(define (batch-indexed-14c filemask)
  (let* ((filelist (cadr (file-glob filemask 1))))
    (while filelist
           (let* ((filename (car filelist))
                  (image (car (gimp-file-load RUN-NONINTERACTIVE
                                              filename filename)))
                  (drawable (car (gimp-image-get-active-layer image))))
             (gimp-image-convert-indexed image 1 0 14 0 0 "blabla")
             (gimp-file-save RUN-NONINTERACTIVE
                             image drawable filename filename)
             (gimp-image-delete image))
           (set! filelist (cdr filelist)))))