[Plugin: Taxonomy Images] Use Taxonomy Image On single.php

I am trying to associate an image to each term as a background image using an inline style, on the taxonomy.php it is no problem because I can use $image_url = apply_filters( 'taxonomy-images-queried-term-image-url', '', array('image_size' => 'full')
But on the single.php I am struggling to just call the url of the image, I am able to add the image associated on the page with

<?php $term = get_term_by( 'slug', get_query_var( 'term' ), get_query_var( 'taxonomy' ) ); ?>
	<?php $cats = $object_terms = wp_get_object_terms( $post->ID, 'producttype' );
foreach ( $cats as $c ) {
    $url = get_category_link( $c->term_id );
    $img = $taxonomy_images_plugin->get_image_html( 'full', $c->term_taxonomy_id );
    if( !empty( $img ) ) ?><?php echo $img ?><?Php }?>'

but I only need the image url not the <img src=”” etc./>

I am thinking that I need alter get_image_html to get_image_url or someting similar but am struggling to find any literature about this.

Any help would be appreciated

http://wordpress.org/extend/plugins/taxonomy-images/