function imgfn2exif () (
    #set -x
    FLAG_DRYRUN=1
    FLAG_OVERWRITE=0

    function _print_help() {
        echo "Use filename to get DateTime from image and add as DateTimeOriginal Exif information"
    	echo ""
        echo "Usage: imgfn2exif <options> <file-selection>"
        echo "    <file-selection> : for example *.JPG"
        echo "    <options>        : The following options are available:"
        echo "                     : -d     write exif information"
        echo "                     : -o     overwrite existing exif information"
    }
    
    function _img_fn_2_exif () {
        file=$1
        file_name=$(basename ${file})
        file_name_prefix=${file_name%.*}
    
        if [ $FLAG_DRYRUN -eq 1 ]; then
            cmd=(echo)
        else
            cmd=()
        fi 
        cmd+=(exiftool -overwrite_original -DateTimeOriginal=${file_name_prefix} ${file})
        if [ $FLAG_OVERWRITE -eq 0 ]; then
            current_exif=$(exiftool -DateTimeOriginal ${file})
            if [ ! -z $current_exif ]; then
                echo "Exif DateTimeOriginal already exists for ${file}: ${current_exif#*: }"
                return
            fi  
        fi
    
        echo Executing: ${cmd}
        "${cmd[@]}"
    }

    while true; do
        case $1 in
            -d) 
                FLAG_DRYRUN=0
                shift;
                ;;
            -o)
                FLAG_OVERWRITE=1
                shift;
                ;;
            *)
                break
                ;;
        esac
    done

    for f in $@; do
        _img_fn_2_exif $f
    done
)