When I click the AddThis Pinterest button, the box opens mid-screen, offereing a variety of images from my page. Cool. However, among those offered are grainy, enlarged po
AddThis Pinterest has support for "at_include" and "at_exclude" classes for images.
Full post here: http://support.addthis.com/customer/portal/articles/1300322-pinterest-image-sharing#.UuAnmrvTm2x
Include Images
You can instruct the share preview to only grab specific images from the page by using the “image_include” configuration option. First, set image_include to your desired class name (id selectors are not allowed, only class selectors), then add that same class name to each of the images on the page that should be grabbed. For image_include, don’t add the ‘.’ selector. Here’s an example: