Using background images formatter for taxonomy in views
If you have not disabled Add default classes under Style Settings of image field then you can use views_field_FIELD_MACHINE_NAME class to play with css. 

For example If you have a field with machine name field_book_category_icon then after adding this field to your view you can get a class views-field-field-book-category-icon on front end when ever you render that view on your page.