Dear John Huebner.
Thank you for your quick reply.
It works fine as below.
in functions.php
function my_acf_modify_img_field($field) {
if(get_post_type() === 'Post Type A') {
$field['preview_size'] = 'preview_for_A';
} elseif(get_post_type() === 'Post Type B') {
$field['preview_size'] = 'preview_for_B';
}
return $field;
}
add_filter('acf/prepare_field/name=cf_my_img', 'my_acf_modify_img_field');
I deeply appreciate you.
