Wordpress: how to display a different header image on each page - php

Question

I would like to show different header images on a wordpress site using php. Although I found numerous subjects with the title of my question, none of them clearly explain how this is done.
The first one I tried just failed to work. Here is the code I added to functions.php. I know the file is executed since the text I added is displayed.
//12/28/2020 - START
define("HOME", "http://johnm5.sgedu.site/wp-content/uploads/2020/12/nyc-e1608682430748.png");
define("AWARD", "http://johnm5.sgedu.site/wp-content/uploads/2020/12/trophy-e1608681301876.jpg");
define("ERP", "http://johnm5.sgedu.site/wp-content/uploads/2020/12/IntuitiveERP-e1608681626647.png");
define("EVENT", "http://johnm5.sgedu.site/wp-content/uploads/2020/12/Calendar-scaled-e1608681638194.jpg");
function change_the_header($url_for_image) {
if (is_home())
$url_for_image = HOME;
else if (is_single())
$url_for_image = ERP;
else
$url_for_image = AWARD;
return $url_for_image;
}
add_filter('theme_mod_header_image', 'change_the_header');
//12/28/2020 - END
This one doesn't explain where the code goes nor how the function is_page works. I tried to fill in the blanks, but it failed in the end.
//12/28/2020 - START
if( is_page('About') ) echo HOME;
elseif( is_page('Events') ) echo EVENT;
elseif( is_page('Awards') ) echo AWARD;
else echo '-NONE-';
//12/28/2020 - END
With one answer by someone who knows nothing of Wordpress and no mention of which file is being edited, I didn't even attempt this.
With code that actually ran, I had the most hope here. However, there is no explanation given on how to determine what page you are on. There is no is_about function nor is there any information on what is required of one so I can create it. And once I have it, there is nothing to indicate where it goes. Also passing a parameter to get_header does nothing.
//12/28/2020 - START
//12/28/2020 - OLD
//get_header();
//12/28/2020 - NEW
if (is_home()) {
echo '* HOME *';
get_header();
//} else if (is_about()) {
// echo '# away #';
// get_header('About');
} else {
echo '# away #';
get_header('About');
}
wp_head();
//12/28/2020 - END

Answer 1

I figured it out: The id can be found in the body tag or in your browser when using wordpress to edit pages, it will be the post id.
in the following link the page id is 62:
johnm5.sgedu.site/wp-admin/post.php?post=62&action=edit
Here's my code:
//JPM - 12/28/2020 - START
define("ABOUT_ID", 6);
define("AWARD_ID", 64);
define("ERP_ID", 58);
define("EVENT_ID", 62);
define("ABOUT", "http://johnm5.sgedu.site/wp-content/uploads/2020/12/nyc-e1608682430748.png");//68
define("AWARD", "http://johnm5.sgedu.site/wp-content/uploads/2020/12/trophy-e1608681301876.jpg");//64
define("ERP", "http://johnm5.sgedu.site/wp-content/uploads/2020/12/IntuitiveERP-e1608681626647.png");//58
define("EVENT", "http://johnm5.sgedu.site/wp-content/uploads/2020/12/Calendar-scaled-e1608681638194.jpg");//62
function change_the_header($url_for_image) {
if (is_page(ABOUT_ID)) {
$url_for_image = ABOUT;
} else if (is_page(AWARD_ID)) {
$url_for_image = AWARD;
} else if (is_page(ERP_ID)) {
$url_for_image = ERP;
} else if (is_page(EVENT_ID)) {
$url_for_image = EVENT;
}
else {
echo "<script>alert('- NONE -');</script>";
}
return $url_for_image;
}
add_filter('theme_mod_header_image', 'change_the_header');