#!/bin/sh

# usage:   $0 scalefactor in.image out.jpeg
# example: $0 0.2 bigimage.png thumb.jpeg

gimp -i -b "
  (begin
    (define factor $1)
    (define image (car (gimp-file-load 1 \"$2\" \"$2\")))
    (gimp-image-scale image
                      (* (car (gimp-image-width  image)) factor)
                      (* (car (gimp-image-height image)) factor))
    (file-jpeg-save 1 image (car (gimp-image-get-active-drawable image))
                    \"$3\" \"$3\" 0.80 0.10 1 0 \"$4\" 0 1 0 2)
    (gimp-quit 0))"