How can I add image size for header_image() just like featured image by using add_image_size()
What is the correct way of adding image size for header_image()
This may can help you
add_theme_support( 'post-thumbnails', array( 'post' ,'promotions',
'services', 'counter') );
set_post_thumbnail_size( 200, 200, true );
add_image_size( 'slider-image', true );
Image will resize according to your html code