New filter for adding image sizes to WP Media lightbox

image_size_names_choose.php

<?php

function cfcp_image_size_input_fields_sizes($sizes) {
	$sizes['medium-img'] = 'Content Width';
	$sizes['banner-img'] = 'Content Width Short (Cropped)';
	$sizes['large-img'] = 'Full Width';
	return $sizes;
}
add_filter('image_size_names_choose', 'cfcp_image_size_input_fields_sizes');