La funzione da editare è featured_image_url

codice:
<a class="responsive-featured-image" href="<?php echo esc_url( get_permalink( $post->ID ) ) ?>" title="<?php echo esc_attr( get_post_field( 'post_title', $post->ID ) ) ?>">
                <img class="post-featured-image" alt="<?php the_title_attribute();?>" <?php cryout_schema_microdata( 'url' ); ?>
                src="<?php echo $featured_image_url; ?>" srcset="<?php if ($use_srcset) echo cryout_get_featured_srcset(
                        get_post_thumbnail_id( $post->ID ),
                        array(  'anima-featured',
                                'anima-featured-full',
                                'anima-featured-half',
                                'anima-featured-third' )
                        ) ?>" sizes="<?php if ($use_srcset) echo cryout_gen_featured_sizes( anima_featured_width(), $options['anima_magazinelayout'], $options['anima_landingpage'] ) ?>"/>
            </a>