file-corresponder.sh

#!/bin/bash

for name in *.png; do
  if ! test -f "${name%.*}.json"
  then
    echo "$name"
  fi
done

# To run this script - 
# 1. Creat a file called file-corresponder.sh in the working directory 
# 2. run the command in terminal - chmod +x file-corresponder.sh
# 3. run the script in terminal with command - ./file-corresponder.sh
# 4. The printed out png files are missing a corresponding .json file.