// Change alt & title attributes of main product image to product name.
add_filter('wp_get_attachment_image_attributes', 'taisho_change_image_attributes', 20, 2);
function taisho_change_image_attributes($attr, $attachment) {
    global $post;
    if ($post->post_type == 'product') {
        $product = wc_get_product( $post->ID );
        $authortags = strip_tags ($product->get_tags());
        $title = $post->post_title;
        $attr['alt'] = $title .' '. $authortags;
        $attr['title'] = $title .' '. $authortags;
    }
    return $attr;
}

apply_filters( 'woocommerce_single_product_image_thumbnail_html', wc_get_gallery_image_html( $attachment_id ), $attachment_id );