meme captions using imagemagick

caption.sh

#!/bin/bash

in=$1
text=$2
out=$3

if [ $# -lt 3 ]; then
    exit
fi


font="Futura PT Cond Extra Bold"
width=$(identify -format %w ${in})
height=$(( width - ((width / 25) * 2 ) ))
fontsize=$(( width / 13 ))

convert \
    -size "${width}x${height}" \
    -background "white" \
    -fill "black" \
    -font "${font}" \
    -pointsize "${fontsize}" \
    \( -gravity "center" pango:"<span font_family=\"${font}\" weight=\"bold\">${text}</span>" \
    -gravity "north" -extent "${width}x$(( 2 * fontsize ))" \) \
    "${in}" -append \
"${out}"