Prior to Backdrop 1.8.0, calls to
theme('image', $variables) required that the path to an image be specified using
$variables['uri']. This was confusing because both URIs like
public://example.png and paths like
core/favicon.ico were allowed. Backdrop now accepts either "path" or "uri" properties. This makes porting modules from Drupal 7 easier, as it only supported the "path" property.
Backdrop 1.7 and earlier:
Backdrop 1.8 and later: