<?php

// Array of custom image sizes to add
$my_image_sizes = array(
	array( 'name'=>'slideshow-full', 'width'=>544, 'height'=>380, 'crop'=>true ),
	array( 'name'=>'slideshow-thumb', 'width'=>30, 'height'=>30, 'crop'=>true ),
	array( 'name'=>'attraction-thumb', 'width'=>67, 'height'=>67, 'crop'=>false ),
);

// For each new image size, run add_image_size() and update_option() to add the necessary info. 
// update_option() is good because it only updates the database if the value has changed. It also adds the option if it doesn't exist
foreach ( $my_image_sizes as $my_image_size ){
	add_image_size( $my_image_size['name'], $my_image_size['width'], $my_image_size['height'], $my_image_size['crop'] ); 
	update_option( $my_image_size['name']."_size_w", $my_image_size['width'] );
	update_option( $my_image_size['name']."_size_h", $my_image_size['height'] );
	update_option( $my_image_size['name']."_crop", $my_image_size['crop'] );
}

// Hook into the 'intermediate_image_sizes' filter used by image-edit.php. 
// This adds the custom sizes into the array of sizes it uses when editing/saving images. 
add_filter( 'intermediate_image_sizes', 'my_add_image_sizes' );
function my_add_image_sizes( $sizes ){
	global $my_image_sizes;
	foreach ( $my_image_sizes as $my_image_size ){
		$sizes[] = $my_image_size['name'];
	}
	return $sizes;
}

?>