[[...]] 















[BLT] (?)
and [Xbit] support tiled images.
With the latter,
    set tiled_image [image create gimg tiledImage -file image_file_name -tile 1]
can be used anywhere that a conventional [Tk] image is valid
(true?).






----
Saverio Castellano offers, 
    proc SetTiledBackground {cv img} {
      set h [image height $img]
      set w [image width $img]
      set width [$cv cget -width]
      set height [$cv cget -height]
      set row [expr $h/2]
      set col [expr $w/2]

      while {$row<$height} {
        set col [expr $w/2]
        while {$col<$width} {
           $cv create image $col $row -image $img
           incr col $w
        }
        incr row $h
      }
    }