You can specify the dimension of any thumbnails by adding a filter to your function.php:
if ( !function_exists('theme_setup') ) :
function theme_setup() {
// Add post thumbnails (http://codex.wordpress.org/Post_Thumbnails)
add_theme_support('post-thumbnails');
add_image_size( 'one-thumb-slider', 1170, 430, true );
add_image_size( 'two-thumb-full', 900, 500, true );
add_filter( 'image_size_names_choose', 'custom_image_sizes' );
}
endif;
add_action('after_setup_theme', 'theme_setup');
Then in your loop:
<img src="<?php echo $image['sizes']['two-thumb-full']; ?>" alt="<?php echo $image['alt']; ?>" />
Note: Remember to add the filter before uploading any images otherwise you need to reset all the thumbs via a plugin or delete and re-upload all the images.
