"Generate image for social networks"
is a setting which enables generating preview with the post subject and author's username for the public posts you share in social networks
such as Facebook, Twitter, and VKontakte. This preview can also contain an image from the post, if there's an image larger than 600x315 pixels with aspect ratio from 0,5 to 0,8 and horizontal (landscape) orientation. If there are several images in an entry, the first image of appropriate size is used.
If there are no images in the entry or their size doesn't match the specification listed above, the preview will contain the post subject only.
The preview of LiveJournal post in other social networks is generated if the post was created or edited after 24th October 2016 by the user of an account with Professional
or Permanent package of service (or by a user with "Social capital"
indicator above 10).
To enable preview generating, please visit the Account settings page
and ensure that the checkbox "Generate image for social networks"