title: Different thumbnails sizes for different custom post types, and creating thumbnails for featured images only
body: <p>I've got a wordpress site with a few custom post types. Each custom post type shows a list page, basically displaying a featured image and a title, and then you can click through to a detail page with a bunch more images.</p>
  
  <p>I only need to resize uploaded "feature images". If an uploaded image isn't used as a feature image, I don't need a thumbnail for it. Furthermore, each custom post type shows a different sized feature image.</p>
  
  <p>So, what I want to do is say:</p>
  
  <p>a) Only create thumbnails for feature images</p>
  
  <p>b) Create certain sizes for certain post types, and not for others.</p>
  
  <p>Is this possible? At the moment, EVERY uploaded image is getting 5 thumbnail sizes, and my wp-content directory is WAAAY bigger than it needs to be!</p>
  
  <p>Thanks in advance.</p>