如何调用img src中的函数

I have below code but don't want to encode the image as Base64 just link the image and get it with same function.

<img src="data:image/png;base64,'.base64_encode(file_get_contents(get_field('email_logo', 'option')['url'])).'" alt="The Domain" />

How to call the function inside img src?

If you want only the link and it's correct as it is:

<img src="'.get_field('email_logo', 'option')['url'].'"/>

You've not shown us how this bit of code connects to the PHP around it. Assuming that there is a closed PHP block before hand, rather than this appearing in a print or heredoc...

?>
...
<img src="data:image/png;base64,
  <?php 
     print base64_encode(file_get_contents(
         get_field('email_logo', 'option')['url']
         ));
  ?>'" alt="The Domain" />