Script to generate QR code with data, and then place an overlay image on top of it

qrencode-overlay.sh

#!/bin/bash

if [ "$#" -eq "0" ] ; then
  printf "Usage: %s [content] [overlay image] [output image]\n" "$0"
  exit 1
fi

content="$1"
overlayImage="$2"
outputImage="$3"
outputFilename=$(basename "${outputImage}")
qrencode --level=H --size=20 --output="/tmp/${outputFilename}" "${content}"
outputImageSize=$(identify -format "%w" "/tmp/${outputFilename}")

originalOverlayImageWidth=$(identify -format "%w" "${overlayImage}")
originalOverlayImageHeight=$(identify -format "%h" "${overlayImage}")
overlayImageWidth=$(( ${outputImageSize} / 3 ))
scaleFactor=$(echo "scale=2 ; ${overlayImageWidth} / ${originalOverlayImageWidth}" | bc -q)
overlayImageHeight=$(echo "scale=2 ; ${scaleFactor} * ${originalOverlayImageHeight}" | bc -q | cut -d '.' -f 1)

convert "${overlayImage}" -resize "${overlayImageWidth}x${overlayImageHeight}" "/tmp/overlay-resized.png"
composite -gravity center "/tmp/overlay-resized.png" "/tmp/${outputImage}" "${outputImage}"