Images

http://codex.wordpress.org/Function_Reference/add_image_size

Notes

  • Using the ‘false’ setting will fail to produce a new image in the upload directory if one of the image dimensions of the uploaded image are equal to the new image size.
  • If a registered image size is removed from functions.php, then any image uploaded before that point and then deleted from the media library afterwards, does not have those auto-generated sizes deleted too. Only image sizes that exist in functions.php are deleted.