Change the default featured image text for a custom post type

featured-image-text.php

<?php
// Don't include opening php tage

// Change feautred image text for Portfolios
add_filter( 'post_type_labels_portfolios', 'pb_change_featured_portfolios_image_labels', 10, 1 );
function pb_change_featured_portfolios_image_labels( $labels ) {

	$new_text = __( 'Portfolio Image', 'core-functionality' );

	$labels->featured_image				= $new_text;
	$labels->set_featured_image		= 'Set '.$new_text.'';
	$labels->remove_featured_image 	= 'Remove '.$new_text.'';
	$labels->use_featured_image		= 'Use as '.$new_text.'';

	return $labels;

}