convert images between formats -- uses imagemagick and heif-convert

gistfile1.txt

#!/bin/bash

# uses heif-convert: https://pypi.org/project/heif-convert/
# uses imagemagick: https://imagemagick.org/

if [ "${2}" == "" ];then
    echo "We need an output format, thanks."
    exit 99
fi

# Just a single file
if [ -f "${1}" ]; then
    echo "Converting $1 to $2 format"
    filename=$(basename -- "$1")
    extension="${filename##*.}"  
    ext_lower=$(echo "${extension,,}")    
    g="${1%.*}"

    
    if [[ "$ext_lower" = "heic" ]];then
        heif-convert -f "$2" "$filename" "$g.$2" 
    else
        convert "$filename" "$g.$2" 
    fi
fi

# for an entire filetype. Usage:  
# convert_images heic png
# convert_images pdf jpg
# etc

for f in *.$1; do 
    echo "Converting $f to $2 format"
    filename=$(basename -- "$f")
    extension="${filename##*.}"  
    ext_lower=$(echo "${extension,,}")    
    g="${f%.*}"
    if [[ "$ext_lower" = "heic" ]];then
        heif-convert -f "$2" "$filename" "$g.$2" 
    else
        convert "$filename" "$g.$2" 
    fi
done