mk_polaroid_stack()
{
    local stackfiles=( "$@" )
    local CONVERT="convert -quality 01"

    # this assignment not used in script, just for standalone demo purposes
    WORK_DIR=`pwd`

    for i in ${!stackfiles[@]}; do

        # Use a 'random' angle
        local angle=$((RANDOM %45 +1))
        local angle=$(( (angle / 2) * 2 ))

        # thumbnail to 120x80 (just dvd for now) TODO get rid of magic numbers
        $CONVERT "${stackfiles[i]}" -background none -thumbnail 120x80\! \
        -bordercolor '#EAEAEA' -shave 4x4 +repage -border 4x4 \
        -rotate $angle  "$WORK_DIR/tnail${i%.*}.png"
        stack_files[i]=$WORK_DIR/tnail${i%.*}.png

        # Composite the polaroid over the canvas

        # get 'random' coordinates
        local rand_xloc=$((RANDOM %400 +80))
        local rand_yloc=$((RANDOM %200 +50))
        local rand_loc="+${rand_xloc}+${rand_yloc}"
        local img_page[i]="-page $rand_loc"
    done
    for i in ${!stack_files[@]}; do
        local image_page=( "${image_page[@]}" ${img_page[i]} "${stack_files[i]}" )
    done
    $CONVERT -background none -size 640x480 xc:none \
    "${image_page[@]}" -mosaic -trim +repage miff:- |
    $CONVERT -size 720x480 xc:black -background none \
    -gravity Center -geometry +0+0 - -composite \
    "$WORK_DIR/image_stack.png"
}