Set default images sizes WooCommerce

functions.php

<?php
//* Do NOT include the opening PHP tag

add_action( 'after_switch_theme', 'wpstudio_woocommerce_image_dimensions', 1 );
function wpstudio_woocommerce_image_dimensions() {
	global $pagenow;

	if ( ! isset( $_GET['activated'] ) || $pagenow != 'themes.php' ) {
		return;
	}
  	$catalog = array(
		'width' 	=> '400',	// px
		'height'	=> '400',	// px
		'crop'		=> 1 		// true
	);
	$single = array(
		'width' 	=> '600',	// px
		'height'	=> '600',	// px
		'crop'		=> 1 		// true
	);
	$thumbnail = array(
		'width' 	=> '300',	// px
		'height'	=> '300',	// px
		'crop'		=> 1		// false
	);
	// Image sizes
	update_option( 'shop_catalog_image_size', $catalog ); 		// Product category thumbs
	update_option( 'shop_single_image_size', $single ); 		// Single product image
	update_option( 'shop_thumbnail_image_size', $thumbnail ); 	// Image gallery thumbs
}