Featured images get shrunken

Hey if you want to add custom image size then add the following code in your function.php file

add_image_size( 'thumb', 220, 180, true );

and then call featured image in your template like this

<?php 
if ( has_post_thumbnail() ) { // check if the post has a Post Thumbnail assigned to it.
    the_post_thumbnail('thumb');
} 
?>

i think it will help you