Override Schema media image with an attachment id from post meta https://schema.press

schema-wp-override-media.php

<?php //* do not include php tag

add_filter( 'schema_wp_filter_media', 'schema_wp_override_media_with_image_attachment_id_post_meta_716235' );
/**
 * Override media image with an attachment id from post meta
 *
 * @param array $media.
 * @since 1.5
 * @return array contains the image attributes
 */
function schema_wp_override_media_with_image_attachment_id_post_meta_716235( $media ) {
	
	global $post;
	
	// Get attachmemnt id from post meta
	//
	// Note: replace ATTACHMENT_ID_POST_META_KEY with the actual post meta key you use to save attachment id value
	//
	$attachment_id		= get_post_meta( $post->ID, 'ATTACHMENT_ID_POST_META_KEY', true);
	
	// Get image attributes
	$image_attributes	= wp_get_attachment_image_src( $attachment_id, 'full' );
	
	// Get image other details
	$image_url			= $image_attributes[0];
	$image_width		= ( $image_attributes[1] > 696 ) ? $image_attributes[1] : 696; // Images should be at least 696 pixels wide
	$image_height		= $image_attributes[2];
	
	// Build our media array
	$media = array (
		'@type' 	=> 'ImageObject',
		'url' 		=> $image_url,
		'width' 	=> $image_width,
		'height' 	=> $image_height,
		);
		
	return $media;
}