Output to the page. If there is a second parameter [,$filename], it means saving the image
//4. Destroy the image and release memory
imagedestroy($im);
?>