Script to convert PNG image to white

convert_png_to_white.sh

#!/usr/bin/env bash
#
## Converts png image to white using the "convert" utility from imagemagick
#
# MIT No Attribution
#
# Copyright 2024 Betsalel "Saul" Williamson
#
# Permission is hereby granted, free of charge, to any person obtaining a copy of this
# software and associated documentation files (the "Software"), to deal in the Software
# without restriction, including without limitation the rights to use, copy, modify,
# merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
# INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
# PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#######################################################################################

# get filename and extension 
base_filename=$(basename -- "$1")
filename="${base_filename%.*}"

# get extension
extension="${base_filename##*.}"
extension_upper=$(echo -n ${extension} | tr '[:lower:]' '[:upper:]')

case $extension_upper in
  PNG)
    convert "$1" -fill white -colorize 100 "${filename}_white.png"
    ;;
  *)
    >&2 echo "ERROR: File must have png extension"
    exit 1
    ;;
esac