set image comment to labels detected via AWS

tagImages.sh

#!/bin/sh

MAXLABELCOUNT=4
MINCONFIDENCE=90

mkdir smallpics

# create smaller versions, that are both small and big enough for image recognition
parallel convert {} -resize 2048x2048 -quality 90 smallpics/{} ::: *.jpg

cd smallpics
for i in *.jpg; do 
  # fetch the labels from aws.
  # the CLI's user has to have access to the rekognition API
  aws rekognition detect-labels --image-bytes fileb://$i >> $i.labels.json; 

  # collect at most MAXLABELCOUNT comments with a set MINCONFIDENCE
  comment=""
  for ((labelIndex=0; labelIndex<MAXLABELCOUNT;labelIndex++)); do
    confidence=`jq ".Labels[$labelIndex].Confidence" $i.labels.json`
    if [ `echo $confidence'>'$MINCONFIDENCE | bc` -eq 1 ]
    then
      label=`jq ".Labels[$labelIndex].Name" $i.labels.json`
      comment=$comment' '`echo $label | sed -e 's/"//g'`
    fi
  done

  exiv2 -M"set Exif.Photo.UserComment charset=Ascii $comment" ../$i
done