Pictures: <?php echo CHV\DB::queryFetchSingle("SELECT COUNT(*) as total FROM " . CHV\DB::getTable('images'))['total']; ?><br/>
Albums: <?php echo CHV\DB::queryFetchSingle("SELECT COUNT(*) as total FROM " . CHV\DB::getTable('albums'))['total']; ?><br/>
Users: <?php echo CHV\DB::queryFetchSingle("SELECT COUNT(*) as total FROM " . CHV\DB::getTable('users'))['total']; ?><br/>
If it helps, for version 3.7.0 I'm adding a lot of triggers and automatic counters for almost everything (user likes, user content views, etc.) so I will add counts for the total images, albums and users so you won't need to perform that count query which could be slow if you host millions of images.