How to Enable Featured Image in Thesis Theme for WordPress

On your thesis custom_function.php file, paste the below code:

//Enable Featured Image in Thesis

add_theme_support('post_thumnbails');
set_post_thumbnail_size(150,150);
add_image_size('teaser-image', 150, 150, true);
if ( function_exists( 'add_theme_support' ) )
{
add_theme_support( 'post-thumbnails' );
}
function post_image($t)
{
if ( has_post_thumbnail( $post->ID ) )
{
$image = wp_get_attachment_image_src(get_post_thumbnail_id( $post->ID), 'thumbnail' ); $t = '<a href="'.get_permalink().'"><img src="'.$image[0].'" class="imgthumb" /></a>'.$t;
}
$t = preg_replace('/<p(.*?)>/i', '<p>', $t);
return $t;
}
add_filter('the_excerpt','post_image');

You may want to tweak the appearance of your thumbnail. To do so, paste the below code in your custom.css file:

img.imgthumb {
	background-color: #EEEEEE;
	border:0.067em solid #DDDDDD; 
	float:left;
	margin:0 1.571em 0.55em 0; 
	padding:0.567em;
}