SELECT
 ImageID,ImageName,
 Regio.RegioID,RegioName,
 Insula.InsulaID,InsulaName,
 Sources.SourceID,SourceName,
 (etc...),
 COUNT(ThemeID)
  FROM Images
    LEFT JOIN Regio ON Images.RegioID = Regio.RegioID
    LEFT JOIN Insula ON Images.InsulaID = Insula.InsulaID
    LEFT JOIN ImgThemes ON Images.ImageID = ImgThemes.ImageID
    LEFT JOIN Sources ON Images.SourceID = Sources.SourceID
    GROUP BY ImgThemes.ImageID
    ORDER BY ImageName LIMIT $start,$numrows"