if 0 {[Richard Suchenwirth] 2004-08-18 - From [http://worldtimezone.com/] I had
obtained some GIF images that together form a map of the world's time
zones, such that 3 rows of 3 GIF images each make the whole picture. I
wanted to re-compose them into one image, and so I wrote this code,
which takes a list of lists (one per row) of filenames, and pastes them
together, according to this specification,
into one big [photo] image, which is returned to the caller. Easy enough.
The following code worked on my test case - feel free to try it on others! :}
 proc image'compose filenames {
    set img [image create photo]
    set x 0
    set y 0
    foreach row $filenames {
        foreach file $row {
            set tmp [image create photo -file $file]
            $img copy $tmp -to $x $y
            incr x [image width $tmp]
            image delete $tmp
        }
        set x 0
        set y [image height $img]
    }
    set img
 }
if 0 {
----
[Category Image processing] | [Arts and crafts of Tcl-Tk programming]
}